title: Involvement of nigral oxytocin in locomotor activity: A behavioral, immunohistochemical and lesion study in male rats.
abstract: Oxytocin is involved in the control of different behaviors, from sexual behavior and food consumption to empathy, social and affective behaviors. An imbalance of central oxytocinergic neurotransmission has been also associated with different mental pathologies, from depression, anxiety and anorexia/bulimia to schizophrenia, autism and drug dependence. This study shows that oxytocin may also play a role in the control of locomotor activity. Accordingly, intraperitoneal oxytocin (0.5-2000μg/kg) reduced locomotor activity of adult male rats. This effect was abolished by d(CH2)5Tyr(Me)(2)-Orn(8)-vasotocin, an oxytocin receptor antagonist, given into the lateral ventricles at the dose of 2μg/rat, which was ineffective on locomotor activity. Oxytocin (50-200ng/site) also reduced and d(CH2)5Tyr(Me)(2)-Orn(8)-vasotocin (2μg/site) increased locomotor activity when injected bilaterally into the substantia nigra, a key area in the control of locomotor activity. Conversely, the destruction of nigral neurons bearing oxytocin receptors by the recently characterized neurotoxin oxytocin-saporin injected into the substantia nigra, increased basal locomotor activity. Since oxytocin-saporin injected into the substantia nigra caused a marked reduction of neurons immunoreactive for tyrosine hydroxylase (e.g., nigrostriatal dopaminergic neurons) and for vesicular glutamate transporters VGluT1, VGluT2 and VGluT3 (e.g., glutamatergic neurons), but not for glutamic acid decarboxylase (e.g., GABAergic neurons), together these findings suggest that oxytocin influences locomotor activity by acting on receptors localized presynaptically in nigral glutamatergic nerve terminals (which control the activity of nigral GABAergic efferent neurons projecting to brain stem nuclei controlling locomotor activity), rather than on receptors localized in the cell bodies/dendrites of nigrostriatal dopaminergic neurons.
authors.affiliation: Department of Biomedical Sciences, Section of Cytomorphology, NEF Laboratory, University of Cagliari, 09042 Monserrato (Cagliari), Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Angioni
authors.affiliation: Department of Biomedical Sciences, Section of Cytomorphology, NEF Laboratory, University of Cagliari, 09042 Monserrato (Cagliari), Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Cocco
authors.affiliation: Department of Biomedical Sciences, Section of Cytomorphology, NEF Laboratory, University of Cagliari, 09042 Monserrato (Cagliari), Italy.
authors.forename: Gian-Luca
authors.initials: GL
authors.lastname: Ferri
authors.affiliation: Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, Neuropsychobiology Laboratory, University of Cagliari, 09042 Monserrato (Cagliari), Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Argiolas
authors.affiliation: Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, Neuropsychobiology Laboratory, University of Cagliari, 09042 Monserrato (Cagliari), Italy.
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Melis
authors.affiliation: Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, Neuropsychobiology Laboratory, University of Cagliari, 09042 Monserrato (Cagliari), Italy. Electronic address: fabrizio.sanna@unica.it.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Sanna
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D003712:Dendrites / Q000378:metabolism / Q000502:physiology; D004298:Dopamine / Q000502:physiology; D059290:Dopaminergic Neurons / Q000378:metabolism / Q000502:physiology; D007150:Immunohistochemistry; D008124:Locomotion / Q000187:drug effects*; D008297:Male; D009474:Neurons / Q000187:drug effects; D010121:Oxytocin / Q000378:metabolism* / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018045:Receptors, Oxytocin / Q000378:metabolism / Q000502:physiology; D013378:Substantia Nigra / Q000378:metabolism* / Q000473:pathology
chemical_list: D018045:Receptors, Oxytocin; D010121:Oxytocin; D004298:Dopamine
keywords: Dopamine; Glutamic acid; Locomotor activity; Oxytocin; Oxytocin-saporin; Substantia nigra