Afferents to the ventrolateral preoptic nucleus.
Sleep is influenced by diverse factors such as circadian time, affective states, ambient temperature, pain, etc., but pathways mediating these influences are unknown. To identify pathways that may influence sleep, we examined afferents to the ventrolateral preoptic nucleus (VLPO), an area critically implicated in promoting sleep. Injections of the retrograde tracer cholera toxin B subunit (CTB) into the VLPO produced modest numbers of CTB-labeled monoaminergic neurons in the tuberomammillary nucleus, raphe nuclei, and ventrolateral medulla, as well as a few neurons in the locus coeruleus. Immunohistochemistry for monoaminergic markers showed dense innervation of the VLPO by histaminergic, noradrenergic, and serotonergic fibers. Along with previous findings, these results suggest that the VLPO and monoaminergic nuclei may be reciprocally connected. Retrograde and anterograde tracing showed moderate or heavy inputs to the VLPO from hypothalamic regions including the median preoptic nucleus, lateral hypothalamic area, and dorsomedial hypothalamic nucleus (DMH), autonomic regions including the infralimbic cortex and parabrachial nucleus, and limbic regions including the lateral septal nucleus and ventral subiculum. Light to moderate inputs arose from orexin and melanin concentrating hormone neurons, but cholinergic or dopaminergic inputs were extremely sparse. Suprachiasmatic nucleus (SCN) projections to the VLPO were sparse, but the heavy input to the VLPO from the DMH, which receives direct and indirect SCN inputs, could provide an alternate pathway regulating the circadian timing of sleep. These robust pathways suggest candidate mechanisms by which sleep may be influenced by brain systems regulating arousal, autonomic, limbic, and circadian functions.
Chou
Thomas C
TC
Department of Neurology and Program in Neuroscience, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.
Bjorkum
Alvhild A
AA
Gaus
Stephanie E
SE
Lu
Jun
J
Scammell
Thomas E
TE
Saper
Clifford B
CB
D000344:Afferent Pathways / Q000166:cytology* / Q000502:physiology; D000818:Animals; D001143:Arousal / Q000502:physiology; D001370:Axonal Transport / Q000502:physiology; D015306:Biogenic Monoamines / Q000378:metabolism; D001710:Biotin / Q000031:analogs & derivatives*; D001921:Brain / Q000166:cytology; D002452:Cell Count; D002772:Cholera Toxin; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology; D003911:Dextrans; D007026:Hypothalamic Area, Lateral / Q000166:cytology / Q000502:physiology; D007028:Hypothalamic Hormones / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D008543:Melanins / Q000378:metabolism; D009474:Neurons / Q000166:cytology; D009479:Neuropeptides / Q000378:metabolism; D010835:Phytohemagglutinins; D010907:Pituitary Hormones / Q000378:metabolism; D011301:Preoptic Area / Q000166:cytology* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016622:Silver Staining; D012890:Sleep / Q000502:physiology; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
D015306:Biogenic Monoamines; D003911:Dextrans; D007028:Hypothalamic Hormones; D008543:Melanins; D009479:Neuropeptides; D010835:Phytohemagglutinins; D010907:Pituitary Hormones; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; C076397:biotinylated dextran amine; C100156:leukoagglutinins, plants; C019463:melanin-concentrating hormone; D001710:Biotin; D002772:Cholera Toxin; D002795:Choline O-Acetyltransferase