We have developed an in vitro jaw-nerve preparation in Wistar albino rats, suitable for the quantitative study of peripheral sensory mechanisms in the oral region. The mandible on one side was excised together with the inferior alveolar nerve and was kept in a modified Krebs-Henseleit solution saturated with O2/CO2 (95:5) gas mixture. Recordings were made from single afferent fibers in the inferior alveolar nerve in response to mechanical stimulation of various oral sites (oral mucosa, periodontal ligament and tooth pulp) by calibrated von Frey hairs. In the case of tooth pulp stimulation, heat and chemical (bradykinin) stimuli were also used. Stable unitary recordings could be made for up to 5 h which was long enough to record the activities evoked by various stimuli applied to the oral area. This paper will describe the procedure for making this preparation together with some responses of single units in the inferior alveolar nerve to mechanical, thermal and chemical stimulations applied to this preparation.

Animals↗

PubMedDate not supplied

Electroacupuncture suppression of the rat jaw opening response after stimulating the caudal spinal trigeminal nucleus.

Suppressive effects of electroacupuncture on the jaw opening responses evoked by stimulation of two areas (anterior and posterior) within the caudal spinal trigeminal nucleus were investigated using lightly anesthetized rats. Electroacupuncture stimulation markedly suppressed the jaw opening responses evoked by stimulating the posterior area, but suppressed only slightly those evoked by stimulating the anterior area.

Acupuncture Therapy↗

PubMedDate not supplied

Gravity stress elevates the nociceptive threshold level with immunohistochemical changes in the rat brain.

Young Wistar male rats were exposed to 2G hypergravity by continuous centrifugation for 15 minutes. The nociceptive threshold was measured by using the von Frey type filament on the rat skin surfaces after hypergravity exposure. Following the hypergravity exposure, rats were sacrificed with anesthesia, then perfused and fixed for immunohistochemical examination. The 2G hypergravity elevated the nociceptive threshold up to 2-fold and induced analgesic effects on rats that remained for 2 hours after termination of centrifugation. Expression of Fos-immunoreactive proteins was prominently induced by 2G hypergravity in the arcuate nucleus and the paraventricular nucleus of the hypothalamus. The 15-minute flash exposure to 2G hypergravity induced pain suppression in rats, which might be attributed to change of neuronal activity in rat hypothalamus.

Animals↗