title: The median preoptic nucleus reciprocally modulates activity of arousal-related and sleep-related neurons in the perifornical lateral hypothalamus.
abstract: The perifornical-lateral hypothalamic area (PF/LH) contains neuronal groups playing an important role in control of waking and sleep. Among the brain regions that regulate behavioral states, one of the strongest sources of projections to the PF/LH is the median preoptic nucleus (MnPN) containing a sleep-active neuronal population. To evaluate the role of MnPN afferents in the control of PF/LH neuronal activity, we studied the responses of PF/LH cells to electrical stimulation or local chemical manipulation of the MnPN in freely moving rats. Single-pulse electrical stimulation evoked responses in 79% of recorded PF/LH neurons. No cells were activated antidromically. Direct and indirect transsynaptic effects depended on sleep-wake discharge pattern of PF/LH cells. The majority of arousal-related neurons, that is, cells discharging at maximal rates during active waking (AW) or during AW and rapid eye movement (REM) sleep, exhibited exclusively or initially inhibitory responses to stimulation. Sleep-related neurons, the cells with elevated discharge during non-REM and REM sleep or selectively active in REM sleep, exhibited exclusively or initially excitatory responses. Activation of the MnPN via microdialytic application of L-glutamate or bicuculline resulted in reduced discharge of arousal-related and in excitation of sleep-related PF/LH neurons. Deactivation of the MnPN with muscimol caused opposite effects. The results indicate that the MnPN contains subset(s) of neurons, which exert inhibitory control over arousal-related and excitatory control over sleep-related PF/LH neurons. We hypothesize that MnPN sleep-active neuronal group has both inhibitory and excitatory outputs that participate in the inhibitory control of arousal-promoting PF/LH mechanisms.
authors.affiliation: Research Service, Veterans Affairs Greater Los Angeles Healthcare System, North Hills, California 91343, USA.
authors.forename: Natalia
authors.initials: N
authors.lastname: Suntsova
authors.forename: Ruben
authors.initials: R
authors.lastname: Guzman-Marin
authors.forename: Sunil
authors.initials: S
authors.lastname: Kumar
authors.forename: Md Noor
authors.initials: MN
authors.lastname: Alam
authors.forename: Ronald
authors.initials: R
authors.lastname: Szymusiak
authors.forename: Dennis
authors.initials: D
authors.lastname: McGinty
mesh_terms: D000200:Action Potentials / Q000502:physiology / Q000528:radiation effects; D000704:Analysis of Variance; D000818:Animals; D001143:Arousal / Q000502:physiology*; D001522:Behavior, Animal; D001640:Bicuculline / Q000494:pharmacology; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D004569:Electroencephalography / Q000379:methods; D004576:Electromyography / Q000379:methods; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D007026:Hypothalamic Area, Lateral / Q000166:cytology*; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D009433:Neural Inhibition / Q000502:physiology / Q000528:radiation effects; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D011301:Preoptic Area / Q000502:physiology* / Q000528:radiation effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012890:Sleep / Q000502:physiology*
chemical_list: D018755:GABA Agonists; D018756:GABA Antagonists; D009118:Muscimol; D018698:Glutamic Acid; D001640:Bicuculline