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

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Abstract
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.