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PubMed1999

Effect of reserpine on behavioural responses to agonists at 5-HT1A, 5-HT1B, 5-HT2A, and 5-HT2C receptor subtypes.

Rats were given a single dose of reserpine (5 mg/kg s.c.) and behavioural responses to agonists at 5-HT receptor subtypes compared with those of control animals 21 days later. The following effects of activating postsynaptic 5-HT1A receptors by the agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) were significantly increased: tail-flick, reciprocal forepaw treading, flat body posture. The hyperphagic effect of activating presynaptic 5-HT1A receptors by 8-OH-DPAT tended to increase and hypothermia on activating postsynaptic 5-HT1A sites tended to decrease. The hyperlocomotor effect of activating 5-HT1A sites also tended to decrease possibly as a result of a dependence of this response on the known depletion of catecholamines by reserpine. Head shakes on activating 5-HT2A receptors by 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) and two effects of activating 5-HT2C receptors by 1-(3-chlorophenyl) piperazine (mCPP) were significantly increased (hypophagia, anxiety) and a third effect, hypolocomotion tended to increase but hypophagia on activating postsynaptic 5-HT1B receptors by CP-94, 253 was significantly attenuated. The results are discussed with particular reference to altered 5-HT function in depression.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2000

Reserpine or chronic paroxetine treatments do not modify the vesicular monoamine transporter 2 expression in serotonin-containing regions of the rat brain.

To date, very little information is available about the regulation of vesicular monoamine transporter in central serotonergic regions. The expression of the vesicular monoamine transporter 2 (VMAT2) has been studied in the serotonergic system of the rat brain after an 18 day treatment with the serotonin selective-reuptake inhibitor paroxetine (10 mg/kg, i.p., once daily). This treatment, while increasing serotonergic transmission, did not modify either VMAT2 mRNA expression or (3)H-dihydrotetrabenazine binding site density in any of the studied regions. These results suggest that VMAT2 regulation in the central serotonergic system is not involved in the mechanism of action of antidepressants. In addition, a single administration of reserpine (5 mg/kg, s.c.), while blocking the vesicular monoamine uptake function, had no effect on VMAT2 immunoreactivity in the dorsal raphe nucleus 2 or 30 days after injection. It is concluded that neither a reduction (reserpine) nor an enhancement (paroxetine) of the serotonin transmission induces VMAT2 regulation in serotonergic system in the rat brain.

Animals↗
PubMed1988

Age-related changes in the recovery of noradrenaline content in sympathetic fibres after reserpine treatment.

The aim of the present study was to evaluate noradrenaline recovery times in sympathetic fibres after reserpine administration by using fluorescence histochemical techniques. The spleen, the kidney, and the large intestine were examined 24 h to 15 d after reserpine treatment, in both young and aged male Sprague-Dawley rats, in order to establish not only the possible differences in recovery times of the various organs, but also if senescence can influence these times. The complete restoration of the noradrenaline content took place sooner in younger rats than in aged ones, and, within the same age-group, the recovery was quicker in the spleen and needed longer times in the large intestine, particularly in aged rats.

Aging↗
PubMed1997

Effects of dopaminergic agents on reversal of reserpine-induced impairment in conditioned avoidance response in rats.

