JOURNAL ARTICLE

Vanilloid receptor-1 (TRPV1)-dependent activation of inhibitory neurotransmission in spinal substantia gelatinosa neurons of mouse

Francesco Ferrini, Chiara Salio, Angela Maria Vergnano, Adalberto Merighi
Pain 2007, 129 (1): 195-209
17317009
Inhibitory neurotransmission in spinal cord dorsal horn is mainly mediated by gamma-amino butyric acid (GABA) and glycine. By patch clamp recordings and correlative immunocytochemistry, we studied here the effect of 2 microM capsaicin-induced vanilloid receptor-1 (TRPV1) activation on IPSCs in spinal lamina II neurons from post-natal mice. Specificity was confirmed after pre-incubation with the competitive antagonist SB366791 (10 microM). After a single capsaicin pulse, an intense increase of spontaneous IPSC (sIPSC) frequency was observed in the presence of NBQX 10 microM (62/81 neurons; approximately 76%) or NBQX 10 microM + AP-5 20-100 microM (27/42 neurons; approximately 64%). Only a subpopulation (approximately 40%) of responsive neurons showed a significant amplitude increase. Seventy-two percent of the neurons displayed pure GABA(A) receptor-mediated sIPSCs, whereas the remaining ones showed mixed GABAergic/glycinergic events. After two consecutive capsaicin pulses, frequency rises were very similar, and both significantly higher than controls. When the second pulse was given in the presence of 4 microM L732,138, a selective antagonist of the substance P (SP) preferred receptor NK1, we observed a significant loss in frequency increase (63.90% with NBQX and 52.35% with NBQX + AP-5). TTX (1 microM) largely (approximately 81.5%) blocked the effect of capsaicin. These results show that TRPV1 activation on primary afferent fibers releases SP. The peptide then excites inhibitory neurons in laminae I, III and IV, leading to an increased release of GABA/glycine in lamina II via a parallel alternative pathway to glutamate.

Full Text Links

Find Full Text Links for this Article

Discussion

You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read
17317009
×

Save your favorite articles in one place with a free QxMD account.

×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"