title: Vasopressin and oxytocin excite MCH neurons, but not other lateral hypothalamic GABA neurons.
abstract: Neurons that synthesize melanin-concentrating hormone (MCH) colocalize GABA, regulate energy homeostasis, modulate water intake, and influence anxiety, stress, and social interaction. Similarly, vasopressin and oxytocin can influence the same behaviors and states, suggesting that these neuropeptides may exert part of their effect by modulating MCH neurons. Using whole cell recording in MCH-green fluorescent protein (GFP) transgenic mouse hypothalamic brain slices, we found that both vasopressin and oxytocin evoked a substantial excitatory effect. Both peptides reversibly increased spike frequency and depolarized the membrane potential in a concentration-dependent and tetrodotoxin-resistant manner, indicating a direct effect. Substitution of lithium for extracellular sodium, Na(+)/Ca(2+) exchanger blockers KB-R7943 and SN-6, and intracellular calcium chelator BAPTA, all substantially reduced the vasopressin-mediated depolarization, suggesting activation of the Na(+)/Ca(2+) exchanger. Vasopressin reduced input resistance, and the vasopressin-mediated depolarization was attenuated by SKF-96265, suggesting a second mechanism based on opening nonselective cation channels. Neither vasopressin nor oxytocin showed substantial excitatory actions on lateral hypothalamic inhibitory neurons identified in a glutamate decarboxylase 67 (GAD67)-GFP mouse. The primary vasopressin receptor was vasopressin receptor 1a (V1aR), as suggested by the excitation by V1aR agonist [Arg(8)]vasotocin, the selective V1aR agonist [Phe(2)]OVT and by the presence of V1aR mRNA in MCH cells, but not in other nearby GABA cells, as detected with single-cell RT-PCR. Oxytocin receptor mRNA was also detected in MCH neurons. Together, these data suggest that vasopressin or oxytocin exert a minimal effect on most GABA neurons in the lateral hypothalamus but exert a robust excitatory effect on presumptive GABA cells that contain MCH. Thus, some of the central actions of vasopressin and oxytocin may be mediated through MCH cells.
authors.affiliation: Dept. of Neurosurgery, Yale Univ. School of Medicine, New Haven, CT 06520, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yao
authors.forename: Li-Ying
authors.initials: LY
authors.lastname: Fu
authors.forename: Xiaobing
authors.initials: X
authors.lastname: Zhang
authors.forename: Anthony N
authors.initials: AN
authors.lastname: van den Pol
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000819:agonists / Q000494:pharmacology / Q000502:physiology*; D001593:Benzyl Compounds / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D059330:GABAergic Neurons / Q000187:drug effects / Q000502:physiology*; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000502:physiology; D007028:Hypothalamic Hormones / Q000502:physiology*; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology*; D007093:Imidazoles / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects; D008094:Lithium / Q000494:pharmacology; D008543:Melanins / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008822:Mice, Transgenic; D010121:Oxytocin / Q000494:pharmacology / Q000502:physiology*; D010907:Pituitary Hormones / Q000502:physiology*; D018045:Receptors, Oxytocin / Q000502:physiology; D017483:Receptors, Vasopressin / Q000819:agonists / Q000502:physiology; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors / Q000502:physiology; D053778:Thiazolidines / Q000494:pharmacology; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: C101670:2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate; C487681:2-(4-(4-nitrobenzyloxy)benzyl)thiazolidine-4-carboxylic acid ethyl ester; D001593:Benzyl Compounds; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002614:Chelating Agents; D007028:Hypothalamic Hormones; D007093:Imidazoles; D007473:Ion Channels; D008543:Melanins; D010907:Pituitary Hormones; D018045:Receptors, Oxytocin; D017483:Receptors, Vasopressin; D019831:Sodium-Calcium Exchanger; D053778:Thiazolidines; D001127:Arginine Vasopressin; D010121:Oxytocin; D004533:Egtazic Acid; C019463:melanin-concentrating hormone; D008094:Lithium; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; D013890:Thiourea; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid