Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PHARMACEUTICAL COMPOSITION FOR THE TREATMENT OF
PARKINSON'S DISEASE
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a method and a pharmaceutical
composition for treating the symptoms associated to a neurodegenerative
disease
such as Parkinson's disease. The method and the pharmaceutical composition use
a
combination of a therapeutically effective amount of at least one of DHEA or
DHEA-S in combination with a therapeutically effective amount of a dopamine
precursor. The present invention also related to the use of at least one of
DHEA or
DHEA-S in combination with a therapeutically effective amount of a dopamine
precursor for treating a neurodegenerative disease or to manufacture a
medicament.
(b) Description of Prior Art
Parkinson's disease is attributable to a loss of dopamine in the brain caused
by dopamine-producing nerve cells of the substantia nigra that begin to
decrease in
number and to the chemical break down of the remaining dopamine in the
synapses.
The deficient level of dopamine in Parkinson's patients throws off the normal
dopamine/acetylcholine balance, since the level of acetylcholine remains
normal.
The dopamine/acetylcholine imbalance results in a lack of coordination of
movements, tremors, stiff muscles and joints, and/or difficulty moving.
Unfortunately, no cure for Parkinson's disease is known thus far despite
many attempts to stop the loss of dopamine-producing nerve cells or to restore
those
lost in the course of the disease. The only effective treatments available to
Parkinson's patients are palliative therapies, which consist in helping
patients to
manage their slow decline by replacing or simulating the effect of the
dopamine to
compensate for the dopamine deficiency, slow down or reduce the ongoing loss
of
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dopamine, or balance the level of acetylcholine with the level of dopamine in
the
brain.
Among the existing therapies for Parkinson's disease symptoms,
levodopa, (L-3,4-dihydroxyphenylalanine) is one of the most effective
medication
for controlling the stiffness, tremors, spasms, and poor muscle control of
Parkinson's. disease patients. Levodopa is a dopamine precursor which is
transported to the brain, picked up by the nerve cells that produce dopamine,
converted into dopamine and further used as a neurotransmitter. Use of
levodopa for
dopamine replacement therapy can however constitute an effective mean to
control
the symptoms of Parkinson's disease for a limited period. Indeed, as the loss
of
dopamine-producing nerve cells continues, symptoms continue to worsen and
consequently, the dose of levodopa administered to patients has to be
increased.
Over time, continual increases in the levodopa dose may eventually lead to the
development of side effects which in many cases are so important that it
becomes
impossible to increase the dose of levodopa any higher.
To avoid levodopa-associated peripheral side effects, prior art reports the
combination of that dopamine precursor with different compounds. For example,
addition of carbidopa to levodopa (Sinemet~) delays the conversion of levodopa
into
dopamine until it reaches the brain, contributes to reduce the amount of
levodopa
needs and therefore preventing or diminishing some of the side effects that
often
accompany levodopa therapy. Combination of levodopa to benserazide (Prolopa~)
prevents the conversion of levodopa into dopamine in the body, with the
exception
of brain, and therefore prevents side effects such as nausea and palpitations.
However, these combined drugs are less likely effective to prevent motor
complications such as wearing-off, on-off and dyskinesia, which are major
drawbacks associated to dopamine-replacement therapies. In addition, these
drug
combinations are ineffective to prevent levodopa response fluctuations and the
shortening of the effect of levodopa through the years of treatment.
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One of the avenue envisioned in the recent years for the treatment of in
neurodegenerative diseases such as Alzheimer and Parkinson (M. Cyr et al.,
(2000),
Curr. Pharnz. Des. 6, 1287-312) relates to the use of sex steroids. Indeed,
estrogens
and androgens (sex steroids) exert profound effects on brain differentiation,
neural
plasticity and central neurotransmission during development (M. Kawata,
(1995),
Neurosci. Res. 24, 1-46; B.S. McEwen and S.E. Alves, (1999), Endocr. Rev. 20,
279-307). In adult men and women, accumulating evidence supports a modulatory
role of these steroids in the brain (B.B. Sherwin, (1997), Neurology 48, S21-
6) and
their prime importance in the normal maintenance of brain function during
aging
(J. W. Simpkins et al., ( 1994), Neurobiol. Aging 15, S 195-7).
