ASSESSMENT OF THE PRIMARY ADRENAL-CORTICAL AND PANCREATIC HORMONE BASAL LEVELS IN RELATION TO PLASMA-GLUCOSE AND AGE IN THE UNSTRESSED AMESDWARF MOUSE

Peripheral glucose concentrations in mammals are maintained within ver y narrow limits to provide a continuous, uninterrupted supply of this nutrient to tissues, Numerous factors have been shown to influence and /or regulate glucose levels, One such influence is growth hormone (GH) produced by the pituitary somatotrophs, Several animal models of hypo somatotropism are available in which GH secretion or actions are suppr essed due to genetic abnormalities, One such model, the Ames dwarf mou se (df/df), has arisen from an autosomal recessive mutation in which G H-, prolactin- (PRL), and thyroid-stimulating hormone (TSH)-producing cell types of the anterior pituitary fail to develop, The current inve stigation examined the effects of GH deficiency on glucose, insulin, a nd corticosterone levels using male and female df/df mice and their no rmal (Df/-) littermates, Additionally, old and young females of both g enotypes were used to determine whether aging and GH deficiency intera ct to influence insulin, corticosterone or glucose levels in these ani mals, Plasma samples collected from unstressed animals (normal, df/df; young [5 months], old [17-19 months]; male, female) were used, Glucos e levels were lower (P < 0.05) in df/df than in Df/- mice regardless o f sex and age, A sex difference in Df/- animals was evident-young and old females had significantly lower levels of glucose when compared wi th young Df/- males, Plasma insulin was elevated (P < 0.05) in old df/ df females compared with young df/df and Df/- females, Young Df/- male s had the highest insulin levels compared with all genotype and age gr oups. This observation paralleled results from glucose measurements, C orticosterone levels were highest in young Df/- females and lowest in young Df/- males, with df/df animals falling between these values, Pla sma corticosterone levels in old Df/- females did not differ from the values measured in dwarfs, The present findings indicate that glucose and factors affecting glucose levels are altered in the df/df mouse, T hese results provide new insights into the roles GH may play in glucos e metabolism and perhaps also in adiposity which is a common character istic of Df/- aged females from this line of mice.