Modulation of activity of the striatal dopaminergic system during the hibernation cycle.
To evaluate how the activity of a well-established neurotransmitter pathway is modulated by a behavioral state, 3H-spiperone binding sites and dopamine (DA) and DA metabolite concentrations were measured in the striata of ground squirrels in 5 phases of the hibernation cycle. Whereas levels of striatal DA and its deaminated metabolite DOPAC did not change significantly, the concentrations of the O-methylated-deaminated metabolite, homovanillic acid (HVA), decreased in all phases of hibernation relative to euthermia. Striatal 3H-spiperone binding sites declined across the hibernation cycle in parallel with the reduction of HVA concentration; receptor binding affinity was unchanged by arousal state. In conjunction with previously reported findings, these results are consistent with the hypothesis that hibernation is associated with a down-regulation of the postsynaptic D2 receptors secondary to increased extracellular DA concentration and reduced DA degradation.
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D003342:Corpus Striatum / Q000502:physiology*; D004298:Dopamine / Q000502:physiology*; D006605:Hibernation; D006719:Homovanillic Acid / Q000378:metabolism; D007700:Kinetics; D011954:Receptors, Dopamine / Q000378:metabolism; D012589:Sciuridae; D013134:Spiperone / Q000378:metabolism
D011954:Receptors, Dopamine; D015102:3,4-Dihydroxyphenylacetic Acid; D013134:Spiperone; D004298:Dopamine; D006719:Homovanillic Acid