Effect of cerebrocrast, a new long-acting compound on blood glucose and insulin levels in rats when administered before and after STZ-induced diabetes mellitus

Abstract

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease that is characterized by selective destruction of insulin secreting pancreatic islets beta-cells. The formation of cytokines (IL-1beta, IL-6, TNF-alpha, etc.) leads to extensive morphological damage of beta-cells, DNA fragmentation, decrease of glucose oxidation, impaired glucose-insulin secretion and decreased insulin action and proinsulin biosynthesis. We examined the protective effect of a 1,4-dihydropyridine (DHP) derivative cerebrocrast (synthesized in the Latvian Institute of Organic Synthesis) on pancreatic beta-cells in rats possessing diabetes induced with the autoimmunogenic compound streptozotocin (STZ). Cerebrocrast administration at doses of 0.05 and 0.5 mg/kg body weight (p.o.) 1 h or 3 days prior to STZ as well as at 24 and 48 h after STZ administration partially prevented pancreatic beta-cells from the toxic effects of STZ, and delayed the development of hyperglycaemia. Administration of cerebrocrast starting 48 h after STZ-induced diabetes in rats for 3 consecutive days at doses of 0.05 and 0.5 mg/kg body weight (p.o.) significantly decreased blood glucose level, and the effect remained 10 days after the last administration. Moreover, in these rats, cerebrocrast evoked an increase of serum immunoreactive insulin (IRI) level during 7 diabetic days as compared to both the control normal rats and the STZ-induced diabetic control rats. The STZ-induced diabetic rats that received cerebrocrast had a significantly high serum IRI level from the 14th to 21st diabetic days in comparison with the STZ-induced diabetic control. The IRI level in serum as well as the glucose disposal rate were significantly increased after stimulation of pancreatic beta-cells with glucose in normal rats that received cerebrocrast, administered 60 min before glucose. Glucose disposal rate in STZ-induced diabetic rats as a result of cerebrocrast administration was also increased in comparison with STZ-diabetic control rats. Administration of cerebrocrast in combination with insulin intensified the effect of insulin. The hypoglycaemic effect of cerebrocrast primarily can be explained by its immunomodulative properties. Moreover, cerebrocrast can act through extrapancreatic mechanisms that favour the expression of glucose transporters, de novo insulin receptors formation in several cell membranes as well as glucose uptake.