The brain stem is necessary for the expression of behavioral reactions to noxious visceral inputs. Neurons in raphe magnus (RM) and the adjacent nucleus reticularis magnocellularis (NRMC) respond to visceral stimuli and can facilitate the behavioral reaction to visceral stimulation. To determine which RM and NRMC cells could play a role in generating the reaction to colorectal distension (CRD),...

Psychological stress-induced hyperthermia is a fundamental autonomic response in mammals. However, the central circuitry underlying this stress response is poorly understood. Here, we sought to identify sympathetic premotor neurons that mediate a hyperthermic response to social defeat stress, a psychological stress model. Intruder rats that were defeated by a dominant resident conspecific exhib...

Recent evidence suggests that neurons in the medullary raphe are critical to the activation of brown adipose tissue (BAT), the major source of nonshivering heat production in the rat. Yet it is unclear which medullary raphe cells participate in cold defense and how participating cells contribute to BAT activation. Therefore, we recorded extracellularly from raphe cells during three thermoregula...

The main function of Nucleus raphe magnus (NRM) is mostly pain mediation. Our previous study has demonstrated that oxytocin (OXT) regulates antinociception through the central nervous system rather than the peripheral organs, and pain stimulation increases OXT concentration in the NRM. The experiment was designed to investigate OXT in the rat NRM effect on pain modulation. The results showed th...

The nucleus paragigantocellularis (PGI) is located in the rostral ventrolateral medulla and has noticeable connections with some other brain nuclei, such as locus ceruleus, nucleus raphe magnus and periaqueductal gray. In rats it is 3 mm in rostrocaudal and 1 mm in mediolateral and 1 mm in the dorsolateral aspect. Anatomically and functionally, PGI has been divided into two subnuclei, retrofaci...

Several lines of evidence have demonstrated a role for the lateral hypothalamus (LH) in an endogenous system of descending inhibition. The present study, in rats lightly anesthetized with pentobarbital, was undertaken to examine systematically the organization in the brain stem of pathways mediating descending inhibition of the nociceptive tail flick (TF) reflex produced by focal electrical sti...

CENTRAL CHEMORECEPTION refers to detection of CO2/pH within the brain and the subsequent reflex effects on breathing. It involves multiple sites within the hindbrain (9, 12, 19) as focal acidification in vivo uniquely at these sites stimulates breathing, indicating detection and chemoreflex initiation. This Viewpoint is not all inclusive but focuses on recent reports of substantial decreases in...

Effects of intravenous administration of picrotoxin (PTX), a GABA(A) receptor antagonist, upon activities of wide dynamic range (WDR) neurons in the lumbar spinal cord were studied in urethane-chloralose anesthetized cats. Intravenous PTX augmented tactile evoked responses of WDR neurons, but reduced nociceptive responses dose-dependently. Spinal transection reversed the suppression of nocicept...