Screening of Indian plants for biological activity: Part XVI.

Alcoholic extracts of 288 of plant materials from 199 plant species have been tested for various biological activities including chemotherapeutic and pharmacological screening. Biological activities, ranging from moderate to good degree, have been observed in 61 plants extracts. Follow up studies have been carried out in these extracts and some of them have shown moderate degree of activities at this Institute. However, none of the extracts was found to be good enough for further development. Results of the present studies, along with chemical investigations on different species of similar genera which were screened earlier, are also discussed.

Behavioural and anti-psychotic effects of Ca2+ channel blockers in rhesus monkey.

The potential utility of Ca2+ channel blockers in the treatment of various psychiatric disorders has been recently suggested. In the present study, the behavioural and anti-psychotic effects of Ca2+ channel blockers were investigated in unrestrained rhesus monkeys (Macaca mulatta) living together in a colony. The different behaviours categorised as social, solitary and abnormal were video recorded and analysed. Graded doses of verapamil (5-20 mg/kg, i.m.) and nimodipine (7.5-30 mg/kg, p.o.) produced a mild decrease in social and solitary behaviour without producing any cataleptic posture in the tested monkeys. In order to determine potential antipsychotic effects, Ca2+ channel blockers were studied in the model of amphetamine-induced psychosis. Amphetamine, at the dose of 2 mg/kg, i.m., induced suppression of approach, contact, grooming, and feeding, whilst vigilance (checking), stereotyped behaviour and oral hyperkinesia were increased in the monkeys. Pre-treatment with verapamil (10 and 20 mg/kg, i.m.) significantly suppressed amphetamine-induced hypervigilance, stereotypy, oral hyperkinesia and tachypnoea but was unable to reverse other amphetamine-induced behavioural effects. Nimodipine showed insignificant anti-psychotic effects at both 15 and 30 mg/kg doses. These results suggest that verapamil has a definite antipsychotic effect without any extrapyramidal side effects and thus may be of clinical significance in the treatment of psychosis.

The hamster heart is resistant to calcium paradox.

Reintroduction of Ca(2+)or modification of internal Ca(2+)stores by caffeine results in widespread irreversible injury. The adult golden hamster, however, is immune to such insult and the present report investigates the phenomenon. Isolated Langendorff perfused hamster and rat heart were subjected to 15 min Ca(2+)-free perfusion followed by 30 min of Ca(2+)perfusion at 37 degrees C. Caffeine was introduced during Ca(2+)-free perfusion in a number of experiments. Papillary muscles were processed for the ultra-structural study. The hamster heart did not exhibit the calcium paradox state whereas rat heart did. Hamster heart treated with caffeine either throughout or 5 min after starting Ca(2+)-free perfusion showed 70%+/-8 or 65%+/-8. 42 recovery, respectively, when Ca(2+)reperfusion was performed. Ultrastructure of muscle from both groups showed relaxed myocytes with slight disorientation of the sarcomere register. This disorientation was not seen in hamster hearts undergoing the conventional calcium paradox protocol. The hamster cardiac muscle is remarkably tolerant to [Ca(2+)]()i loading either induced by Ca(2+)reperfusion or caffeine-induced sarcoplasmic reticulum Ca(2+)release. Structural and functional characterization of Ca(2+)depletion and repletion in the hamster heart have been discussed.

The hamster heart: a paradox in itself.

Perfusion of all mammalian heart muscle except hamster with Ca(2+)-free Tyrode and thereafter reperfusion with normal Tyrode causes irreversible damage, the calcium paradox. Our study aims at deciphering the role of creatine kinase, high energy phosphates and Ca(2+)influx in the genesis of myocardial injury in the rat and comparing it with the hamster. Isolated hearts from hamster and rats were perfused in the Langendorff mode at 37 degrees C for 30 min with normal Tyrode, for 15 min with Ca(2+)-free Tyrode and thereafter for 30 min of reperfusion with normal Tyrode. The 'high energy phosphate compound' levels were monitored by(31)P-NMR, creatine kinase (CK) release was measured in the perfusate.(45)Ca influx was estimated in the papillary muscle. We observed that in the rat heart: (a) high energy phosphate levels declined significantly within 1 min of Ca(2+)reperfusion; (b) a massive release of CK occurred upon Ca(2+)reperfusion; (c) there was a significant increase of Ca(2+)influx. In the hamster heart, there was preservation of high energy phosphates, CK release was prevented completely and no rise in(45)Ca influx was observed upon Ca(2+)reperfusion. These results suggest that the hamster heart has a remarkable capacity for Ca(2+)homeostasis which protects the heart from Ca(2+)overload.

Immunomodulatory effect of albizzia lebbeck.

