The effects of stimulating locus coeruleus (LC) and nucleus raphe magnus (NRM) on lumbar dorsal horn cells that had been denervated by dorsal rhizotomy were studied. Both LC and NRM stimulation inhibited the responses of dorsal horn cells from the side of the cord with intact dorsal roots. However, when cells from the side of the spinal cord that had had prior rhizotomies were studied, half of ...

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...

Background: The nucleus raphe magnus (NRM) is involved in thermoregulatory processing. There is a correlation between changes in the firing rates of the cells in the NRM and the application of the peripheral thermal stimulus. Introduction: we examined the effect of reversible inactivation and excitation of NRM on mechanisms involved in tail blood flow (TBF) regulation in hypothermia. Methods: H...

The mu, delta, and kappa opioid receptors are the three main types of opioid receptors found in the central nervous system (CNS) and periphery. These receptors and the peptides with which they interact are important in a number of physiological functions, including analgesia, respiration, and hormonal regulation. This study examines the expression of mu, delta, and kappa receptor mRNAs in the r...

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...

Descending projections arising from brainstem serotonergic (5HT) neurons contribute to both facilitatory and inhibitory controls of spinal cord "pain" transmission neurons. Unclear, however, are the brainstem networks that influence the output of these 5HT neurons. To address this question, here we used a novel neuroanatomical tracing method in a transgenic line of mice in which Cre recombinase...

The anatomical substrate and behavioral pharmacology of stimulation-produced analgesia resulting from electrical stimulation of the pontomesencephalic nucleus cuneiformis (NCF) was determined in the present study. Maximum increase in nociceptive tail-flick latencies following NCF stimulation occurred during the first 5 min post stimulation and decreased afterwards. The increased reflex latency ...