[Improvement effect of cinnamaldehyde on reserpine-induced Parkinson's disease rat model].

In order to study the neuroprotective mechanism of cinnamaldehyde on reserpine-induced Parkinson's disease(PD) rat models, 72 male Wistar rats were randomly divided into blank group, model group, Madopar group, and cinnamaldehyde high-, medium-, and low-dose groups. Except for the blank group, the other groups were intraperitoneally injected with reserpine of 0.1 mg·kg~(-1) once every other morning, and cinnamaldehyde and Madopar solutions were gavaged every afternoon. Open field test, rotarod test, and oral chewing movement evaluation were carried out in the experiment. The brain was taken and fixed. The positive expression of dopamine receptor D1(DRD1) was detected by TSA, and the changes in neurotransmitters such as dopamine(DA) and 3,4-dihydroxyphenylacetic acid(DOPAC) in the brain were detected by enzyme-linked immunosorbent assay(ELISA). The protein and mRNA expression levels of tyrosine hydroxylase(TH) and α-synuclein(α-Syn) in substantia nigra(SN) were detected by RT-PCR and Western blot. The results showed that after the injection of reserpine, the hair color of the model group became yellow and dirty; the arrest behavior was weakened, and the body weight was reduced. The spontaneous movement and exploration behavior were reduced, and the coordination exercise ability was decreased. The number of oral chewing was increased, but the cognitive ability was decreased, and the proportion of DRD1 positive expression area in SN was decreased. The expression of TH protein and mRNA was down-regulated, and that of α-Syn protein and mRNA was up-regulated. After cinnamaldehyde intervention, it had an obvious curative effect on PD model animals. The spontaneous movement behavior, the time of staying in the rod, the time of movement, the distance of movement, and the number of standing times increased, and the number of oral chewing decreased. The proportion of DRD1 positive expression area in SN increased, and the protein and mRNA expression levels of α-Syn were down-regulated. The protein and mRNA expression levels of TH were up-regulated. In addition, the levels of DA, DOPAC, and homovanillic acid(HVA) neurotransmitters in the brain were up-regulated. This study can provide a new experimental basis for clinical treatment and prevention of PD.

Developments in biotechnological tools and techniques for production of reserpine.

In the quest for novel medications, researchers have kept on studying nature to unearth beneficial plant species with medicinal qualities that may cure various diseases and disorders. These medicinal plants produce different bioactive secondary metabolites with immense therapeutic importance. One such valuable secondary metabolite, reserpine (C33H40N2O9), has been used for centuries to cure various ailments like hypertension, cardiovascular diseases, neurological diseases, breast cancer, and human promyelocytic leukaemia. Rauvolfia spp. (family Apocynaceae) is an essential reservoir of this reserpine. The current review thoroughly covers different non-conventional or in vitro-mediated biotechnological methods adopted for pilot-scale as well as large-scale production of reserpine from Rauvolfia spp., including techniques like multiple shoot culture, callus culture, cell suspension culture, precursor feeding, elicitation, synthetic seed production, scale-up via bioreactor, and hairy root culture. This review further analyses the unexplored and cutting-edge biotechnological tools and techniques to alleviate reserpine production. KEY POINTS: • Reserpine, a vital indole alkaloid from Rauvolfia spp., has been used for centuries to cure several ailments. • Overview of biosynthetic pathways and biotechnological applications for enhanced production of reserpine. • Probes the research gaps and proposes novel alternative techniques to meet the pharmaceutical industry's need for reserpine while reducing the over-exploitation of natural resources.

Gamma-decanolactone: Preliminary evaluation as potential antiparkinsonian drug.