The role of sex steroids in Parkinson's disease is also illustrated by a
greater prevalence and incidence of Parkinson's disease in men than in women
(M.
Baldereschi et al., (2000). Neurology 55, 1358-63; G.F. Wooten et al., (2004)
J.
Neurol. Neurosurg. Psychiatry 75, 637-639). Gender differences on evolution of
symptoms and responses to levodopa treatment are also reported (K.E. Lyons et
al.,
(1998). Clin. Neuropharmacol. 21, 118-21). Modulation of dopaminergic action
pathway by estrogens is now well established. Symptoms of Parkinson's disease
and levodopa-induced dyskinesias were also shown to be modulated by estrogens
(T. Di Paolo, ( 1994). Rev. Neurosci. 5, 27-41 ).
Dehydroepiandrosterone (DHEA) and its sulfate derivative (DHEA-S) are
sex steroid precursors of both estradiol and testosterone. These steroid
precursors
are also considered as being neurosteroids, since they have been shown to be
synthesized in the brain (LH. Zwain and S.S.C. Yen, (1999). Endocrinology 140,
880-887). Studies undergone to determine a role of DHEA and DHEA-S in
Parkinson's disease suggested few time ago no particular function of these sex
steroid precursors in Parkinson's disease, since no significant difference in
cerebrospinal fluid DHEA and DHEA-S were found between Parkinson's disease
patients and age-matched controls (T. Azuma et al., (1993). J. Neurol. Sci.
120, 87-
92).
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More recent evidences however report a role pf DHEA in Parkinson's
disease. For example, international patent application published under number
WO
01/55692 disclose methods and kits whereby the onset of neuropathology, such
as
Parkinson's disease, is detected by changes in the normal levels of
neurosteroids, and
particularly DHEA and its metabolic precursors, in the brain and serum.
Modulation
of dopaminergic activity by DHEA was also shown, but to a lower extent than
estrogens. Moreover, DHEA was shown to have a protective role, protecting
animals against a dopamine depletion caused by 1-methyl-4-phenyl-1,2,3,6-
tetrahydropyridine (MPTP) (M. D'Astous et al., (2003). Synapse 47, 10-14).
Published US patent application 2002/0182196 discloses a nutritional
supplement composition for normalizing impaired or deteriorating neurological
function in humans, such as those occurring in Parkinson's disease. This
composition comprises at least one agent for normalizing or maintaining normal
neurotransmitter function in the body, at least one agent for down-regulating
cortisol
action and several others components. Particularly, this composition may
comprise
DHEA for which action is limited to cortisol action modulation.
International patent application published under number WO 99/43329
discloses a composition for treatment of a human body comprises a combination
of
at least one hormone, at least one amino acid, at least one enzyme and/or
vitamin,
and at least one mineral. The hormone of the composition comprises DHEA and
can be used in the treatment of the symptoms associated to Parkinson's
disease.
Although DHEA and DHEA-S now seem to play a role in Parkinson's
disease, many important side effects are associated to the administration of
high
doses of DHEA or DHEA-S. For example, acne, increased scalp itching, menstrual
irregularities, irritability, restlessness, heart palpitations and scalp hair
loss are
associated with a DHEA increase in the body. Therefore, it is unlikely that
Parkinson's disease therapies relying only on DHEA administration would be
successful. Therefore, it would be highly desirable to be provided with a
method
that conjugates the effect of both DHEA and levodopa.
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SUMMARY OF THE INVENTION
The present invention relates to a method for treating the symptoms
associated to a neurodegenerative disease in a patient. The method of the
present
invention comprises concomitantly administering to the patient a
therapeutically
effective amount of at least one of dehydroepiandrosterone and
dehydroepiandrosterone-sulfate with a therapeutically effective amount of a
dopamine precursor.
The present invention also relates to a pharmaceutical composition for
treating of the symptoms associated to a neurodegenerative disease and to a
composition for use in the treatment of symptoms associated to a
neurodegenerative
disease. Compositions comprise a therapeutically effective amount of at least
one of
dehydroepiandrosterone and dehydroepiandrosterone-sulfate with a
therapeutically
effective amount of a dopamine precursor.
The present invention further relates to the use of a composition in the
manufacture of a medicament for the treatment of symptoms associated to a
neurodegenerative disease, where the composition comprises a therapeutically
effective amount of at least one of dehydroepiandrosterone and
dehydroepiandrosterone-sulfate with a therapeutically effective amount of a
dopamine precursor.
