title: Effects of melatonin on heat production and enzymatic activity in diurnal and in nocturnal rodents.
abstract: 1. Heat production by means of oxygen consumption (Vo2), and enzymatic activity of malate dehydrogenase (MDH), lactate dehydrogenase (LDH), and glucose-6-phosphate dehydrogenase (G6PDH) were studied in diurnal (Rhabdomys pumilio) as well as nocturnal (Praomys natalensis) murids, as a response to melatonin treatment. 2. A significant (P less than 0.001) increase in Vo2 was noticed in melatonin treated mice of both species at ambient temperatures of Ta = 6 degrees C, 25 degrees C, 30 degrees C and 34 degrees C, when compared to sham operated mice. A significant (P less than 0.001) increase was also recorded in body temperature (Tb) at Ta = 6 degrees C and 25 degrees C. 3. Enzymatic activity was significantly higher: P less than 0.001 for MDH and LDH in R. pumilio, P less than 0.05 for LDH, and P less tha 0.01 for MDH in P. natalensis, after melatonin administration when compared to sham operated animals.
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects*; D002940:Circadian Rhythm / Q000187:drug effects*; D004912:Erythrocytes / Q000201:enzymology; D005954:Glucosephosphate Dehydrogenase / Q000097:blood; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008550:Melatonin / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects; D012377:Rodentia; D013045:Species Specificity
chemical_list: D007770:L-Lactate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D008550:Melatonin