title: Different changes in striatal dopamine metabolism induced by nicotine in mice kept at different ambient temperatures. Evidence for partly separate metabolic routes of dopamine derived from separate compartmentations.
abstract: Further information about the nicotine-induced changes in striatal dopamine metabolism in hypothermic mice was searched by measuring the contents of dopamine and its metabolites (3,4-dihydroxyphenylacetic acid, DOPAC; 3-methoxytyramine, 3-MT; and homovanillic acid, HVA) after blocking the synthesis of dopamine by alpha-methyl-p-tyrosine (alpha-MT). This method gave a possibility to study the effect of nicotine on the metabolism of dopamine in two pools (the cytoplasmic "newly-synthesized" dopamine and the granular dopamine). 3 mg/kg of (-)nicotine was given s.c. four times, at 110, 80, 50 and 20 min, and alpha-MT (250 mg/kg i.p.) at 60 min before sacrifice. To prevent the peripheral effects of nicotine all mice were given hexamethonium (10 mg/kg i.p.) at 140 min before sacrifice. Hexamethonium did not alter striatal dopamine metabolism. Experiments were performed at 20-22 degrees C at which temperature nicotine induced hypothermia or at 32-34 degrees C. The alpha-MT-induced proportional decrease of 3-MT content was clearly less than that of dopamine content. On the contrary the alpha-MT treatment decreased the DOPAC content proportionally more than the dopamine content. Thus DOPAC could not be solely formed from the same dopamine pool as 3-MT. These results indicate that 3-MT reflects best the metabolism of the granular dopamine and DOPAC that of the "newly-synthesized" dopamine. In hypothermic mice nicotine administration reduced the alpha-MT-induced depletion of the dopamine content.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D002395:Catecholamines / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008781:Methyltyrosines / Q000494:pharmacology; D051379:Mice; D009538:Nicotine / Q000494:pharmacology*; D013696:Temperature; D019805:alpha-Methyltyrosine
chemical_list: D002395:Catecholamines; D008781:Methyltyrosines; D019805:alpha-Methyltyrosine; D009538:Nicotine; D004298:Dopamine