Male Slc:Wistar, Std:Wistar, and Slc:F344/N rats had good acquisition of the conditioned avoidance response (CAR), while that of the male Slc:Wistar/ST, Jcl:Wistar, and Crj:Wistar rats was bad. Reserpine-induced impairment (RII) in CAR was observed 2-72 h after administration of dopaminergic (DAergic) agents in male Slc:Wistar rats. Amitriptyline (5-80 mg/kg, P.O.), imipramine, desipramine, cis-dosulepine, and trans-dosulepine at dose of 40 mg/kg, P.O. showed no antagonism against RII in CAR 20-23 h after reserpine injection (1 mg/kg, S.C.). However, the atypical antidepressive agents sibutramine (5-10 mg/kg, P.O.), bupropion (40 mg/kg, P.O.), and nomifensine (10-40 mg/kg, P.O.) exhibited antagonism against RII in CAR. The calcium channel antagonists flunarizine, nimodipine, and KP-840 at dose of 10 and 100 mg/kg, P.O., the cerebral improving agent indeloxazine (20-80 mg/kg, P.O.), the anticholinergic agent atropine (5-40 mg/kg, P.O.), 5-hydroxy-L-tryptophan (5-HTP) (40 mg/kg, I.P.), a precursor of 5-hydroxytryptamine (5-HT), and (+/-)-threo-dihydroxyphenylserine [(+/-)-threo-DOPS] (20-200 mg/kg P.O.), a norepinephrine (NE) precursor, showed no antagonism against RII in CAR. The DAergic agents methamphetamine (5 mg/kg, P.O.) and amantadine (50-250 mg/kg, P.O.), L-DOPA (200 mg/kg, P.O.), and the DAergic D1/D2 receptor agonist apomorphine (0.1-1 mg/kg, S.C.) showed marked antagonism against RII in CAR. Although the DAergic D1-receptor agonist KF-38393 (0.3-30 mg/kg, I.P.) and the DAergic D2-receptor agonist quinpirole (0.3-10 mg/kg, I.P.) induced only a weak recovery of RII in CAR when they were administered alone, in contrast to a potent synergistic recovery of RII in CAR, which was observed when SKF-38393 (1 mg/kg, I.P.) and quinpirole (1 mg/kg, I.P.) were administered together. These results suggest that the DAergic nervous system rather than the adrenergic or 5-HT nervous system is involved in RII in CAR, and that both the DAergic D1- and D2-mediated nervous systems play important roles in this process.

Animals↗
PubMed1999

NMDA receptor antagonists inhibit apomorphine-induced climbing behavior not only in intact mice but also in reserpine-treated mice.

The present study showed that the noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonists, MK-801 {(+)-5-methyl-10,11-dihydroxy-5H-dibenzo-[a,d]-cyclohepten-5,10-im ine hydrogen maleate}, ketamine, dextrorphan and dextromethorphan attenuated apomorphine-induced climbing behavior in reserpine-treated mice. In addition, the competitive NMDA receptor antagonists, D(-)-2-amino-5-phosphonopentanoic acid (AP-5) and D(-)-3-(2-carboxypipera-zine-4-yl)-propyl-1-phosphonic acid (CPP), also inhibited the apomorphine-induced climbing behavior in reserpine-treated mice as well as in intact mice. Previous work in our laboratory had shown that the noncompetitive NMDA receptor antagonists, MK-801, ketamine, dextrorphan and dextromethorphan cause a pronounced inhibition of apomorphine-induced cage climbing behavior in intact mice, suggesting the involvement of NMDA receptors in the glutamatergic modulation of dopaminergic function at the postsynaptic dopamine (DA) receptors. Therefore, the present results strongly support our previous conclusion that the NMDA receptors play important roles in the glutamatergic modulation of dopaminergic function at the postsynaptic DA receptors.

Animals↗
PubMed1981

Comparison of behavioral changes in cats treated with intracerebroventricular 6-hydroxydopamine and reserpine.

In singly- and group-housed cats, an intraventricular injection of 6-hydroxydopamine (6-OHDA) in doses up to 1.0 mg, after a latent period of 1 to 3 days, evoked motor responses including tremor, ataxia, rigidity, weakness with adynamia and clonic-tonic convulsions. However, the intraventricular administration of 6-OHDA in a dose of 2.0 mg in group-housed cats, also after a latent period of 1 to 3 days, caused aggression, a restlessness, irritability, rage, fear, threat, attack, fighting and flight. These responses were accompanied by autonomic signs of mydriasis and dyspnoea and motor changes including tremor, ataxia, rigidity, weakness with adynamia and clinic-tonic convulsions. In the singly-housed cat only the latter motor phenomena were observed after the higher dose. Intraventricular injection of reserpine (0.5-1.0 mg) in both singly- and group-housed cats produced catalepsy, sedation, miosis, ptosis, defecation and micturition as well as motor responses of tremor, rigidity and akinesia. It is concluded that although 6-OHDA and reserpine evoke different behavioral effects, the motor changes are similar.

Affect↗
PubMed2002

In vitro activity of clinafloxacin in comparison with other quinolones against Stenotrophomonas maltophilia clinical isolates in the presence and absence of reserpine.