Treatment of Parkinson's disease (PD) includes the use of monoamine oxidase-B (MAO-B) inhibitor drugs. In this work we have evaluated the possible gamma-decanolactone (GD) effect in vitro to inhibit the A and B isoforms of human monoamine oxidase (hMAO) enzyme and their citotoxicity in human hepatoma cell line (HepG2). Also, binding studies to A1, A2A A2B and A3 adenosine receptors were performed. A docking study of gamma-decanolactone has been carried out with the molecular targets of MAO-A and MAO-B isoforms. The physicochemical properties and ability to cross physiological barriers, as the blood brain barrier (BBB), was elucidated by computational studies. The in vivo assays, the rota-rod test, body temperature assessment and open field test were performed in reserpinized mice (1.5 mg/kg, i.p.; 18:00 before) to evaluate the effect of gamma-decanolactone (300 mg/kg), alone or associated with Levodopa plus Benserazide (LD + BZ, 100:25 mg/kg, i.p.). Gamma-decanolactone inhibited preferentially the MAO-B in a reversible manner, with an inhibitory concentration of 50% (IC50) 55.95 ± 9.06 µM. It was shown to be a safe drug since only at the highest concentration decreased the viability of HepG2 cells. It also does not bind to adenosine receptors investigated in this study. The molecular docking study show that the gamma-decanolactone ligand adopts a relatively compact conformation in the active site of hMAO-B, while we note an extended conformation of gamma-decanolactone ligand in the hMAO-A isoform. The physicochemical properties obtained, and the theoretical models utilized for the evaluation of ability to cross the BBB, predict a good gamma-decanolactone bioavailability and access to the central nervous system (CNS). In the in vivo studies, gamma-decanolactone partially reversed the ataxia of the reserpinized mice at 01:00 h and 01:30 h post-administration. Concomitant treatment of gamma-decanolactone with LD + BZ, at 01:30 h showed a potentiation of the reversibility of ataxia and facilitated the reversal of hypothermia caused by reserpine for all measured times (P <0.01 vs vehicle), except at 24:00 h, but not reversed the hypokinesia in the open field test. In summary, the results herein obtained and in conjunction with previous studies, suggest that gamma-decanolactone could be a drug with potential utility as antiparkinsonian drug.

Desipramine rescues emotional memory deficit induced by low doses of reserpine.

Emotional memory deficit is a well-known complication in early Parkinson's disease. However, its molecular mechanism is still not well known. To address this issue, we examined the cue-related fear-conditioning task and long-term potentiation (LTP) of the thalamus to the lateral amygdala in rats treated with low doses of reserpine (Res). We found that low-dose Res treatment impaired emotional memory and LTP. We also found that exogenous upregulation of norepinephrine (NE) ameliorated the impairment of LTP by facilitating ß-adrenergic receptors. Finally, acute treatment with NE or desipramine rescued the impaired emotional memory induced by a low-dose of Res. These results imply a pivotal role for NE in synaptic plasticity and associative fear memory in rats treated with low doses of Res and suggest that desipramine is a potential candidate for treating Parkinson's disease-related emotional memory deficit.

The metabolism of histamine in rat hypothalamus and cortex after reserpine treatment.

The effect of reserpine on histamine (HA) and tele-methylhistamine (N(τ)-MHA) in hypothalamus and cortex of rats was analyzed and compared to catecholamines. IP injection of reserpine (5 mg/kg) confirmed the effectiveness of reserpine treatment on noradrenaline and dopamine levels. Our in-vitro experiment with synaptosomal/crude mitochondrial fraction from hypothalamus and cortex confirmed that while mono amine oxidase (MAO) is an efficient metabolic enzyme for catecholamines, HA is not significantly affected by its enzymatic action. HMT activity after reserpine, pargyline and L-histidine treatment showed no differences compared to the control values. However HDC was significantly increased in both hypothalamus and cortex. In this study, Ws/Ws rats with deficiency of mast cells were used to clarify aspects of HA metabolism in HAergic neurons by eliminating the contribution of mast cells. The irreversible MAO-B inhibitor Pargyline (65 mg/kg) failed to accumulate N(τ)-MHA in the hypothalamus. However, when animals treated with reserpine and pargyline/reserpine were compared, the last group showed higher N(τ)-MHA values (p < 0.01). Moreover, the precursor of HA, L-histidine (1 g/kg), produced an increase of HA in the hypothalamus to 166% and the cortex to 348%. In conclusion, our results suggest that the effect of reserpine on the HA pools in the brain might be different. The neuronal HA pools are more resistant to reserpine as compared to those of catecholamine. Moreover, the HAergic pool appears to be more resistant to depletion than mast cells' pool, and thus HDC/HMT activity and its localization may play a key role in the understanding of HA metabolism in brain after reserpine treatment.

