Levels of Prolactin, Growth Hormone and Insulin in Genetically Diabetic (db/db) Mice

Abstract

GH [growth hormone], PRL [prolactin] and insulin levels were studied by radioimmunoassay. Serial blood samples from normal and diabetic mice of both sexes were obtained by orbital puncture at 5, 7, 10, 15, 20, 24 and 28 wk of age; the final sample was obtained by decapitation at 32 wk. Serum insulin and glucose levels in db/db mice were higher than normal throughout the study. Compared to those in normal controls, GH and PRL concentrations in the pituitary gland were 33-67% lower in db/db mice at 32 wk of age. Serum GH levels in orbitally collected samples were also markedly subnormal in male diabetics; in females, the differences were not significant. GH levels in sera collected at 32 wk were not significantly different from those of controls in either sex. PRL concentrations in the orbitally collected sera of db/db mice were lower than normal until 10-12 wk of age; after this age the values approached normal levels. PRL concentrations in sera collected at decapitation were significantly lower than normal in db/db mice of both sexes. A single injection of perphenazine elicited a 20-fold rise in serum PRL concentrations in normal females; in db/db females, there were no increases. The results suggest generally deficient secretion of GH and PRL in the mutant db/db mouse.