The present invention finally relates to the use of a composition for the
treatment of symptoms associated to a neurodegenerative disease, where the
composition comprises a therapeutically effective amount of at least one of
dehydroepiandrosterone and dehydroepiandrosterone-sulfate with a
therapeutically
effective amount of a dopamine precursor.
For the purpose of the present invention the following terms are defined
below.
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The term "MPTP" is intended to mean 1-methyl-4-phenyl-1,2,3,6-
tetrahydropyridine.
The term "levodopa" is intended to mean L-(-)-2-amino-3-(3,4-
dyhydrophenyl)propionic acid, L-3,4-dihydrophenylalanine,3,4-dihydroxyphenyl-L-
alanine, (-)-3-(3,4-dihydroxyphenyl)-L-alanine or 3-hydroxy-L-thyrosine.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates the effect of DHEA on contralateral circling in
hemiparkinsonian MPTP-monkeys behavior by comparison to saline.
Figure 2 illustrates the effect of DHEA, alone o in combination with a
threshold dose of levodopa on Parkinsonian score in bilaterally-lesioned
parkinsonian MPTP-monkeys, by comparison to levodopa alone or saline
treatment.
Figure 3 illustrates the effect of DHEA in combination with a threshold
dose of levodopa on contralateral circling behavior in hemiparkinsonian MPTP-
monkeys, by comparison to levodopa alone or saline treatment.
Figure 4 illustrates the effect of DHEA, alone or in combination with a
threshold dose of levodopa on the duration of the levodopa-induced effect in
bilaterally-lesioned parkinsonian MPTP-monkeys, by comparison to levodopa
alone
or saline treatment.
Figure 5 illustrates the effect of optimal DHEA dose in combination with
a threshold levodopa dose on ipsilateral and contralateral circling in
hemiparkinsonian MPTP-monkeys, by comparison to levodopa alone or saline
treatment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides a method for treating the symptoms
associated to a neurodegenerative disease. The neurodegenerative disease of
the
present invention is any of disease, disorder, condition, sickness or illness
that
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causes any degeneration, lesion, damage, deterioration or collapsing of
neurons,
preferably neurons of the substantia nigra and more preferably dopamine-
producing
neurons of the substantia nigra. The neurodegenerative disease includes any of
Alzheimer's Disease (AD), Lewy body variant Alzheimer's Disease, amyotrophic
lateral sclerosis, dementia, multiple system atrophy, neuronal intranuclear
inclusion
disease, Parkinson's disease, prion related diseases, tauopathies, tri-
nucleotide repeat
diseases and Tourettes syndrome. The disease is however preferably Parkinson's
disease.
By treating the symptoms of the neurodegenerative disease, it is intended
to mean any way for alleviating, relieving, curing, healing, reducing or
improving
the symptoms associated to the neurodegenerative disease, and should not be
restricted to total or complete disappearance of the symptoms. For the purpose
of
the present invention, symptoms are those generally associated to
neurodegenerative
diseases and include tremors, muscle stiffness, joint stiffness, spasm, low
muscle
control, movement difficulty, ipsilateral circling, rigidity in arms, rigidity
in legs,
reduced locomotor activity, movement coordination or a combination of these
symptoms. For example, the method and the pharmaceutical composition of the
present invention showed that DHEA significantly improves the levodopa-induced
locomotor activity and contralateral circling. DHEA improvement of levodopa-
induced treatments of neurodegenerative diseases' symptoms may occur by any
DHEA action pathway known in the prior art. For example, levodopa-induced
locomotor activity or contralateral circling in MPTP-monkeys may occur through
the binding of DHEA to an allosteric site on GABAa receptors, DHEA-S being
known in the art to behave as a negative modulator of the GABAa receptor
complex
(M.D. Majewska et al., (1990). Brain Res. 526, 143-146.). DHEA being a
precursor
of 17(3-estradiol, DHEA and DHEA-S may potentiate levodopa-induced activity by
acting as an estrogenous pro-drug, since enzymes responsible for the
transformation
of DHEA into 17~i-estradiol are expressed in the brain (LH. Zwain and S.S.C.
