Six-month follow-up in weanling rats with ventromedial and dorsomedial hypothalamic lesions: somatic, endocrine, and metabolic changes

Abstract

Thus far both the weanling rat ventromedial and dorsomedial syndrome have been investigated in only two and three-week studies. The present data are derived from a six-month study. Food intake and body weight and length changes were recorded weekly or bi-weekly and endocrine and metabolic parameters were assessed at sacrifice. Rats that had received ventromedial hypothalamic lesions shortly after weaning showed all the changes noted in previous short-term studies, i.e. normal body weight gains and food intake but increased carcass fat content. In addition, they manifested a slight hyperglycemia, normal free fatty acid levels and slowingdown of lipogenesis. Rats that had received dorsomedial lesions shortly after weaning also showed changes previously reported in short-term experiments. These include reduced ponderal and linear growth and food intake, but normal carcass composition and growth hormone levels. In addition, they showed a slight improvement of hypophagia with time, and at sacrifice hypoglycemia and low free fatty acid levels. Incorporation of glucose into fat pad glycogen and CO2 was decreased. In diaphragm, glucose incorporation was increased in both total lipid and fatty acids. The data demonstrate that both hypothalamic syndromes change with time, but not necessarily in a progressive manner. They also show that destruction of two so closely appositioned hypothalamic structures brings about entirely different and, in some parameters, opposite changes.