Green tea modulates reserpine toxicity in animal models.

Reserpine, a natural product extracted from Rauwolfia serpintina or Rauwolfia vomitoria, is a known dopamine depleter that inhibits several neurotransmitters. Reserpine has been used clinically to control hypertension, schizophrenia, insomnia and insanity. The use of this drug, however, has been limited because of its side effects which include oxidative damage to organs, including the liver. Green tea catechins are potent antioxidants that have the potential to counteract reserpine induced oxidative stress. This study investigated the merits of administering green tea concurrently with reserpine to prevent oxidative hepatic damage in Sprague-Dawely (SD) rats. Reserpine was found to cause hepatic damage, with elevated levels of oxidative stress markers, such as Thiobarbituric Acid Reactive Substances (TBARS), transaminases and cholesterol. Reserpine also induced hepatic ultra-structural damage in the cytoplasmic membrane, nuclear envelope, endoplasmic reticulum (rER), ribosomal stripping and mitochondria. Electron microscopy examination showed revival of liver cells as a result of green tea extract administration to experimental rats.

Evaluation of antidepressant-like activity of aqueous and ethanolic extracts of Terminalia bellirica Roxb. fruits in mice.

The present study was undertaken to investigate the effect of aqueous and ethanolic extracts of T. bellirica on depression in mice using forced swim test (FST) and tail suspension test (TST). The extracts were administered orally for 10 successive days in separate groups of Swiss young male albino mice. Aqueous extract (50, 100 and 200 mg/kg) in a dose-dependent manner and ethanolic extract (100 mg/kg) significantly reduced the immobility time of mice in both FST and TST. The extracts were without any significant effect on locomotor activity of mice. The efficacies of aqueous extract (200 mg/kg) and ethanolic extract (100 mg/kg) were found to be similar to that of imipramine (15 mg/kg, po) and fluoxetine (20 mg/kg, po) administered for 10 successive days. Both extracts reversed reserpine-induced extension of immobility period of mice in FST and TST. Prazosin (62.5 microg/kg, ip; an alpha1-adrenoceptor antagonist), sulpiride (50 mg/kg, ip; a selective D2 receptor antagonist) and p-chlorophenylalanine (100 mg/kg, ip; an inhibitor of serotonin synthesis) significantly attenuated the aqueous and ethanolic extract-induced antidepressant-like effect in TST. Thus, both the aqueous and ethanolic extracts of T. bellirica elicited a significant antidepressant-like effect in mice by interaction with adrenergic, dopaminergic and serotonergic systems.

Autoradiographic localization of [3H]reserpine binding sites in rat brain.

[3H]Reserpine was administered (i.v.) to rats and they were killed 7 days later. At this time, the regional localization of radioactivity paralleled the distribution of specific binding sites observed in other laboratories. Autoradiographic studies of certain areas displayed a striking localization of radioactivity. There was a marked association of autoradiographic grains with areas containing catecholamine systems. In particular, the locus ceruleus, the caudate-putamen, the nucleus accumbens, the dorsolateral septum and the infundibulum had high grain densities. In the caudateputamen, there was a clear localization of grains to the neuropil. There was also a striking association of autoradiographic grains with certain hypothalamic nuclear, i.e., the dorsal premammillary nucleus, the prelateral mammillary nucleus and the lateral mammillary nucleus. In these areas, the grains were clearly localized in the cytoplasm of the cell bodies. All of the above localizations of autoradiographic grains were blocked by administration of unlabeled reserpine before injection of [3H]reserpine. The significance of these findings and their relationship to the clinical actions of reserpine are discussed.

