Supraoptic NucleusOxytocinVasopressinsParaventricular Hypothalamic NucleusHypothalamus, AnteriorPituitary Gland, PosteriorHypothalamusMilk EjectionNeuronsNeurosecretory SystemsArginine VasopressinCell NucleusNeurophysinsRats, Sprague-DawleyProto-Oncogene Proteins c-fosWater-Electrolyte BalanceDehydrationSaline Solution, HypertonicOsmotic PressureRats, WistarAction PotentialsReceptors, OxytocinHypertonic SolutionsNaloxoneElectrophysiologyDiuresisLactationPresynaptic TerminalsMicroinjectionsPatch-Clamp TechniquesWater DeprivationImmunohistochemistryDynorphinsOsmosisAutonomic PathwaysHypothalamo-Hypophyseal SystemRats, Inbred StrainsElectric StimulationInjections, IntraventricularNarcotic AntagonistsPreoptic AreaOsmolar ConcentrationCorticotropin-Releasing HormoneReceptors, Opioid, kappaMembrane PotentialsTetraethylammoniumMicrodialysisEvoked PotentialsGABA AntagonistsPregnanoloneSynaptic TransmissionExcitatory Postsynaptic PotentialsNucleus AccumbensTetrodotoxinRats, Long-EvansDrinkingDendritesgamma-Aminobutyric AcidBrainPituitary GlandSodium ChlorideSynapses