The immunomodulatory effect of the bark of Albizzia lebbeck (Sirisha) was evaluated by studying humoral and cell mediated immune responses. The hot aqueous extract and its butanolic fraction were administered once daily for one week in mice, immunised previously with sheep red blood cells (SRBC). At the dose levels tested (6.25, 12.5 and 25 mg/kg, p.o.), A. lebbeck treated mice developed higher serum antibody titres compared to the vehicle treated group and the effect was comparable to the standard drug muramyl dipeptide (MDP). Delayed type hypersensitivity response was suppressed in SRBC immunised mice treated with A. lebbeck extract. The macrophage migration index remained unaltered in both mice and rats. These results are discussed in the light of possible immunopotentiating effects of A. lebbeck.

Cholinergic and serotonergic alterations in the rat hippocampus following trimethyltin exposure and fetal neural transplantation.

Trimethyltin (TMT) apart from causing cholinergic denervation of the hippocampus, damages the serotonergic inputs into the hippocampus as well. In the present study, fetal cholinergic and serotonergic rich neuronal populations from septal and raphe regions, respectively, were transplanted alone or in combination (as co-grafts) in the hippocampus of TMT exposed rats. Neurotransmitter receptor binding and neurotransmitter levels were assayed 6 months post-transplantation. Fetal septal transplants (rich in cholinergic neurons) significantly restored the deficits in cholinergic (muscarinic) receptor binding and acetylcholinesterase activity caused by TMT exposure. Raphe transplants (rich in serotonergic neurons) restored the deficit in serotonergic receptor binding and serotonin levels caused by TMT. Co-grafts of fetal raphe and septal neurons restored both the cholinergic (muscarinic) and serotonergic receptor functions. The results suggest that co-grafting technique could provide a better restoration of functional deficits when more than one type of neuronal population is damaged.

Healing potential of Calotropis procera on dermal wounds in Guinea pigs.

Calotropis procera (Asclepiadaceae) is a well known plant in the Ayurvedic system of medicine. Based on its traditional use this plant was selected for evaluation of its wound healing potential. For this purpose four full thickness excisional wounds of 8.0 mm diameter were inflicted on the back of guinea pigs. Topical application of 20 microl of 1.0% sterile solution of the latex of C. procera twice daily was followed for 7 days. The latex significantly augmented the healing process by markedly increasing collagen, DNA and protein synthesis and epithelisation leading to reduction in wound area. Thus the present study provides a scientific rationale for the traditional use of this plant in the management of wound healing.

Differential expression of proteins during healing of cutaneous wounds in experimental normal and chronic models.

Recent studies have demonstrated growth factors and other cellular proteins as being important in the healing process. In this study, we have investigated the differential expression of proteins in wound tissues of normal and chronic animal models. Proteins were identified by specific antibodies, partial N-terminal amino acid sequence, and molecular weight homology. In normal wound tissues de novo synthesis of a heat shock protein, platelet derived growth factor (PDGF), and fibroblast growth factor (FGF) was induced within 24 h of skin injury. Proteins resembling vascular endothelial growth factor, receptors for PGDF, FGF, and epidermal growth factor, were synthesized. The elevated synthesis declined to a basal level in 7 to 14 days after skin injury which coincided with healing of wounds. These changes occurred only in wound site tissues but not in distal tissues. In contrast, the chronic wounds presented a different picture. The expressions of these proteins were either delayed or inhibited. This suggested the role of these proteins during normal and chronic wound healing. The proteins which were down regulated in chronic wounds may be used in the management of wounds and exploited as targets for therapeutic development.

Csf 5 - hiaa in violent and non-violent suicide attempters.

Many studies have reported involvement of monoamine neurotransmission in suicide through measurement of serotonin and its main metabolite, 5-HIAA, in brain of suicide victims and in CSF of suicide attempters. 23 non-depressed non-psychotic suicide attempters and equal number of controls were selected, and all the subjects were screened on Cornell Medical Index. Suicide attempters were assessed on Risk-Rescue Rating Scale and were divided into non-violent suicide attempters (N= 12) and violent suicide attempters (N= II). CSF of all subjects was collected by lumbar puncture and CSF 5-HIAA was measured by high performance liquid chromatography with electro-chemical detector. Risk-rescue rating score was significantly higher in violent suicide attempters as compared to non-violent suicide attempters. Mean CSF- 5- HIAA was significantly lower in suicide attempters as compared to normal controls. Mean CSF 5-HIAA was significantly lower in violent suicide attempters as compared to non-violent suicide attempters.

Modulation of 5-HT1C receptors and phosphoinositide system by ethanol consumption in rat brain and choroid plexus.

