Lack of effect of dopaminergic denervation on caudate-putamen hyperthermia or hypothermia induced by drugs and mild stressors.
A number of drugs and psychological stressors induce brain hyperthermia and increase extracellular dopamine in the caudate-putamen. The present study tested whether caudate-putamen hyperthermia produced by such stimuli is dependent on dopaminergic transmission. Rats were infused with 6-hydroxydopamine unilaterally into the medial forebrain bundle, and after a two-week recovery period, removable thermocouples were used to monitor temperature in the depleted and intact caudate-putamen in freely-moving animals. The indirect dopamine agonist d-amphetamine (1 and 2mg/kg s.c.) increased caudate-putamen temperature, whereas a low dose of the direct agonist apomorphine (0.1mg/kg s.c.) reduced it. Gamma-butyrolactone, which strongly inhibits dopamine release at the dose administered (700mg/kg i.p.), initially reduced and then increased caudate-putamen temperature. Brief (5-10min) presentation of mild stressors, including tail pinch, produced a rapid and transient caudate-putamen hyperthermia. Quantitative (125)I-RTI-55 autoradiography in post-mortem tissue revealed a 97-100% loss of binding to dopamine transporters in the lesioned caudate-putamen. Despite this near-total dopamine denervation, neither basal caudate-putamen temperature, nor any of the observed temperature responses to drugs or mild stressors, was altered. We conclude that in the caudate-putamen, endogenous dopamine is unlikely to modulate temperature significantly at a local level.
Marcangione
Caterina
C
Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada H3G 1Y6.
Constantin
Annie
A
Clarke
Paul B S
PB
D000818:Animals; D002421:Caudate Nucleus / Q000187:drug effects / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism*; D018492:Dopamine Antagonists / Q000009:adverse effects; D005334:Fever / Q000139:chemically induced / Q000378:metabolism* / Q000523:psychology; D007035:Hypothermia / Q000139:chemically induced / Q000378:metabolism* / Q000523:psychology; D008297:Male; D016627:Oxidopamine / Q000009:adverse effects; D011699:Putamen / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D013315:Stress, Psychological / Q000378:metabolism* / Q000523:psychology
D018492:Dopamine Antagonists; D016627:Oxidopamine; D004298:Dopamine