Yen,
(1999). Endocrinology 140, 880-887).
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The dopamine precursor of the present invention is administered
concomitantly to DHEA or DHEA-S. By concomitant administration, it is intended
any form of administration that enables the potentiation of dopamine precursor-
induced treatment of the symptoms associated to a neurodegenerative condition.
Such concomitant administration include any form of administration in which
DHEA, DHEA-S and/or dopamine precursors are administered together, such as in
association in a pharmaceutical composition, or separately. A separate
administration of DHEA, DHEA-S and dopamine precursor is preferably performed
within a time frame that enables each of these compounds or a combination of
these
compounds to enter into blood circulation, go by the hematoencephalic barrier
and
exert its action into the brain, where the action of one compound potentiates
the
action of another one. The concomitant administration of least one of
dehydroepiandrosterone and dehydroepiandrosterone-sulfate with a
therapeutically
effective amount of a dopamine precursor may be performed by any
administration
route known in the prior art and includes, but is not limited to rectal,
buccal,
sublingual, intravenous, subcutaneous, intradermal, transdermal,
intraperitoneal,
oral, parenteral and topical administration.
Oral administration includes gavage, nasogastric gavage and any
administration mode that makes use of a solid or liquid pharmaceutical
composition
comprising at least one of DHEA, DHEA-S and dopamine precursor and suitable
for
oral administration. The pharmaceutical composition suitable for oral
administration may be presented as discrete units such as capsules, cachets,
caplets
or tablets, each containing a predetermined amount of at least one of DHEA,
DHEA-S and dopamine precursor, as a powder or granules or as a solution or
suspension in an aqueous liquid, a non-aqueous liquid, an oil-in-water
emulsion or a
water-in-oil emulsion. Such compositions may be prepared by any of the methods
of pharmacy, including the step of bringing the DHEA, DHEA-S, dopamine
precursor or combination thereof into association with the carrier which
includes
one or more necessary ingredients. In general, the compositions are prepared
by
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uniformly and intimately admixing the DHEA, DHEA-S or dopamine precursor
with liquid carriers or finely divided solid carriers or both, and then, if
necessary,
shaping the product into the desired presentation. For example, a tablet may
be
prepared by compression or moulding, optionally with one or more accessory
ingredients. Compressed tablets may be prepared by compressing, in a suitable
machine, the active ingredient in a free-flowing form such as powder or
granules,
optionally mixed with a binder, lubricant, inert diluent, surface active or
dispersing
agent. Moulded tablets may be made by moulding, in a suitable machine, a
mixture
of the DHEA, DHEA-S or dopamine precursor moistened with an inert liquid
diluent.
The mode of administration by injection includes continuous infusion as
well as single or multiple boluses. Useful administration types or modes also
include the use of pumps, such as implantable internal pumps, for continuous
infusion into a blood vessel or at different sites such as the peritoneal
cavity or
subcutaneously, as disclosed in the art. The DHEA, DHEA-S, dopamine precursor
or combination thereof can be formulated as a sterile pharmaceutical
composition
for therapeutic use which is suitable for intravenous or intraarterial
administration.
The product may be in a solvent-free form and ready to be reconstituted for
use by
the addition of a suitable carrier or diluent, or alternatively, it may be in
the form of
an aqueous or organic solution. For reconstitution of a solvent-free product
in
accordance with the present invention, one may employ a sterile diluent, which
may
contain materials generally recognized for approximating physiological
conditions.
In this manner, the sterile diluent may contain salts and/or buffering agents
to
achieve a physiologically acceptable tonicity and pH, such as sodium chloride,
phosphate and/or other substances which are physiologically acceptable and/or
safe
for use.
When used as an aqueous solution, the pharmaceutical composition will
for the most part contain many of the same substances described above for the
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reconstitution of solvent-free product. When used in solution in an organic
solvent,
a small volume of the solution containing the DHEA, DHEA-S, dopamine precursor
or combination thereof will be diluted with an aqueous solution that will
contain
many of the same substances described above for the reconstitution of a
solvent-free
product. The pharmaceutical composition, for the most part, will thus contain
many
of the same substances described above for the reconstitution of a solvent-
free
product. Pharmaceutical composition, method and uses that are the object of
the
present invention may make use of sterile solutions for injection,
encapsulated in
liposomes or embedded, for example in suppositories, for slower long-lasting
release. Suitable vehicles and their formulations, including human proteins,
such as
human serum albumin, are described for instance in the background art.