A total of 33 Stenotrophomonas maltophilia clinical isolates were tested for their susceptibility to clinafloxacin in comparison with ciprofloxacin, levofloxacin, moxifloxacin, nalidixic acid, norfloxacin, sparfloxacin and trovafloxacin. The MIC(50) and MIC(90) were as follows: ciprofloxacin 4 and 64 microg/mL; clinafoxacin 0.5 and 4 microg/mL; levofloxacin 2 and 32 microg/mL; moxifloxacin 1 and 8 microg/mL; nalidixic acid 8 and 128 microg/mL; norfloxacin 64 and 256 microg/mL; sparfloxacin 1 and 16 microg/mL; and trovafloxacin 1 and 8 microg/mL. Clinafloxacin was the most active quinolone, with only a 15.1% of strains showing resistance. When the MICs were determined in the presence of 25 microg/ml of reserpine, the MIC(90) of trovafloxacin and moxifloxacin did not change, whereas decreased 2-fold for clinafloxacin, levofloxacin, sparfloxacin and nalidixic acid, and 4- and 8-fold for ciprofloxacin and norfloxacin respectively. No clinafloxacin-resistant strains were observed when the MIC was performed in the presence of reserpine. Therefore, clinafloxacin shows the better "in vitro"activity against these 33 strains of S.maltophilia.

Anti-Infective Agents↗
PubMed1993

Ultrastructural morphometric investigation of the heart of rabbits after a single administration of reserpine.

The ultrastructure of myocardial cells of chinchilla rabbits was morphometrically examined after administration of one dose of reserpine. The results show that 24 hours after administration of reserpine, there is a decrease in the number and an increase in the size of the mitochondria, a relaxation or narrowing and ramification of myofibrils, an increase in intracellular lipid content compared with control animals. These changes are the result of functional and chemical desympathization and they represent an ultrastructural-morphometric characteristic of the action on cardiomyocytes.

Animals↗
PubMed1979

The effects of atropine and reserpine on cortical kindling in the rat.

The effects on cortical kindling of atropine (a muscarinic, cholinergic blocking agent) and reserpine (a depleter of catecholamines and 5 hydroxytryptamine) were tested in this study. Atropine, which had previously been found to retard amygdaloid kindling, had similar but somewhat weaker effects on cortical kindling. Reserpine also had similar effects on cortical kindling compared to subcortical kindling in that it potentiated seizure responses.

Animals↗
PubMed1979

Structure--activity relationships of n-substituted dopamine and 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene analogues: behavioral effects in lesioned and reserpinized mice.

N,N-Disubstituted dopamine and 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (6,7-ADTN) analogues were synthesized and tested intraperitoneally in mice for dopamine agonism. Compounds inducing asymmetric postures in unilaterally caudectomized mice were further tested in mice treated with reserpine and alpha-methyl-p-tyrosine methyl ester. ED50 values determined for reversal of reserpine-induced catalepsy were used to rank drug potency and correlated with molecular structure. N-n-Propyl N-substituted compounds were more effective than other N,N-dialkyl homologues. Of these, analogues with one alkyl group larger than propyl became inactive or their dopaminomimetic effect was reduced when the propyl was replaced with a larger group. N-Monosubstituted analogues were inactive as dopamine agonists. N-n-P-r-N-n-Bu-6,7-ADTN was six times more potent than N-n-propyl-N-n-pentyl- and N-n-propyl-N-phenethyldopamine but ten times less potent than apomorphine. The availability of an array of structurally related dopamine analogues with dopaminomimetic properties may make it possible to test the hypothesis that there are more than one type of dopamine receptor and that stereotypy and locomotor activity may have different central nervous system loci. Moreover, they may be of potential use in the treatment of parkinsonism and other extrapyramidal disorders.

Animals↗
PubMed2003

Preparation of perhydroisoquinolines via the intramolecular Diels-Alder reaction of N-3,5-hexadienoyl ethyl acrylimidates: a formal synthesis of (+/-)-reserpine.

The intramolecular Diels-Alder reaction of N-3,5-hexadienoyl ethyl acrylimidates provides an efficient method for the synthesis of cis-fused hexahydroisoquinolones. As a demonstration of the stereochemical control offered by this cycloaddition, two approaches to the construction of the DE rings of reserpine are reported. In the second entry, N-((4-(trimethylsilyl)ethoxymethoxy)methyl-6-benzyloxy-3Z,5E-hexadienoyl)-1-aza-2-ethoxy-1,3-butadiene (40) undergoes cycloaddition to produce as the major product (4aS,7R,8aS)-7-benzyloxy-5-((2-trimethylsilyl)ethoxymethoxy)methyl-3,4,4a,7,8,8a-hexahydroisoquinol-3-one (41). Cycloadduct 41 is then stereospecifically elaborated to (4aS,5S,6R,7R,8aR)-6-methoxy-5-methoxycarbonyl-7-(3,4,5-trimethoxy)benzoyldecahydroisoquinoline-2-carboxylic acid methyl ester (3), a key intermediate previously transformed to reserpine.

