Evidence for direct effect of growth hormone on capillary basement membrane thickness.

Abstract

In order to investigate the direct effect of growth hormone on the capillary basement membrane thickness (CBMT), we performed, in normal and diabetic rats, ultrastructural morphometric studies on the capillaries of the skin loci where the intracutaneous injections of physiologic saline and human growth hormone (HGH) in various concentrations had been repeated daily for 28 days. In the normal group, the injection (0.1 ml daily) of HGH solutions in concentrations of 0.5 ,u g/ml and 2 ,u g/ml did not significantly alter the CBMT, and only at the concentration of 10,ug/ml, HGH significantly (p <0.001) increased the CBMT. In the diabetic group, however, the injection of any of the HGH solutions significantly (p <0.001 0.05) increased the CBMT. In another diabetic rat series, HGH, human albumin, humam menopausal gonadotropin and human globulin (each in a concentration of 10 pg/ml) were repeatedly injected into four separate skin portions for 28 days, and it was found that the net increase in CBMT was most striking in the HGH-treated portion. These data demonstrated the direct and specific effect of HGH on CBMT diabetic microangiopathy ; basement membrane thickness ; growth hormone Although the multiple factors have been recognized in the genesis of diabetic microangiopathy, a specific role of growth hormone in the progression of the microangiopathy has been emphasized by colleagues (1970, 1971). In fact, a remission of diabetic retinopathy was observed after hypophysectomy (Luft et al. 1955) and diabetic microangiopathy could not be demonstrated in pituitary dwarfs with grossly abnormal glucose tolerance (Merimee et al. 1970).Recently, (~sterby et al. (1978) reported that porcine growth hormone administered intramuscularly for 20-40 days increased significantly the glomerular basement membrane thickness in diabetic rats, though they could not clarify