Transdermal administration includes administration by means of a patch,
cream, ointment, balm, unguent, emulsion, lotion or lotion that comprises at
least
one of DHEA, DHEA-S and dopamine precursor.
The dopamine precursor used for the purpose of the present invention is
preferably levodopa, also commonly known as, L-3,4dihydrophenylalanine, L-dopa
or T.L-dopa or any derivative thereof. Such levodopa derivative includes
levodopa
methyl ester (LDME) (U.S. Pat. No. 4,826,875) or L-meta-tyrosine (U.S. Pat.
No.
3,838,008), levodopa ethyl ester (LDEE)(U.S. Pat. No. 6,696,600) or salt
thereof.
Levodopa derivative salt includes, but is not limited to fumarate salt,
fumarate
dehydrate salt, hydrochloride salt, the hydrobromide salt, the nitrate salt,
perchlorate
salt, phosphate salt, sulfate salt, formate salt, acetate salt, aconite salt,
ascorbate salt,
benzosulphonate salt, benzoate salt, cinnamate salt, citrate salt, embonate
salt,
enantate salt, fumarate salt, glutamate salt, glycolate salt, lactate salt,
maleate salt,
malonate salt, mandelate salt, methane sulphonate salt, myristate salt,
octanoate salt,
phthalate salt, salicylate salt, sorbate salt, stearate salt, succinate salt,
succinate
dehydrate salt, tartrate salt and the like. Such salts may be obtained
following
procedures known in the art.
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Dopamine precursor, alone or in combination with DHEA, DHEA-S or a
combination thereof, can be administered concurrently to at least one of a
carrier and
a therapeutic agent. Therapeutic agent includes, but is not limited to,
exogenous
dopamine, agents that will be metabolized into the organism so as to provide
dopamine to the brain, such as dopamine precursors, dopamine agonist,
therapeutic
agents that enhance the release of dopamine stored by the dopamine-producing
neurons, therapeutic agents that contribute to adjust acetylcholine level to
provide a
suitable dopamine/acetylcholine balance, catechol-O-methyl transferases
(COMT),
monoamine oxidase B inhibitors, monoamine reuptake inhibitors, Dopamine
decarboxylase inhibitors, dopamine activity enhancers or a combination
thereof.
Examples of such agents known in the art include bromocriptine, bromocriptine
mesylate (Parlodel~), pergolide, pergolide mesylate (Permax~), amantadine
hydrochloride (Symmetrel~), trihexyphenidyl HCI (Artane ), benztropine
mesylate
(Cogentin~), pramipexole (MirapeX ), ropinirole hydrochloride (Requip~),
tolcapone, cabergoline, apomorphine, domperidone, entacapone selegiline,
carbidopa (Sinement~), benserazide (Prolopa ), (Bupropiori ), Nomifensine~ or
the
like.
The carrier to which is combined DHEA or DHEA-S and dopamine
precursor or a combination thereof is a pharmaceutically acceptable carrier.
In
practical use, these compounds can be combined as active ingredients in
intimate
admixture with a pharmaceutical carrier according to conventional
pharmaceutical
compounding techniques. The carrier may take a wide variety of forms depending
on the form desired for administration. In preparing the compositions for oral
dosage form, any of the usual pharmaceutical media may be employed, such as,
water, glycols, oils, alcohols, flavouring agents, preservatives, coloring
agents and
the like in the case of oral liquid preparations (for example, suspensions,
elixirs, and
solutions), or carriers such as starches, sugars, microcrystalline celluloses,
diluents,
granulating agents, lubricants, binders, disintegrating agents and the like in
the case
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of oral solid preparations ( for example, powders, capsules, and tablets). If
desired,
tablets may be coated by standard aqueous or non aqueous techniques.
