Hypoglycemic effects of Cecropia pachystachya in normal and alloxan-induced diabetic rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Leaves of Cecropia pachystachya are described in the folk medicine as possessing antitusive, expectorant, antiasthmatic and hypoglycemic effects. AIM OF THE STUDY: To investigate the hypoglycemic and antioxidant effects of methanolic extract from the leaves of Cecropia pachystachya. The total amount of phenolic and flavonoids compounds was determined and the qualitative composition of the extract was analyzed. MATERIALS AND METHODS: The hypoglycemic effect of the extract was tested in normal, glucose loading and alloxan-induced diabetic rats. The antioxidant activity was assessed by DPPH free radical scavenging and reduction power assays. The total amount of phenolic and flavonoids compounds was determined by Folin-Denis and AlCl(3) reagent method, respectively. The qualitative composition of the extract was analyzed using a HPLC-DAD system. RESULTS: The glucose tolerance test showed that in diabetic rats, the extract caused a significant hypoglycemic effect with a blood glucose reduction of 68% after 12h. The administration of the extract in alloxan-induced diabetic rats also produced a significant reduction in the blood glucose levels at all points being more pronounced at 90min (reduction of 60%). After 120min, no significant difference was observed between the blood levels of the rats treated with the extract and those treated with the standard drugs (metformin and glibenclamide). The extract also presented relevant antioxidant activity with IC50=3.1microg/ml (DPPH assay) and EC50=10.8microg/ml (reduction power). Results were compared with the reference antioxidants quercetin, rutin, and ascorbic acid. The content of flavonoids was 83mg/g plant and that of phenolics was 326mg/g plant. Chlorogenic acid and the C-glycosylated flavones, orientin and isoorientin, were identified in the extract. CONCLUSIONS: In conclusion, the findings showed that the folk medicinal plant Cecropia pachystachya possesses hypoglycemic and antioxidant effects which confirmed the traditional use of the plant in the treatment of diabetes. Chlorogenic acid and the C-glycosylated flavonoids may explain these activities.

Adrenal medullary function and expression of catecholamine-synthesizing enzymes in mice with hypothalamic obesity.

The mechanisms underlying the onset of obesity are complex and not completely understood. An imbalance of autonomic nervous system has been proposed to be a major cause of great fat deposits accumulation in hypothalamic obesity models. In this work we therefore investigated the adrenal chromaffin cells in monosodium glutamate (MSG)-treated obese female mice. Newborn mice were injected daily with MSG (4 mg/g body weight) or saline (controls) during the first five days of life and studied at 90 days of age. The adrenal catecholamine content was 56.0% lower in the obese group when compared to lean controls (P < 0.0001). Using isolated adrenal medulla we observed no difference in basal catecholamine secretion percentile between obese and lean animals. However, the percentile of catecholamine secretion stimulated by high K+ concentration was lower in the obese group. There was a decrease in the tyrosine hydroxylase enzyme expression (57.3%, P < 0.004) in adrenal glands of obese mice. Interestingly, the expression of dopamine beta-hydroxylase was also reduced (47.0%, P < 0.005). Phenylethanolamine N-methyltransferase expression was not affected. Our results show that in the MSG model, obesity status is associated with a defective adrenal chromaffin cell function. We conclude that in MSG obesity the low total catecholamine content is directly related to a decrease of key catecholamine-synthesizing enzymes, which by its turn may lead to a defective catecholamine secretion.