Y. N. Sinha

Pituitary and serum concentrations of prolactin and gh in snell dwarf mice.

Summary Secretions of prolactin and GH in dwarf mice were studied using homologous radioimmunoassays. Blood samples from adult male and female dw/dw mice were collected by orbital puncture and by decapitation. Compared to related normals (+/?), pituitary concentrations of GH and prolactin were very low in dw/dw mice, the concentrations of prolactin being more scarce than those of GH. Prolactin and GH concentrations were also lower in sera of dw/dw mice, but the relative differences appeared sex-dependent: serum GH was more reduced in males than in females while serum prolactin was more depressed in females. The data confirm earlier indications of deficiencies in the circulating levels of prolactin and GH in dwarf mice and suggest that the hypoactivity of these hormones may be crucial to some of the anomalies found in this mutant.

Levels of prolactin, growth hormone and insulin in genetically diabetic (db/db) mice.

Summary Levels of GH, PRL, and insulin in diabetic (db/db) mice 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 weeks of age; the final sample was obtained by decapitation at 32 weeks. 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 to 67% lower in db/db mice at 32 weeks 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 weeks 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 weeks 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.

Serum and pituitary concentrations of growth hormone and prolactin in pygmy mice.

Summary Basal levels of GH and PRL in the serum and pituitary gland of normal (Pg/ Pg) and pygmy (pg/pg) (VY X C3H) F-l hybrid mice were measured by homologous radioimmunoassays. The serum concentrations of GH and PRL in pygmy mice at approximately 90 days of age were found to be no different from those in corresponding normal controls. The pituitary concentrations of the two hormones, however, were substantially subnormal in pygmy mice. Perphena-zine injection failed to stimulate PRL release by pygmy (pg/pg) pituitaries, in contrast to the marked increase in serum PRL levels of the normal Pg/Pg mice. Daily administration of 100 μg of ovine PRL for 8 weeks produced none or very little increase in the body weight of pygmy mice. These results suggest that the pg mutation induces a multifaceted change affecting the synthesis, release, and function of growth hormone and prolactin. The ovine PRL used in these studies was supplied by the Pituitary Hormone Distribution Program of the National Institute of Arthritis, Metabolic, and Digestive Diseases.