Facial thermal input in the caudal trigeminal nucleus of rats reared at 30 degrees C.

Abstract

SUMMARY1. Rats reared from birth in air at 30 'C showed a decreased ability to maintain colonic temperature when exposed to 10 0C as compared with rats reared at 20 'C. This difference was not due to physical factors affecting heat loss, such as surface area or fur thickness.2. In anaesthetized rats extracellular recordings were made in trigeminal nucleus caudalis from higher order neurones with input from facial cold and warm receptors. A systematic search on a grid pattern showed there was no difference between heat-reared and control rats in facial receptive fields or in the abundance, extent and somatotopic distribution of thermal neurones in the nucleus. In both groups almost all the neurones were excited only by facial cooling.3. When single cold neurones were tested quantitatively by the application of controlled temperature changes to their receptive fields on the face there was no difference in the static temperature/discharge rate relationship between the two groups of rats.4. The results suggest that the observed difference in ability to regulate body temperature is not attributable to differences in skin-temperature reception at the level of the trigeminal nucleus.

Sympathetic modulation of cold‐receptive neurones in the trigeminal system of the rat.

“…Extracellular single unit recordings were made using glass-coated, platinum-plated tungsten micro-electrodes which were advanced under visual control using a hydraulic microdrive (Trent Wells). Recordings were made caudal to obex and lateral to the large vein which runs rostrocaudally and delineates the medial extent of the trigeminal nucleus (Dawson, Hellon, Herington & Young, 1982). Correct positioning within the nucleus was confirmed by the distinct neuronal response obtained when stroking the face.…”