Simulation of the apparent effects of mebanazine on growth hormone by pair-feeding of control animals

Abstract

Abstract The degree and duration of insulin hypoglycaemia was potentiated by chronic oral medication with mebanazine in rats. Hypophysectomy alone increased sensitivity to insulin but did not abolish the potentiating effect of mebanazine. Chronic mebanazine treatment (15 mg/kg/day) for 6 weeks markedly reduced weight gain, food and water consumption and pituitary growth hormone content, but the results were not significantly different from those in unmedicated pair-fed controls. Similarly, immature rats treated with mebanazine had a significant reduction in the width of the tibial epiphysial cartilage but this was not different from that in pair-fed animals. After 18 h of fasting, acute administration of mebanazine had little effect on food consumption in the 2 h period following dosing but a significant effect over 24 h. In fed rats mebanazine in a single oral dose significantly reduced eating in the following 6 h. Treatment with mebanazine at 2·5 mg/kg for 15 days significantly reduced food intake but did not potentiate insulin hypoglycaemia. From the results it would appear that previous suggestions that mebanazine specifically interferes with growth hormone release are incorrect and the findings emphasize the importance of measuring food intake in experiments of long duration.