Abstract
1) Temperature-sensitive neurones in the preoptic region of rats anesthetized with urethan were examined for responsiveness to iontophoretically applied monoamines and acetylcholine. Investigation was performed on 55 temperature-sensitive neurones (40 warm and 15 cold cells) and 18 temperature-insensitive ones.
2) 5-hydroxytryptamine had an excitatory effect on 11 out of 22 warm cells and caused a depression of firing rate in 2 out of 8 cold cells.
3) Reduction of activity following noradrenaline administration was observed in 6 out of 20 warm cells, while in the cold cells 3 out of 10 had an increased discharge rate.
4) Acetylcholine produced either a decrease or an increase in activity of warm cells and cold cells, but depression was predominant.
5) About one-third of temperature-sensitive neurones did not respond to any drugs.
6) Interspike interval histograms of spike trains recorded during the thermally steady state of brain showed gamma distribution in most of the responsive cells responding to monoamines and acetylcholine.
