Effects of epidermal growth factor and nerve growth factor on isoproterenol‐induced DNA synthesis in rat parotid and pancreas following removal of submandibular‐sublingual glands

When epidermal (EFG) (10 ng/kg body wt) or nerve growth factor (NGF) (1 ng/kg body wt) was given intraperitoneally to sialadenectomized young rats (submandibular-sublingual (SM-SL) glands removed) prior to injection of isoproterenol (ISO) (50 mg/kg body wt), the inhibition of ISO-induced thymidine incorporation into DNA of parotid gland and pancreas caused by removal SM-SL glands was reversed, and thymidine incorporation of sialadenectomized ISO-treated organs was as high as that of parotid and pancreas of surgically intact animals given ISO. EGF alone caused an increase in [3H] thymidine incorporation into DNA of parotid (63%) and pancreas (59%); removal of the SM-SL glands caused a decrease of 57-70% in thymidine incorporation into DNA of parotid, pancreas, liver, lung, kidney, and spleen. A growth effect attributable to the EGF and NGF of the submandibular gland was thus apparent for all organs examined, but even if they had large complements of beta 1 adrenoceptors, only the exocrine organs showed the ISO-induced beta 1 adrenoceptor response to EGF and NGF. EGF and NGF thus interact only with beta 1 adrenoceptors of exocrine organs to cause marked increase in [3H] thymidine incorporation of these organs.