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The Journal of Neuroscience, February 14, 2007, 27(7):1616-1630; doi:10.1523/JNEUROSCI.3498-06.2007
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Behavioral/Systems/Cognitive
The Median Preoptic Nucleus Reciprocally Modulates Activity of Arousal-Related and Sleep-Related Neurons in the Perifornical Lateral Hypothalamus
Natalia Suntsova,1,2,4 Ruben Guzman-Marin,1,2 Sunil Kumar,1,3 Md. Noor Alam,1,2 Ronald Szymusiak,1,3 andDennis McGinty1,2 1Research Service, Veterans Affairs Greater Los Angeles Healthcare System, North Hills, California 91343, 2Departments of Psychology and 3Medicine, University of California Los Angeles, Los Angeles, California 90095, and 4A. B. Kogan Research Institute for Neurocybernetics, Rostov State University, Rostov-on-Don 344091, Russia
Correspondence should be addressed to Dennis McGinty, Research Service (151A3), Veterans Affairs Greater Los Angeles, Healthcare System, 16111 Plummer Street, North Hills, CA 91343. Email: dmcginty{at}ucla.edu
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 transynaptic 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.
Key words: perifornical lateral hypothalamus; median preoptic nucleus; electrical stimulation; microdialysis; neuronal activity; sleep–waking cycle
Received March 27, 2006; revised Jan. 8, 2007; accepted Jan. 9, 2007.
Correspondence should be addressed to Dennis McGinty, Research Service (151A3), Veterans Affairs Greater Los Angeles, Healthcare System, 16111 Plummer Street, North Hills, CA 91343. Email: dmcginty{at}ucla.edu
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[Abstract] [Full Text] [PDF]
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