In addition to the herein-above described carrier, additional
pharmaceutical methods may be employed to control the duration of the action
of
DHEA or DHEA-S and dopamine precursor or combination thereof. For example,
controlled-release preparations may be achieved through the use of
macromolecules
forming complexes with or absorbing the DHEA or DHEA-S and dopamine
precursor or combination thereof. The controlled delivery may be achieved by
selecting appropriate macromolecules, for example, polyesters, polyamino
acids,
polyvinyl pyrrolidone, ethylene-vinyl acetate, methyl cellulose, carboxymethyl
cellulose, protamine sulfate or serum albumin, the appropriate concentration
of
macromolecules, as well as the methods of incorporations. In this manner,
release
of DHEA or DHEA-S and dopamine precursor or combination thereof can be
controlled. Another possible method useful in controlling the duration of
action by
controlled release preparations is the incorporation of DHEA or DHEA-S and
dopamine precursor or combination thereof into particles of a polymeric
material
such as polyesters, polyamino acids, hydrogels, poly(lactic acid), or ethylene-
vinyl
acetate copolymers. Instead of incorporating the DHEA or DHEA-S and dopamine
precursor or combination thereof into polymeric particles, it is also possible
to
entrap it in microcapsules prepared, for instance, by coacervation techniques
or by
interfacial polymerization (for example hydroxymethyl cellulose or gelatine
microcapsules and polymethyl methacrylate microcapsules, respectively), in
colloidal drug delivery systems (for example, liposomes, albumin microspheres,
microemulsion, nanoparticles and nanocapsules) or in macroemulsions. Such
techniques are well known in the art.
The patient of the present invention is an animal, and preferably a
mammal, and more preferably a murine, a feline, a canine, a monkey or a human.
However, any animal that may benefit from the concomitant administration of a
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therapeutically effective amount of at least one of dehydroepiandrosterone and
dehydroepiandrosterone-sulfate with a therapeutically effective amount of a
dopamine precursor is part of the invention.
The present invention will be more readily understood by referring to the
following examples which are given to illustrate the invention rather than to
limit its
scope.
Example 1
POTENTIALISATION OF LEVODOPA ACTIVITY BY DHEA
ADMINISTRATION TO MPTP-MONKEYS
MATERIALS AND METHODS
Six hemiparkinsonian ovariectomized female macaca fasicularis monkeys
weighing 2.8-6.5 kg were used in this experiment. During induction of the
parkinsonian syndrome, they received 1-methyl-4-phenyl-1,2,3,6-
tetrahydropyridine
(MPTP, 3mg) via an Alzet pump during a period of 1-2 weeks according to the
monkey. The procedure consisted of putting the pump in the left substantia
nigra and
the MPTP infused lesioned the dopaminergic cells. The animals were used at
least 5
months after the induction of their hemiparkinsonian state at which time they
had
stabilized. For a further experimentation, 6 bilaterally-lesioned parkinsonian
macaca
fasicularis monkeys were used. The induction of the parkinsonian syndrome was
performed according to the above-described methodology, except that the Alzet
pump was installed so as to lesion dopaminergic cells of the substantia nigra
in both
brain hemispheres.
To determine the effect of levodopa, DHEA or combination thereof on
parkinsonian monkeys, ipsilateral and contralateral circling was monitored in
hemiparkinsonian monkeys while Parkinsonian score was determined in
bilaterally-
lesion parkinsonian monkeys. Hemiparkinsonian monkeys turn towards the
ipsilateral side of the lesion (to the left) under basal conditions and upon
dopaminergic stimulation this circling changes for the contralateral side (to
the
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right). Parkinsonian score was determined in bilaterally-lesion parkinsonian
monkeys according to the method known in the art. All received the same
treatments and were their own controls. Monkeys were first treated with
levodopa
for priming until a stable antiparkinsonian behavior was observed. During the
investigation of DHEA administered alone, priming of the monkeys was continued
with administration of levodopa/benserazide (50/l2.Smg) given twice weekly.
DHEA treatments were started on the third day after the last levodopa dose.
When
treatments involved a combination of levodopa with DHEA, the monkeys did not
receive additional levodopa priming.
DHEA was administered at different doses (1, 5, and 15 mglkg) by
nasogastric gavage (n.g.) alone and in combination (DHEA: 1, 5, 10 and 15
mg/kg
n.g.) with a s.c. T.L-Dopa. Threshold doses of levodopa, that is the minimal
dose to
obtain contralateral circling were sought for each of the MPTP-monkeys and
varied
from one monkey to another from 3 to 8 mg/kg (3, 4, 4.5, 5, 5, and 8 mg/kg).
