Central Serotonin Neurons and Thermoregulation

Abstract

This chapter describes the experiment conducted to study the influence of a cold and a warm environmental temperature on the activity of the monoamine neurons of rat brain and spinal cord. Male Sprague-Dawley rats (150–250 gm bodyweight) were used. α-Propyl-dopacetamide, the methyl ester of p- chlorophenylalanine , and the methyl ester of α-methyltyrosine were used as monoamine synthesis inhibitors. Immediately after injection, the rats were divided in groups, which were placed in rooms at + 3 o , + 23 o , + 30 o and + 40°C respectively. 3, 4 or 24 hours later, the animals were killed by decapitation, the brains and spinal cords removed and analyzed biochemically and histochemically for 5-HT, NE, and dopamine. The central NE and 5-HT neurons of rats kept at + 40°C were found to increase their state of neuronal activity, whereas the 5-HT, but not the catecholamine neurons of rats kept at + 3°C showed a decreased neuronal activity. These results indicate that the central NE and 5-HT neurons participate in thermoregulation.