Combinatorial Chemistry Techniques↗
PubMed1998

Effect of tetramethylpyrazine on reserpine-induced gastric lesion in rats.

The present study was undertaken to determine the effect of tetramethylpyrazine administered intraperitoneally on gastric lesions, gastric acid secretion, gastric barrier mucus secretion, and gastric contraction in reserpine-treated rats. The results of this study demonstrated that tetramethylpyrazine at doses of 0.5, 1, 10, and 20 mg/kg significantly inhibited the formation of gastric lesions induced by reserpine, with suppressive rates of 57.5%, 64.0%, 94.1%, and 96.0%, respectively. Tetramethylpyrazine (1 and 20 mg/kg) significantly prompted the secretion of gastric barrier mucus but had no effect on the secretion of gastric acid. Our findings also showed that tetramethylpyrazine (1 and 20 mg/kg) significantly suppressed the frequency of gastric contractions, but had no effect on the amplitude of gastric contraction. These results indicate that the protection of tetramethylpyrazine results, in part, from promoting gastric barrier mucus secretion and suppressing the frequency of gastric contraction, but not from suppressing the secretion of gastric acid and the amplitude of gastric contraction.

Animals↗
PubMed1997

Serotonin synthesis increased in terminals four days after reserpine treatment: an autoradiographic study in rat brain.

The rate of 5-HT synthesis was determined in discrete rat brain regions 4 days after a single dose of reserpine (10 mg/kg) or reserpine carrier (controls), using an autoradiographic method with labelled alpha-methyl-L-tryptophan as a tracer. The results show that the rate of 5-HT synthesis was unchanged in the dorsal and median raphe, significantly decreased in the raphe magnus, and significantly increased in areas rich in serotonergic nerve terminals (i.e., hypothalamus, hippocampus, median geniculate body, parietal and visual cortices). An increase in tryptophan hydroxylase activity could account for the increase in the rate of serotonin synthesis seen in some regions. Since the 5-HT synthesis rate showed regional variability there seems to be a need for regional studies of the effect of drugs on the 5-HT synthesis. In addition, the 5-HT synthesis rate was not significantly different from that in controls in many of the brain regions.

Animals↗
PubMed2000

The group II metabotropic glutamate receptor agonist, DCG-IV, alleviates akinesia following intranigral or intraventricular administration in the reserpine-treated rat.

1. This study examined whether activation of group II metabotropic glutamate (mGlu) receptors in the substantia nigra pars reticulata (SNr) could reverse akinesia in a rodent model of Parkinson's disease (PD). 2. Male Sprague Dawley rats, stereotaxically cannulated above either the SNr or third ventricle, were rendered akinetic by injection of reserpine (5 mg kg-1 s.c.). Eighteen hours later, the rotational behaviour induced by unilateral injection of the group II mGlu receptor agonist, (2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine (DCG-IV), was examined. 3. Following intranigral injection, DCG-IV (0.125-0.75 nmol in 0.1 microliter) produced a dose-dependent increase in net contraversive rotations (n = 6-8 animals per dose), reaching a maximum of 395 +/- 51 rotations 60 min-1 after 0.75 nmol. The effects of DCG-IV (0.5 nmol) were inhibited by 63.0 +/- 9.0% following 30 min pre-treatment with the group II mGlu receptor antagonist, (2S)-alpha-ethylglutamic acid (EGLU; 100 nmol in 0.2 microliter; n = 6). 4. Following intraventricular injection, DCG-IV (0.125-1.5 nmol in 2 microliters) produced a dose-dependent increase in bilateral locomotor activity (n = 6-7 animals per dose), reaching a maximum of 180 +/- 21 locomotor units 30 min-1 after 0.5 nmol. Pre-treatment with EGLU (200 nmol in 2 microliters) inhibited the effects of DCG-IV (0.5 nmol) by 68.2 +/- 12.3% (n = 5). 5. These data show that activation of group II mGlu receptors in the SNr provides relief of akinesia in the reserpinized rat model of PD. The reversal seen following intraventricular administration supports the likely therapeutic benefit of systemically-active group II mGlu receptor agonists in PD.

