Immunoreactive Growth Hormone Levels in Mice with the Obese-Hyperglycemic Syndrome (Genotype obob)[*]

Abstract

The cause of the pronounced insulin resistance of obesehyperglycemic mice (obob) remains unclear. To evaluate whether growth hormone (GH) is of pathogenetic significance in this context the circulating levels of immunoreactive GH in obese-hyperglycemic mice were compared with those of their lean littermates. In addition, GH was purified from the pituitaries of both types of mice and the molecular size and immunological properties of the hormone from the two sources were compared. It was found that GH from pituitaries of obese and lean mice behaved identically in the different separation steps utilized and produced almost similar elution patterns in molecular sieve chromatography. Strong evidence was obtained also for immunological identity. Assays of circulating immunoreactive GH levels showed that these were similar in the two kinds of mice at 1 and 8 months of age, whereas at 4 and 11-12 months of age there was a significantly lower GH level in the obese-hyperglycemic animals. In view of these findings it appears unlikely that the insulin resistance of the obese-hyperglycemic animals is caused by pituitary hypersecretion of GH.

Key words

Obese Hyperglycemic Mice - Plasma Growth Hormone - Insulin Resistance - Sulfation Factor - Somatomedin

1 Financial aid from The Swedish Medical Research Council and The Swedish Diabetes Association is gratefully acknowledged.

1 Financial aid from The Swedish Medical Research Council and The Swedish Diabetes Association is gratefully acknowledged.