tGLP-1 action on the isolated hypothalamo-neurohypophysial system under glutamate receptor blockade.
The isolated rat hypothalamo-neurohypophysial system was used to investigate possible mechanisms of glucagon-like peptide-1 (7-36) amide (tGLP-1) effects on the vasopressin/oxytocin (AVP/OXY) release. The non-selective inhibition of synaptic transmission as brought about by excess of MgSO(4) in the incubation medium completely abolished the tGLP-1-induced AVP release and attenuated OXY secretion. The non-specific blockade of excitatory amino acid receptors with kynurenic acid (KA) completely suppressed the tGLP-1-induced AVP but not OXY release. Specific inhibition of NMDA receptors suppressed the tGLP-1-evoked AVP release without affecting tGLP-1-induced OXY secretion. Selective blockade of non-NMDA receptors did not affect either tGLP-1-induced AVP or OXY release. It is concluded that tGLP-1 can influence the function of AVP neurons indirectly, most probably via the glutamatergic system through NMDA receptors. On the other hand, tGLP-1-evoked activation of OXY neurons, at least in part, seems to be a result of direct tGLP-1 activation of these neurons.
Bojanowska
Ewa
E
Department of Pathophysiology, The Medical University of Lodz, Lodz, Poland.
Stempniak
Bozena
B
D000818:Animals; D001127:Arginine Vasopressin / Q000096:biosynthesis / Q000378:metabolism; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D005934:Glucagon; D052216:Glucagon-Like Peptide 1; D004763:Glucagon-Like Peptides; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D010121:Oxytocin / Q000096:biosynthesis / Q000378:metabolism; D010446:Peptide Fragments; D010455:Peptides / Q000494:pharmacology* / Q000502:physiology; D010913:Pituitary-Adrenal System / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017470:Receptors, Glutamate / Q000378:metabolism*
D018691:Excitatory Amino Acid Antagonists; D010446:Peptide Fragments; D010455:Peptides; D017470:Receptors, Glutamate; D001127:Arginine Vasopressin; D010121:Oxytocin; D004763:Glucagon-Like Peptides; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; C051322:glucagon-like peptide 1 (7-37)