Oxytocin induces penile erection when injected into the ventral tegmental area of male rats: role of nitric oxide and cyclic GMP

Autor:	Fabrizio Sanna, Maria Rosaria Melis, Gian-Luca Ferri, Tiziana Melis, Cristina Cocco, Salvatora Succu, Antonio Argiolas, Antonio Boi
Rok vydání:	2008
Předmět:	Male medicine.medical_specialty Tyrosine 3-Monooxygenase Microdialysis Neurotoxins 8-Bromo Cyclic Adenosine Monophosphate Nitric Oxide Synthase Type I Nitric Oxide Oxytocin Nitric oxide Rats Sprague-Dawley chemistry.chemical_compound Hemoglobins Dopamine omega-Conotoxin GVIA Internal medicine medicine Animals Humans Channel blocker Enzyme Inhibitors Cyclic GMP Nitrites Nitrates Behavior Animal Dose-Response Relationship Drug musculoskeletal neural and ocular physiology General Neuroscience Penile Erection Dopaminergic Ventral Tegmental Area Oxytocin receptor Rats Ventral tegmental area Endocrinology medicine.anatomical_structure nervous system chemistry Hypothalamus Guanylate Cyclase medicine.drug
Zdroj:	The European journal of neuroscience. 28(4)
ISSN:	1460-9568
Popis:	Oxytocin (80 ng) injected into the caudal mesencephalic ventral tegmental area (VTA) of male rats induces penile erection. Such an effect occurs together with an increase in nitric oxide (NO) production, as measured by the augmented concentration of NO(2)(-) and NO(3)(-) found in the dialysate obtained from this brain area by means of intracerebral microdialysis. Both effects are abolished by d(CH(2))(5)Tyr(Me)(2)-Orn(8)-vasotocin (1 microg), an oxytocin receptor antagonist, by S-methyl-l-thiocitrulline acetate (20 microg), a neuronal NO synthase inhibitor, or by omega-conotoxin GVIA (50 ng), a N-type Ca(2+) channel blocker, all injected into the VTA 15 min before oxytocin. In contrast, 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one (40 microg), a guanylate cyclase inhibitor, given into the VTA 15 min before oxytocin, abolishes penile erection, but not the increase in NO production, while haemoglobin (40 microg), a NO scavenger, injected immediately before oxytocin reduces the increase in NO production, but not penile erection. 8-Bromo-cyclic guanosine monophosphate (0.5-10 microg) microinjected into the VTA induces penile erection with an inverted U-shaped dose-response curve; the maximal effective dose being 3 microg. Immunohistochemistry reveals that in the caudal VTA oxytocin-containing axons/fibres (originating from the paraventricular nucleus of the hypothalamus) contact cell bodies of mesolimbic dopaminergic (tyrosine hydroxylase-positive) neurons containing both NO synthase and guanylate cyclase. These results suggest that oxytocin injected into the VTA induces penile erection by activating NO synthase in the cell bodies of mesolimbic dopaminergic neurons. NO in turn activates guanylate cyclase present in these neurons, thereby increasing cyclic GMP concentration.
Databáze:	OpenAIRE
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