The Effect of Ambient Temperature on the Actions of Tremorine on Body Temperature and on the Concentration of Noradrenaline, Dopamine, 5‐hydroxytryptamine and Acetylcholine in Rat Brain

Tremorine (1 ,4-dipyrrolidino-2-butyne) was first introduced by Everett, Blockus & Shepperd in 1956.Since that time there have been reports of its effects on brain acetylcholine (Pepeu, 1963; Holmstedt & Lundgren, 1965) and brain dopamine (Everett, 1964; Holmstedt & Lundgren, 1965).Reports of its effects on brain 5-hydroxytryptamine (5-HT) and noradrenaline have varied.Friedman, Aylesworth & Friedman (1963) demonstrated a decrease in the amount of noradrenaline in rat brain and an increase in the amount of 5-HT, whereas Whittaker & Walaszek (1964) using the same species could not detect changes in either of these substances.Also Holmstedt & Lundgren (1965) could not detect any change in rat brain noradrenaline, but Everett (1964) reported a significant decrease.Friedman & Everett (1964) suggested that the increase in brain 5-HT could be related to tremorine's hypothermic action.Tremorine reduced the body temperature of rats in doses which induced tremor (Ferrari & Gessa, 1964).It is possible that the different effects reported for tremorine on brain 5-HT are related to different ambient temperature conditions, particularly as no mention of ambient temperature is made in the conflicting reports.The object of this investigation was to study the effect of ambient temperature on the action of tremorine both on body temperature and on the amounts of noradrenaline, dopamine, 5-HT and acetylcholine in rat brain. METHODSMale Wistar rats weighing 200 to 250 g were used in all the experiments.Drug injections were made by the intraperitoneal route, and the animals were placed in the selected ambient temperature immediately after injection. Brain amine estimationWhole brain noradrenaline, dopamine and 5-HT were assayed by a fluorimetric method.A 0.4