Animals↗
PubMed1977

Modifications of major aspects of myocardial ribonucleic acid metabolism as a response to noradrenaline. Action of the hormone on cytoplasmic processing of ribonucleic acid after reserpine treatment.

Treatment of perfused rabbit heart with reserpine causes a decrease of incorporation of labelled precursors into RNA species of subcellular fractions and polyamines. Ornithine decarboxylase, S-adenosylmethionine decarboxylase and cytoplasmic Mn2+-stimulated polyadenylate polymerase activities are not modified. Addition of noradrenaline to reserpine-treated perfused hearts enhances, compared with the control, the incorporation of precursor into RNA in all subcellular fractions other than the nuclear one, restores incorporation of labelled putrescine into polyamines, enhances ornithine decarboxylase and S-adenosylmethionine decarboxylase activities and causes a 12-fold increase in cytoplasmic Mn2+-dependent polyadenylate polymerase activity. After treatment with noradrenaline the increase in radioactivity was found solely in AMP after hydrolysis of microsomal RNA to nucleoside monophosphates.

Adenosylmethionine Decarboxylase↗
PubMed1976

Interaction of dopamine, methyldopa and reserpine in the sympatho-adrenal system in essential hypertension.

1. The interactions of dopamine, reserpine and methyldopa on blood pressure of normal subjects and of those with essential hypertension were examined. 2. When biosynthesis of noradrenaline from dopamine was blocked by reserpine, dopamine induced a prominent depressor effect in essential hypertension. 3. The long-term treatment with methyldopa induced a marked potentiateion of the pressor action of domapine in hypertension, although no significant pressor response was found in normal subjects. 4. It is suggested that methylnoradrenaline may accumulate in peripheral nerve endings of patients with essential hypertension in comparison with normal subjects, and this accumulated methylnoradrenaline potentiates the pressor response to dopamine in essential hypertension.

Adult↗
PubMed1999

Catecholamines in pericardial fluid of normotensive, spontaneously hypertensive and reserpine-treated rats.

In this study our aims were to investigate the presence and source of catecholamines in pericardial fluid of normotensive, reserpine-treated and spontaneously hypertensive rats. We found that noradrenaline is the only detectable catecholamine present in rat pericardial fluid. The effect of reserpine 6, 12, and 214 h after pre-treatment with 5 mg kg(-1) (8.2 micromol kg(-1)) i.p. shows that the concentration of noradrenaline in pericardial fluid reflects the amount of noradrenaline released within the heart rather than the amount of noradrenaline in plasma. Using spontaneously hypertensive rats (SHR) as a model for primary hypertension we could show that the level of pericardial noradrenaline is approximately threefold in the pericardial fluid of the SHRs when compared to respective values of age-matched normotensive Wistar-Kyoto rats (WKY), suggesting that there was an increased noradrenaline overflow in the hearts of the SHRs. In conclusion, determination of the noradrenaline concentration in the pericardial fluid might provide a new method for estimating the release of noradrenaline in the heart.

Animals↗
PubMed1969

The effects of reserpine, alpha-methyltyrosine, and L-3,4-dihydroxyphenylalanine on brain tyrosine transaminase.

The effects of a variety of pharmacological and physiological manipulations on the activity of hepatic tyrosine transminase have been extensively investigated. Brain tyrosine transaminase, however, has received only limited attention. Since tyrosine transaminase may be important in the regulation of catecholamine biosynthesis in the brain, the effects of agents affecting catecholamine storage and synthesis on brain tyrosine transamination were investigated. Transamination in the 12,000 x g fraction was measured by a radioactive procedure. alpha-Methyltyrosine and reserpine, agents which deplete brain catecholamines, decreased tyrosine transaminase activity. Administration of the catecholamine precursor, L-3,4-dihydroxyphenylalanine to the reserpine-and alpha-methyltyrosine-treated rats elevated the tyrosine transaminase activity to normal. The possible implications of these findings in the regulation of the biosynthesis of the catecholamines are discussed.

Animals↗