title: Neurotransmission of the antidepressant-like effects of the growth hormone-releasing hormone antagonist MZ-4-71.
abstract: MZ-4-71 is an antagonist of growth hormone-releasing hormone (GH-RH) which suppresses the secretion of GH-RH. It has been shown that MZ-4-71 has antidepressive-like effects in a modified forced swimming test (FST) in mice, exerts anxiolytic effects in an elevated plus maze test, improves memory consolidation in passive avoidance learning, and corrects the impairment of memory consolidation caused by β-amyloid 25-35 in mice. However, little is known about the mechanisms of action of MZ-4-71 on brain functions. The involvement of the adrenergic, serotonergic, cholinergic, dopaminergic or GABA-ergic receptors in the antidepressant-like action of MZ-4-71 (1.0 μg/2 μl, intracerebroventricular (i.c.v.)) was studied in a modified mouse forced swimming test (FST). Mice were pretreated with a non-selective α-adrenergic receptor antagonist, phenoxybenzamine, an α1/α2β-adrenergic receptor antagonist prazosin, an α2-adrenergic receptor antagonist, yohimbine, a β-adrenergic receptor antagonist, propranolol, a mixed 5-HT1/5-HT2 serotonergic receptor antagonist methysergide, a non-selective 5-HT2 serotonergic receptor antagonist, cyproheptadine, a non-selective muscarinic acetylcholine receptor antagonist, atropine, a D2, D3, D4 dopamine receptor antagonist, haloperidol or a γ-aminobutyric acid subunit A (GABA-A) receptor antagonist bicuculline. Phenoxybenzamine, prazosin, methysergide, cyproheptadine and atropine prevented the effects of MZ-4-71 on the immobility, the climbing and the swimming times. Yohimbine, propranolol, haloperidol and bicuculline did not change the effects of MZ-4-71. The results demonstrated that the antidepressant-like effects of MZ-4-71 in this modified mouse FST are mediated, at least in part, by the an interaction of the α1-adrenergic, 5-HT1/5-HT2 serotonergic, and muscarinic acetylcholine receptors.
authors.affiliation: Department of Pathophysiology, Faculty of Medicine, University of Szeged, Szeged, Hungary.
authors.forename: M
authors.initials: M
authors.lastname: Tanaka
authors.forename: A V
authors.initials: AV
authors.lastname: Schally
authors.forename: G
authors.initials: G
authors.lastname: Telegdy
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000928:Antidepressive Agents / Q000627:therapeutic use*; D003863:Depression / Q000188:drug therapy*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D013007:Growth Hormone-Releasing Hormone / Q000037:antagonists & inhibitors*; D046353:Immobility Response, Tonic / Q000187:drug effects; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D053580:Muscle Strength / Q000187:drug effects; D018377:Neurotransmitter Agents / Q000378:metabolism* / Q000627:therapeutic use; D017337:Sermorelin / Q000031:analogs & derivatives* / Q000627:therapeutic use; D013550:Swimming / Q000523:psychology
chemical_list: D000928:Antidepressive Agents; C095215:MZ 4-71; D018377:Neurotransmitter Agents; D017337:Sermorelin; D013007:Growth Hormone-Releasing Hormone