Higher doses of DHEA (25-100mg/kg) alone or with T.L-Dopa were also tested in
a
similar paradigm.
Treatments were administered in the morning and each animal was
recorded via a video camera system. Duration of locomotor activation lasted
for 90
min for all hemiparkinsonian animals and treatments. Hence, behavior was
measured for 90 min with left and right circling quantified for 30-minute
periods.
Each treatment was repeated 2-3 times and averaged for each monkey. Saline and
T.L-Dopa treatments were performed in the beginning and the end of each
different
hormonal treatment and found not significantly different. Hence, these values
were
grouped.
Experimental data was compared using an ANOVA for repeated measures
followed by post-hoc pair wise comparisons with Fisher's probability of least
significant difference test (PLSD). A p<0.05 was required for the results to
be
considered statistically significant. Statistical comparison of square root
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transformation of the data was used to stabilize variance when required (D.C.
Montgomery ( 1991 ) Third Edition, Design and analysis of experiments. ed.
Whileys
and Sons pp. 216).
RESULTS
The hemiparkinsonian and bilaterally-lesion parkinsonian MPTP-
monkeys under basal conditions or after saline treatment displayed ipsilateral
circling behavior (hemiparkinsonian monkeys) or parkinsonian symptoms
(bilaterally-lesion parkinsonian monkeys). After dopaminergic stimulation with
DHEA alone, DHEA combined to T.L-Dopa, they decreased their ipsilateral
circling
and started turning to the contralateral side relative to the lesion or the
parkinsonian
symptoms were reduced.
DHEA alone investigated at different doses was able to induce
contralateral circling and reduce the Parkinsonian score, as shown in Figure 1
and
Figure 2. Thus, 1-15 mg/kg of DHEA significantly and similarly increased
contralateral circling (mean/30 min) compared to saline treatment. Duration of
the
DHEA effect lasted for 90 min. The effect of DHEA at different doses with a
T.L-
Dopa is shown in Figure 2 and Figure 3. The smallest dose of dose of DHEA
(lmg/kg) added to T.L-Dopa significantly increased contralateral circling
(mean/30min) and decreased the Parkinsonian score compared to saline or T.L-
Dopa
treatment alone. T.L-Dopa combined with higher doses of DHEA (5, 10 and 15
mg/kg) significantly increased the contralateral circling (mean/30min) and
reduced
the Parkinsonian score compared to saline treatment. Higher doses of DHEA (25-
100mg/kg) alone or in combination with T.L-Dopa gave similar results. DHEA
treatment ( 1 and 5 mg/kg) also changed the duration of levodopa effect, which
was
increased from approximately 40% at both DHEA concentrations (Figure 4).
DHEA alone or combined with levodopa did not produce a significant
dose-response on circling behavior. A maximal response was obtained with
different doses in the monkeys tested for DHEA alone or combined with
levodopa.
CA 02469152 2004-05-28
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Hence, in Figure 5 is shown the mean of the optimal dose of DHEA for each
monkey for ipsilateral, contralateral and their difference (ipsilateral-
contralateral).
Levodopa increased contralateral and decreased ipsilateral circling thus
reducing the
overall ipsilateral-contralateral circling. The optimal dose of DHEA combined
with
DHEA significantly potentiated this effect. A maximal response was observed
with
1 or Smg/kg of DHEA combined with levodopa depending on the monkey. No
correlation was found between the dose for the maximal response and baseline
circling or threshold dose of levodopa.
In conclusion, DHEA potentiates levodopa-induced locomotor activity in
a MPTP-monkey model of Parkinson's disease. The effective doses of DHEA are in
the range used safely in humans. The present paradigm used minimal threshold
doses of levodopa. Hence, adding DHEA to levodopa therapy could enable the
reduction of the dose of levodopa and hence protect against the side effects
associated with this drugs, which are dose-related. Finally, DHEA contributes
to
prolong the effects of levodopa.
While the invention has been described in connection with specific
embodiments thereof, it will be understood that it is capable of further
modifications
and this application is intended to cover any variations, uses, or adaptations
of the
invention, following, in general, the principles of the invention, and
including, such
departures from the present disclosure as come within known or customary
practice
within the art to which the invention pertains and as may be applied to the
essential
features hereinbefore set forth, and as follows in the scope of the appended
claims.
