title: Circadian rhythms in neurotransmitter receptors in discrete rat brain regions.
abstract: Circadian rhythms were measured in alpha 1-, alpha 2- and beta-adrenergic, acetylcholine muscarinic (ACh), and benzodiazepine (BDZ) receptor binding in small regions of rat brain. Rhythms in alpha 1-receptor binding were measured in olfactory bulb, frontal, cingulate, piriform, parietal, temporal and occipital cortex, hypothalamus, hippocampus, pons-medulla, caudate-putamen and thalamus-septum. No rhythm was found in cerebellum. Rhythms in alpha 2-receptor binding were measured in frontal, parietal and temporal cortex, and pons-medulla. No rhythm was found in cingulate, piriform or occipital cortex, or hypothalamus. Rhythms in binding to beta-receptors were measured in olfactory bulb, piriform, insular, parietal and temporal cortex, hypothalamus and cerebellum. No rhythms were found in frontal, entorhinal, cingulate, or occipital cortex, hippocampus, caudate-putamen, or pons-medulla. Rhythms in ACh receptor binding were measured in olfactory bulb, parietal cortex and caudate-putamen. No rhythms were found in frontal or occipital cortex, nucleus accumbens, hippocampus, thalamus-septum, pons-medulla or cerebellum. Rhythms in BDZ receptor binding were measured in olfactory bulb, olfactory and occipital cortex, olfactory tubercle, nucleus accumbens, amygdala, caudate-putamen, hippocampus and cerebellum. No rhythms were found in parietal cortex, pons-medulla or thalamus-septum. The 24-hr mean binding to receptors varied between 3- and 10-fold, the highest in cortex and the lowest, usually, in cerebellum. The piriform cortex was particularly high in alpha 1- and alpha 2-adrenergic receptors; the nucleus accumbens and caudate, in ACh receptors; and the amygdala, in BDZ receptors. Most adrenergic and ACh receptor rhythms peaked in subjective night (the period when lights were off under L:D conditions), whereas most BDZ receptor rhythms peaked in subjective day (the time lights were on in L:D). Perhaps in the rat, a nocturnal animal, the adrenergic and ACh receptors mediate activity and the functions that accompany it, and the BDZ receptors mediate rest, and with it, sleep.
authors.affiliation: Clinical Neuroscience Branch, NIMH, Bethesda, MD 20892.
authors.forename: M S
authors.initials: MS
authors.lastname: Kafka
authors.forename: M A
authors.initials: MA
authors.lastname: Benedito
authors.forename: J A
authors.initials: JA
authors.lastname: Blendy
authors.forename: N S
authors.initials: NS
authors.lastname: Tokola
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002940:Circadian Rhythm; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D011950:Receptors, Cholinergic; D011963:Receptors, GABA-A; D017981:Receptors, Neurotransmitter