Protective effect of Gymnema montanum against renal damage in experimental diabetic rats

Gymnema montanum Hook (Asclepiadaceae), is an endemic plant species of India, traditionally used for diabetes and its management. In this experiment, the ethanol extract of G. montanum (GLEt) at a dose of 200 mg/kg body weight was tested to evaluate its effect on renal damage in alloxan-induced diabetic rats and the efficacy was compared with standard hypoglycemic drug, glibenclamide (600 μg/kg body weight). The GLEt and glibenclamide were administered orally for 3 weeks and the effects on glucose, insulin, renal markers including urea, creatinine and uric acid, lipid peroxidation markers including thiobarbituric reactive substances (TBARS) and hydroperoxides and antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities in kidney were studied. In addition, the urinary protein profile was studied using SDS–PAGE. The results indicated that the GLEt significantly normalized the elevated blood glucose, renal markers and lipid peroxidation markers and increased antioxidant levels in diabetic kidney. The diabetic rats excreted large amount of proteins than untreated rats which was normalized during the treatment with GLEt. In conclusion, the GLEt was found to be more effective in reducing oxidative stress, thus confirming the ethnopharmacological use of G. montanum in protecting diabetes and its complications.     

Identification of testosterone-dependent volatile compounds and proteins in the preputial gland of rat Rattus norvegicus

Preputial gland is one of the best known and most odour-producing organs in many non-primate mammals. It is generally believed that the development of this gland and functions are regulated by testosterone. To substantiate this point, the present study was aimed to evaluate the testosterone-dependent volatile compounds and proteins in the preputial gland of rat adopting castration and testosterone supplementation. The results revealed that four compounds, geranyl linalool isomer, oxirane, farnesol and lanosterol, are testosterone-dependent. Similarly, a low molecular mass protein with molecular weight 18 kDa, supposed to be a pheromone carrier, also is shown to be testosterone-dependent. This study leads to the conclusion that testosterone-dependent compounds and sex-associated protein are present in the preputial gland of rat which may act as a sex pheromone and pheromone carrier, respectively.     

Detection of estrus by male mice: Synergistic role of olfactory–vomeronasal system

In rodents, olfactory pathway comprises two distinct systems viz, the main olfactory and vomeronasal systems, both differing in anatomy, physiology and function. The precise role of the main olfactory/vomeronasal system in estrus detection is yet to be explored. Therefore, the present investigation was planned to elucidate the role of main olfactory and vomeronasal system in the estrus discriminating ability of male mice. Female urine samples of proestrus, estrus, metestrus, diestrus, ovarectomized, ovarectomized plus estrogen treated and prepubertal mice were used for the present study. In addition, the urine from intact, castrated and castrated with testosterone treated mice was also tested for odour preference by male mice. The male responders were categorized into three groups namely (a) normal, (b) ZnSO₄-irrigated and (c) vomeronasal organ (VNO)-ablated. The behavioural responses such as frequency and duration of visits to urine samples were carried out in a Y-maze apparatus to assess odour preference. The normal mice displayed more frequent visits to estrus urine samples than to non-estrus samples. In contrast, ZnSO₄-irrigated mice showed significant reduction in the frequency of visits towards estrus urine, whereas, the vomeronasal (VNO)-ablated mice did not show any noticeable preference. With regard to the duration of visits the VNO-ablated mice showed significant reduction in visiting time when compared to ZnSO₄-irrigated mice. This finding indicated that the main olfactory system (MOS) was involved primarily in the attraction from a distance, while the VNO played a major role in close proximity (pre-copulatory behaviour). The males spent less time with the urine of same-sex; however, the response was higher with castrated male urine which was reduced on testosterone treatment indicating that a specific odour in intact male causes aversive behaviour in male. This study provides support to the fact that volatile compounds could also be perceived by VNO, probably when the main olfactory system is in functional state. The study implies that the olfactory–vomeronasal system plays a synergistic role in the detection of estrus.     

Antihyperlipidaemic Effect of Gymnema montanum: A Study on Lipid Profile and Fatty Acid Composition in Experimental Diabetes

Abstract: In the present study, the antihyperlipidaemic efficacy of ethanol extract of Gymnema montanum leaves was investigated in alloxan‐induced diabetic rats and the effect was compared to standard hypoglycaemic drug, glibenclamide. Male adult albino Wistar rats were injected with freshly prepared solution of alloxan monohydrate (150 mg/kg body weight) to induce diabetes. After 2 weeks, the rats with moderate diabetes were administered G. montanum leaves (200 mg/kg body weight) for 21 days by gastric lavage, after which serum, liver and kidney samples were analysed for lipid profile, lipoprotein changes and fatty acid composition. While the alloxan‐induced diabetic rats showed a significant increase in the levels of cholesterol, triglycerides and free fatty acids, the levels in the animals treated with G. montanum leaves were considerably reduced and restored to near normal values. Antihyperlipidaemic effects of G. montanum leaves were found to be comparable with that of glibenclamide. Similarly, G. montanum leaves treatment resulted in reversal of alterations observed in the plasma lipoproteins (high‐density lipoprotein, low‐density lipoprotein and very high‐density lipoprotein‐cholesterol) and fatty acid composition in serum, liver and kidney of alloxan‐induced rats. Our study suggests that phytochemicals present in G. montanum may play an important role in suppressing the elevated lipid profile in diabetes and may be useful for the prevention and/or early treatment of diabetes‐associated hyperlipidaemia.