Chronic pain models amplify transient receptor potential vanilloid 1 (TRPV1) receptor responses in adult rat spinal dorsal horn.

Chronic pain models amplify transient receptor potential vanilloid 1 (TRPV1) receptor responses in adult rat spinal dorsal horn. Neuropharmacology. 2019 Sep 04;:107753 Authors: Uta D, Yoshimura M, Koga K Abstract Persistent pain is associated with negative affect originating from hypersensitivity and/or allodynia. The spinal cord is a key area for nociception as well as chronic pain processing. Specifically, the dorsal horn neurons in lamina II (substantia gelatinosa: SG) receive nociceptive inputs from primary afferents such as C fibers and/or Aδ fibers. Transient receptor potential vanilloid 1 (TRPV1) is a major receptor to sense heat as well as nociception. TRPV1 are expressed in the periphery and the central axon terminals of C fibers and/or Aδ fibers in the spinal cord. Activating TRPV1 enhances the release of glutamate in the spinal cord from naïve rodents. Here, we studied whether or not chronic pain could alter the response of TRPV1 channels to exogenous, capsaicin through study of synaptic transmission and neural activity in rat SG neurons. Using in vitro whole-cell patch-clamp recording, we found that bath application of capsaicin facilitated both the frequency and amplitude of miniature and spontaneous excitatory postsynaptic currents beyond a nerve injury and a complete Freund's adjuvant injection observed in the naïve group. Strikingly, capsaicin produced larger amplitudes of inward currents in pain models than compa...
Source: Neuropharmacology - Category: Drugs & Pharmacology Authors: Tags: Neuropharmacology Source Type: research