Influence of ambient temperature on the thermoregulatory responses to 5-hydroxytryptamine, noradrenaline and acetylcholine injected into the lateral cerebral ventricles of sheep, goats and rabbits

摘要: 1. The influences of ambient temperature (Ta) on the thermoregulatory effector activities and body (Tb) intraventricular injections into sheep, goat rabbit 5-hydroxytryptamine (5-HT), noradrenaline (NA), acetylcholine (ACh), carbachol eserine, have been interpreted in terms a simple neuronal model pathways between thermosensors effectors. 2. In all three species 5-HT minimal doses caused rise respiratory frequency (RF) fall Tb at high Ta, reduction EMG activity low Ta. These effects could be as those an excitatory transmitter acting warm receptor—heat loss pathway. 3. NA RF are inhibitory both sensor—heat cold production pathway. 4. ACh cholinomimetic substances eserine complex more difficult to interpret. small sheep pathway. There was increase At higher dose levels these had reverse which attributed synaptic block due excess substance. 5. injected upon ear consistent with predictions if it is assumed (a) that temperatures direct thermal vessels dominate sympathetic innervation, (b) sensor influence lower peripheral vasomotor tone, it. 6. conclusion reached when consideration given differences thermoneutral possibility reversed levels, 5-HT, control very similar rabbit: heat pathway, pathway has pathways.