[Interactions between oxygen under high pressure and drugs (author's transl)]. / Wechselwirkungen zwischen hyperbarem Sauerstoff und Arzneimittel

A. The clinical applications of oxygen under high pressure (OHP) are limited by oxygen toxicity. Hence, an investigation was carried out in mice on the influence of drugs on the lethal effect of OHP. 1. The lethal effect of OHP is diminished by phenobarbitone, propranolol, clonidine, succinate and tris buffer. 2. The lethal effect of OHP is enhanced by methamphetamine, acetazolamide and guanethidine. 3. The lethal effect of OHP is enhanced by reserpine two hours after administration, but diminished 12 hours after administration. B. The clinical usage of OHP is often necessarily connected with drug therapy. Hence, alteration in drug effects under OHP were investigated in mice and rats. 1. The convulsion threshold of pentetrazol is reduced under OHP by 26%. 2. The duration of the hypnotic effect of hexobarbitone is reduced under OHP by 27%. 3. The analgesic effect of morphine is unchanged by OHP. Practical aspects with regard to the use of drugs during clinical use of OHP are discussed.

The biological fate of reserpine.

Orally administered reserpine is readily absorbed from the GI tract. During this process at least a portion of the drug is metabolized by the intestinal mucosa and then presumably is acted upon by serum esterases. Methylreserpate and trimethoxybenzoic acid are the primary metabolites which result from the hydrolytic cleavage of reserpine. Since most of the blood leaving the GI tract passes through the liver via the portal vein, hepatic metabolism would also be expected to reduce reserpine levels in the blood. The relative contributions of serum esterases versus hepatic metabolism in the biotransformation of reserpine in vivo are not known. However, very little unmetabolized reserpine is eventually eliminated in the urine. In the liver, it is quite likely that both microsomal oxidative and hydrolytic enzymes contribute to the metabolism of reserpine. It seems that microsomal oxidation (such as the demethylation of the 4-methoxy group on the TMBA moiety) must precede hydrolysis since inhibition of demethylation markedly reduces the rate of hydrolysis. In addition to oxidation and hydrolysis, conjugative reactions also must occur in liver or extrahepatic tissues since both glucuronide and sulfate conjugates of TMBA have been identified. Some reserpine molecules do seem to escape metabolism, however, since significant amounts of intact reserpine have been found in fecal samples taken from both experimental animals and human beings after either oral or parenteral drug administration. Presumably reserpine is transported from the blood via the biliary tree into the small intestine where it is either reabsorbed or eliminated in the feces. Pulmonary elimination of CO2 produced after complete oxidation of the 4-methoxy group of TMBA has also been shown to occur both in vivo and in vitro. The following may serve as a model for the relationship between the subcellular distribution of reserpine and its site of action. After a single intravenous injection most of the reserpine, probably loosely bound to plasma albumin, is distributed to tissues on the basis of their blood flow. Because of its lipophilic properties, reserpine would easily penetrate cell membranes and then bind possibly electrostatically to intracellular membrane components, particularly those rich in phospholipids. Much of the circulating reserpine would then either be metabolized or be taken up by the lipid depots of the body, leading to a rapid redistribution of the reversibly bound reserpine from the tissues. During this time a relatively small fraction of the total reserpine administered by injection would become associated with monoaminergic granular membranes in a more specific and irreversible manner. This would result in a persistent, nonstoichiometric inhibition of monoamine uptake. Such a small specific binding would not be detectable for at least 18 hr after reserpine administration, i.e., until most of the reversibly bound alkaloid had been metabolized and/or excreted...