Opposite modulatory effects of substance P on GABA-and 5-HT-activated currents in the same sensory neurons.
- Author:
Wang-Ping HU
1
;
Zhi-Wang LI
;
Li-Qiang RU
;
You-Zhen FAN
Author Information
1. Department of Neurobiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
- Publication Type:Journal Article
- MeSH:
Animals;
Animals, Newborn;
GABA Antagonists;
pharmacology;
Neurons, Afferent;
physiology;
Patch-Clamp Techniques;
Rats;
Rats, Sprague-Dawley;
Serotonin;
physiology;
Serotonin Antagonists;
pharmacology;
Substance P;
pharmacology;
physiology;
Trigeminal Ganglion;
physiology;
gamma-Aminobutyric Acid;
physiology
- From:
Acta Physiologica Sinica
2004;56(6):703-707
- CountryChina
- Language:English
-
Abstract:
The modulation by substance P of gamma-aminobutyric acid (GABA)- and 5-hydroxytryptamine (5-HT)-activated currents (I(GABA) and I(5-HT)) was studied by using patch-clamp technique in rat trigeminal ganglion (TG) neurons. The majority of neurons examined responded to GABA and 5-HT with inward currents in the same cells (63.8%, 30/47). In 22 out of 30 neurons sensitive to both GABA and 5-HT, pretreatment with substance P (SP, 0.01 micromol/L) suppressed I(GABA) by (35.7 +/-6.1)% and enhanced I(5-HT) by (65.2 +/- 8.7)%. GR 82334, a potent and specific antagonist of NK1 tachykinin receptor, reversibly blocked the modulatory effects of SP. The SP modulation on I(GABA) and I(5-HT) was also abolished by intracellular dialysis of GDP-beta-S, a non-hydrolyzable GDP analog, or GF 109203X, a selective protein kinase C inhibitor. These results suggest that SP exerts opposite modulatory actions on GABA(A) receptor and 5-HT3 receptor activity of the same primary sensory neuron via the same intracellular signal transduction pathway.
