GROWTH HORMONE-RELEASING HORMONE DEPLETION IN THE FEMALE RAT - SIMILARITIES TO AGING

The age-related decline in growth hormone (GH) secretion has been larg ely attributed to age-related degeneration of hypothalamic growth horm one-releasing hormone (GHRH)-producing neurons. GH decline has recentl y been linked to age-related bone changes in humans. Bone loss and dec reased bone strength are common in aging rats and humans, but density of remaining mineral tissue is known to be increased. The effect of in duced hypothalamic GHRH deficiency on bone was assessed, and similarit ies between bone changes encountered and those taking place in aging w ere identified. Female rats received monosodium glutamate (MSG) follow ing birth, and they were euthanized at 19 weeks of age. Femurs from MS G-treated rats had greater mineral density (p < .05), greater mineral/ matrix ratio (p < .01), lower mineral apposition rate (p < .005), and lower bone formation rate (p < .05). These results suggest that hypoth alamic GHRH decline plays a substantial role in the development of bon e pathology similar to that observed in aging individuals.