Effect of hydromethanolic extract of Rauvolfia vomitoria leaf on blood glucose, plasma insulin and histomorphology of the pancreas of streptozotocin-induced diabetic male wistar rats

Abstract

Background: Diabetes mellitus is one of the most dreaded health issues worldwide due to its
exponential increasing rate and the limitations of synthetic drugs in providing complete cure
for it, hence, the call by health stakeholders, for more researches on medicinal plants due to
their promising results in providing solutions to some health issues with little or no side effect.
In response to this call, this study investigates the effects of Rauvolfia vomitoria leaf extract on
blood glucose, plasma insulin and histomorphology of the pancreas of diabetic rats in an
attempt to evaluate its anti-diabetic potentials. Methods: Diabetes was induced via
intraperitoneal injection of 55mg/kg b. wt. streptozotocin and treated with hydromethanolic
extract of Rauvolfia vomitoria leaf (250mg/kg and 500mg/kg b. wt. doses) and glyburide
(5mg/kg b. wt.) for 28 days. Blood glucose levels were measured after every 4 days of
treatment during treatment period. Plasma insulin levels were estimated after 14 and 28 days of
treatment via immunoassay; while the histomorphological study was done using hematoxylin
and eosin staining technique. Results: Results from this study show dose dependent significant
(P<0.05) decrease in blood glucose levels and a dose dependent significant increase in plasma
insulin of the extract treated groups which were comparable to those of glyburide treated
group. The histological study of the pancreas showed an improvement on the deranged
pancreas of diabetic rats following 28-days treatment with Rauvolfia vomitoria leaf extract.
This possibly explains the increase in plasma insulin levels and a corresponding decrease in
blood glucose. Conclusion: From the results of this study, it is therefore concluded that
Rauvolfia vomitoria has strong anti-diabetic property. The results show that Rauvolfia
vomitoria leaf extract effect its anti-diabetic action by enhancing the regeneration of the
pancreatic islets thereby increasing insulin secretion and plasma insulin level.