Dopaminergic, but not cholinergic, involvement in regulation of hypoglycemia-induced oxytocin release in man.
The plasma oxytocin response to insulin-induced hypoglycemia was evaluated in 20 normal male subjects in the basal state (insulin tolerance test (ITT) alone) and after pretreatment with the muscarinic antagonist pirenzepine (40 mg IV 10 min before the ITT in six subjects), the nicotinic antagonist trimethaphan (0.3 mg/min IV for 30 min before the ITT in six subjects), and the dopaminergic receptor agonist bromocriptine (2.5 mg PO 1 hr before the ITT in eight subjects). The drugs did not modify arterial blood pressure nor produce side effects capable of altering oxytocin secretion. Neither pirenzepine nor trimethaphan administration changed the oxytocin response to hypoglycemia, whereas bromocriptine significantly reduced the oxytocin increase during the ITT. These data suggest the involvement of dopaminergic, but not of cholinergic, muscarinic or nicotinic, receptors in the oxytocin response to hypoglycemia.
Chiodera
P
P
Chair of Endocrinology, School of Medicine, University of Parma, Italy.
Gnudi
A
A
Rossi
G
G
Camellini
L
L
Caiazza
A
A
Marchesi
C
C
Bianconi
L
L
Volpi
R
R
Coiro
V
V
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D001971:Bromocriptine; D006801:Humans; D007003:Hypoglycemia / Q000097:blood*; D007328:Insulin; D061389:Insulin, Regular, Pork; D008297:Male; D010121:Oxytocin / Q000097:blood*; D010890:Pirenzepine; D010904:Pituitary Gland, Posterior / Q000502:physiology; D011950:Receptors, Cholinergic / Q000502:physiology*; D011954:Receptors, Dopamine / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000502:physiology; D011978:Receptors, Nicotinic / Q000502:physiology; D014294:Trimethaphan
D001786:Blood Glucose; D007328:Insulin; D061389:Insulin, Regular, Pork; D011950:Receptors, Cholinergic; D011954:Receptors, Dopamine; D011976:Receptors, Muscarinic; D011978:Receptors, Nicotinic; D001971:Bromocriptine; D010890:Pirenzepine; D010121:Oxytocin; D014294:Trimethaphan; C000006:insulin, neutral