The capsaicin receptor TRPV1 is a nonselective cation channel that is expressed in sensory neurons. In this study, we examined the role of the nonreceptor cellular tyrosine kinase c-Src kinase in the modulation of the rat TRPV1. Capsaicininduced currents in identified colonic dorsal root ganglion neurons were blocked by the c-Src kinase inhibitor PP2 and enhanced by the tyrosine phosphatase inhibitor sodium orthovandate. PP2 also abolished currents in human embryonic kidney-293 cells transfected with rat TRPV1, whereas cotransfection of TRPV1 with v-Src resulted in fivefold increase in capsaicin-induced currents. In cells transfected with dominant-negative c-Src and TRPV1, capsaicin-induced currents were decreased by approximately fourfold. TRPV1 co-immunoprecipitated with Src kinase and was tyrosine phosphorylated. These studies demonstrate that TRPV1 is a potential target for cellular tyrosine kinase-dependent phosphorylation.capsaicin; pp 60 ; cation channel; immunoprecipitation; inflammatory bowel disease; pain THE VANILLOID RECEPTOR, VR1 or TRPV1, is a nonselective cation channel with homology to the transient receptor potential (TRP) family of ion channels. Expression of the TRPV1 channel in nociceptors, and its polymodal nature of activation by heat and protons, define the physiological role of this channel in pain sensation. In addition to the direct activation by capsaicin, which was originally used to characterize and clone the TRPV1 channel, both G-protein-coupled receptors (e.g., bradykinin receptor) and tyrosine kinase receptor (e.g., receptor for nerve growth factor) indirectly modulate the kinetics of the channel through pathways involving release from phosphatidylinositol 4,5-bisphosphate (PIP 2 )-mediated inhibition (5).Phosphorylation/dephosphorylation of ion channels is a major mechanism by which channel function is regulated, under both basal conditions, as well as in response to various ligands. Both protein kinases C and A have been demonstrated to regulate TRPV1 currents (1,4,8,10,14,16,18,22,31). The potential phosphorylation sites for protein kinase C⑀ were recently identified as Ser 502 and Ser 800 on TRPV1 (14). Protein kinase A phosphorylates Ser 116 of TRPV1 under basal conditions, and dephosphorylation appears to be a primary mechanism that initiates desensitization of the channel (4). There is now accumulating evidence that cellular tyrosine kinases may also play a potential role in the regulation of ion channel function. For instance, our laboratory (9, 11) and others (3,13,20,25,26,28) have previously defined a significant role for the cellular tyrosine kinase c-Src kinase in regulation of the L-type calcium channel, both under basal conditions and in response to G-protein-coupled receptors and tyrosine kinase receptors. Src-kinase-mediated regulation of store-operated channels, presumably due to TRP channels, has also been demonstrated in fibroblasts (2, 27). A direct role for Src-mediated regulation of TRPV4, a close homolog of TRPV1, was recently identified by Xu et al. (29). ...

Angina pectoris is cardiac pain that typically is manifested as referred pain to the chest and upper left arm. Atypical pain to describe localization of the perception, generally experienced more by women, is referred to the back, neck, and/or jaw. This article summarizes the neurophysiological and pharmacological mechanisms for referred cardiac pain. Spinal cardiac afferent fibers mediate typical anginal pain via pathways from the spinal cord to the thalamus and ultimately cerebral cortex. Spinal neurotransmission involves substance P, glutamate, and transient receptor potential vanilloid-1 (TRPV1) receptors; release of neurokinins such as nuclear factor kappa b (NF-kb) in the spinal cord can modulate neurotransmission. Vagal cardiac afferent fibers likely mediate atypical anginal pain and contribute to cardiac ischemia without accompanying pain via relays through the nucleus of the solitary tract and the C1-C2 spinal segments. The psychological state of an individual can modulate cardiac nociception via pathways involving the amygdala. Descending pathways originating from nucleus raphe magnus and the pons also can modulate cardiac nociception. Sensory input from other visceral organs can mimic cardiac pain due to convergence of this input with cardiac input onto spinothalamic tract neurons. Reduction of converging nociceptive input from the gallbladder and gastrointestinal tract can diminish cardiac pain. Much work remains to be performed to discern the interactions among complex neural pathways that ultimately produce or do not produce the sensations associated with cardiac pain.

Rats treated chronically with diazepam develop tolerance to diazepam effects and show changes in sensitivity of GABAergic systems. In order to investigate possible molecular mechanisms associated with these changes, we have evaluated the effects of acute and chronic diazepam treatment on levels of mRNA for the alpha 1 and beta 1 subunits of the GABAA receptor. Northern blots were hybridized with 32P-labeled GABA alpha 1 and beta 1 cDNA probes, and resulting bands were quantified by autoradiography and densitometry. Levels of alpha 1 mRNA were significantly decreased in cerebral cortex but not in cerebellum or hippocampus of chronic diazepam-treated rats. Acute diazepam treatment did not change levels of alpha 1 mRNA in any of the brain regions. Levels of beta 1 mRNA were examined by Northern blot analysis and also by solution hybridization analysis using a 32P-labeled riboprobe. Both methods showed that beta 1 mRNA was not significantly changed by chronic diazepam treatment. These results demonstrate a specific change in alpha 1 subunit that is associated with a state of altered GABA sensitivity and provide further support for the regional heterogeneity of chronic diazepam effects.

Immunohistochemical and ligand-binding techniques were used to visualize the neurotransmitter serotonin and one of its receptors, the 5-HT1A subtype, in auditory nuclei of the brainstem. Serotonergic fibers and terminal endings were found in all auditory nuclei extending from the cochlear nucleus to the inferior colliculus, including the superior olivary complex and the nuclei of the lateral lemniscus. The density of the innervation varied between and within each nucleus. All serotonergic cell bodies were located outside the auditory nuclei. The 5-HT1A receptor subtype was found in the cochlear nucleus as well as in the inferior colliculus. With no serotonergic cell bodies present in the auditory nuclei, the present neuroanatomic and neurochemical findings support behavioral and neurophysiologic findings that the serotonergic system may modulate central auditory processing.

Kava extracts produce significant murine anxiolytic-like behavioral changes and sedation that are not mediated through the benzodiazepine binding site on the GABA(A) receptor complex.