[Studies on glucagon secretion in obese rats with hypothalamic lesions (author's transl)]

Glucagon secretion was studied in rats with electrolytic lesions of the bilateral ventromedial hypothalamic area (VMH-L) under various experimental conditions. The results obtained are as follows: 1. The basal plasma level of immunoreactive glucagon (IRG) was lowered in VMH-L rats 5 and 10 weeks after the operation. Plasma IRG levels after 24-hour starvation and during the arginine load were more significantly decreased in the VMH-L rats than in the control group. 2. The basal plasma level of immunoreactive insulin (IRI) showed significant positive correlations with body weight and Lee's index in these rats. The basal plasma level of IRG showed significant negative correlations with body weight, Lee's index and basal plasma IRI level. 3. In response to the arginine load, the plasma IRI level was significantly increased in VMH-L rats immediately after the operation, and the plasma IRG level was more significantly decreased in VMH-L rats 1 week after the operation than in the control group. 4. The response of plasma IRG to the arginine load was also lowered more in VMH-L rats than in rats pair-fed for 4 weeks after the operation. 5. 15 weeks after the operation, there was no significant difference in response of plasma IRI and IRG to the subcutaneous injection of epinephrine between VMH-L and control rats. These findings indicate that hypoglucagonemia in the VMH-L rats was induced by various factors, such as disorder of the autonomic nervous system, excessive insulin release, etc. The impairment of glucagon secretion may contribute to the development of obesity observed in rats with VMH-lesions.