Effects of corticotropin-releasing hormone on insulin and glucagon secretion in mice

Besides in the brain, corticotropin-releasing hormone occurs in the pancreas. Therefore, its effects on plasma levels of insulin and glucagon were investigated in vivo in the mouse. At 2 min after CRH injection (0.5-8.0 nmol/kg), plasma insulin was lowered: by 4.0 nmol/kg from 38 +/- 4 to 28 +/- 2 mU/l (P less than 0.05). Plasma insulin was lowered also at 6 min, whereas at 10 min, plasma insulin levels were elevated (P less than 0.05). Plasma glucagon levels were slightly lowered (P less than 0.05) at 10 min after CRH injection, whereas plasma glucose was slightly elevated (P less than 0.05) at 6 min after injection but not at 2 or 10 min. The effects of CRH on the plasma insulin and glucagon response to iv injections of half-maximal dose levels of glucose (2.8 mmol/kg) or the cholinergic agonist carbachol (0.16 mumol/kg) were also investigated. CRH, 4.0 nmol/kg, however, could not influence the plasma insulin or glucagon levels after the iv injection of either glucose or carbachol. Thus, CRH slightly affects basal plasma levels of insulin and glucagon in mice. In contrast, stimulated insulin and glucagon secretions are not affected by CRH. Peripheral CRH may therefore be of slight importance for the regulation of basal plasma levels of insulin and glucagon in the mouse.