The effect of chronic ethanol consumption (60 days) on 5-HT1C receptors as measured by [3H]mesulergine binding in the hippocampus, cortex, and choroid plexus of rats was investigated. The 5-HT1C receptor-mediated phosphoinositide hydrolysis in rat choroid plexus was also investigated. It was observed that chronic ethanol treatment significantly increased the 5-HT-stimulated [3H]inositol 1-phosphate ([3H]IP1) formation, as well as the density (Bmax) of 5-HT1C receptors without causing a significant change in affinity (KD) of [3H]mesulergine binding in rat choroid plexus. It was also observed that chronic ethanol consumption had no significant effect on the Bmax or KD of 5-HT1C receptor binding sites in the hippocampus and cortex brain regions of rats. These results thus suggest that chronic ethanol consumption causes an up-regulation of both 5-HT1C receptors and 5-HT1C receptor-mediated phosphoinositide hydrolysis in rat choroid plexus but has no significant effects on the 5-HT1C receptors in brain. These results also suggest that 5-HT1C receptors and their functional response may be involved in the pathogenesis of alcohol dependence.

Comparative neurotoxicity of cadmium in growing and adult rats after repeated administration.

The effect of cadmium administration (Cd 0.4 mg/kg, ip, intraperitoneally, daily for 30 days) on its accumulation, contents of 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) in different brain regions in growing and adult rats was investigated. Cadmium was found to significantly increase the levels of 5-HT and 5-HIAA in all the brain regions of adult rats while the levels of 5-HT and 5-HIAA were significantly decreased in most of the brain regions of growing rats. The accumulation of cadmium in all the brain regions was significantly more marked in growing rats compared to adults after identical exposure. In conclusion, there was an age difference in both the accumulation of cadmium and 5-HT turnover in the brain regions. However, the regional neurochemical changes were not correlated with the magnitude of cadmium accumulation in both the groups.

Effect of centhaquine on spontaneous and evoked norepinephrine release from isolated perfused rabbit heart.

1-[Bis(2-quinolyl)-ethyl]-4-m-tolylpiperazine (centhaquine), a centrally acting hypotensive agent, was studied for its effect on spontaneous and evoked release of norepinephrine (NE) from the rabbit heart. Spontaneous release of NE as well as its release evoked by potassium chloride (81 X 10(-3) mol/l), tyramine hydrochloride (2.88 X 10(-5) mol/l), dimethyl phenyl piperazinium iodide (DMPP, 3.18 X 10(-5) mol/l), acetylcholine chloride (1 X 10(-4) mol/l) and amphetamine sulfate (7.48 X 10(-5) mol/l) from isolated perfused rabbit heart was studied. Centhaquine (0.1, 1.0 and 10.0 micrograms/ml) caused an initial increase followed by inhibition of spontaneous NE output. It also significantly inhibited the NE release evoked by KCl, DMPP and acetylcholine but not tyramine and amphetamine evoked release. It is concluded that centhaquine predominantly inhibits the neuronal NE release.

Supra spinal influence on ventricular fibrillation threshold and cardiac stores of norepinephrine in the cat.

The relationship between ventricular fibrillation threshold (VFT) as measured by voltage required to evoke ventricular fibrillation and the concentration of norepinephrine (NE) in different parts of the myocardium under experimental interventions has been studied in anaesthetized cats. A selective increase in VFT and a marked reduction in NE content have been observed after spinal transection, removal of spinal cord from cervical 6 to thoracic 6 or carotid sinus denervation. Reserpine pretreatment significantly reduces NE content of myocardium but fails to affect VFT. The fibrillating left ventricle shows a marked decline in NE content from the control level of 1.55 +/- 0.32 to 0.82 +/- 0.09 micrograms/g and there is also a similar concomitant reduction in NE content of the entire heart. Defibrillation brings back normal rhythm, but does not restore the NE content immediately. The results suggest that a marked reduction in cardiac stores of norepinephrine significantly affect VFT and that the central nervous system plays an important role in the genesis of sustained ventricular arrhythmia.

Pharmacological studies on coleonol, a hypotensive diterpene from Coleus forskohlii.

Coleus spp. have been used in Aurvedic medicine for heart diseases, spasmodic pain, painful micturition and convulsions. The pharmacological properties of coleonol, a diterpene, isolated from Coleus forskohlii were investigated. Its predominant effect is to lower the blood pressure of anaesthetised cat and rat as well as of the spontaneously hypertensive rat due to relaxation of the vascular smooth muscle. In small doses it has a positive inotropic effect on isolated rabbit heart as well as on cat heart in vivo. Coleonol also exhibits nonspecific spasmolytic activity on smooth muscle of the gastrointestinal tract in various species but not on bronchial musculature of guinea pig. Large doses of coleonol have a depressant action on the central nervous system. These results provide the rationale for the use of this plant in Aurvedic medicine.