Thermosensitive single-unit activity of in vitro hypothalamic slices.
Single-unit activity was recorded in vitro from tissue slices of rat preoptic area-anterior hypothalamus. The thermosensitivity of 139 units was determined by their changes in firing rate in response to changes in slice temperature. Of these neurons, 30% were warm sensitive, 10% were cold sensitive, and 60% were temperature insensitive. These proportions are similar to results obtained in whole-animal studies, indicating that this is a viable preparation. It also suggests that hypothalamic neuronal thermosensitivity is not dependent on peripheral afferent input. All units had low firing rates (less than 10 imp/s) at 37 degrees C, and 83% of the warm-sensitive units were most thermosensitive above 37 degrees C. This supports the concept that afferent input determines the level of firing rate and range of thermosensitivity of warm-sensitive neurons. The cold-sensitive units also displayed maximal thermosensitivity above 37 degrees C, which would be expected if cold-sensitive neurons received inhibitory synaptic input from nearby warm-sensitive neurons.
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001833:Body Temperature Regulation; D007031:Hypothalamus / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D009474:Neurons / Q000502:physiology; D011301:Preoptic Area / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013696:Temperature