Acute in-vivo effects of adrenocorticotrophin on plasma levels of glucagon, insulin, glucose and free fatty acids in rabbits: involvement of the alpha-adrenergic nervous system.
Intravenous injection of 8.5 nmol (1-24)ACTH increased the plasma levels of glucagon, insulin, glucose and free fatty acids in rabbits. The (1-24)ACTH-induced hyperglucagonaemia and hyperinsulinaemia started 3 and 20 min after the injection respectively. Similar increases in the plasma levels of glucagon, insulin and free fatty acids were found with 5.3 nmol (1-39)ACTH, whereas (1-4)ACTH, (4-10)ACTH, (1-10)ACTH, (11-24)ACTH, (7-38)ACTH and (18-39)ACTH (corticotrophin-like intermediate lobe peptide) injected at doses of approximately 8 nmol were inactive. Infusions with the alpha-adrenergic blocking drug, phentolamine, reduced the (1-24) ACTH-induced hyperglucagonaemia and hyperglycaemia, and augmented the (1-24)ACTH-induced hyperinsulinaemia, which now became significant after 5 min. Infusions with the beta-adrenergic blocking drug, propranolol, did not diminish the (1-24)ACTH-induced effects, but killed the rabbits after 2-4 h. It is concluded that the acute in-vivo effects of ACTH in rabbits are modulated by the involvement of alpha-adrenergic receptors, which increased the plasma levels of glucagon and glucose, and delayed and diminished the ACTH-induced increases in the plasma levels of insulin. The (1-24)ACTH-induced increases in the plasma levels of free fatty acids were not influenced by the adrenergic blocking drugs.
D000324:Adrenocorticotropic Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D003366:Cosyntropin / Q000494:pharmacology*; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D005260:Female; D005934:Glucagon / Q000097:blood*; D007275:Injections, Intravenous; D007328:Insulin / Q000097:blood*; D010446:Peptide Fragments / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011817:Rabbits; D011941:Receptors, Adrenergic / Q000187:drug effects*
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D010446:Peptide Fragments; D011941:Receptors, Adrenergic; D003366:Cosyntropin; D000324:Adrenocorticotropic Hormone; D005934:Glucagon; D011433:Propranolol; D010646:Phentolamine