Increase in intracellular Ca(2+) and calcitonin gene-related peptide release through metabotropic P2Y receptors in rat dorsal root ganglion neurons.
We examined the effects of the activation of metabotropic P2Y receptors on the intracellular Ca(2+) concentration and the release of neuropeptide calcitonin gene-related peptide (CGRP) in isolated adult rat dorsal root ganglion neurons. In small-sized dorsal root ganglion neurons (soma diameter<30 microm) loaded with fura-2, a bath application of ATP (100 microM) evoked an increase in intracellular Ca(2+) concentration, while the removal of extracellular Ca(2+) partly depressed the response to ATP, thus suggesting that the ATP-induced increase in intracellular Ca(2+) concentration is due to both the release of Ca(2+) from intracellular stores and the influx of extracellular Ca(2+). Bath application of uridine 5'-triphosphate (UTP; 100 microM) also caused an increase in intracellular Ca(2+) concentration in small-sized dorsal root ganglion neurons and the P2 receptor antagonists suramin (100 microM) and pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS; 10 microM) virtually abolished the response, indicating that the intracellular Ca(2+) elevation in response to UTP is mediated through metabotropic P2Y receptors. This intracellular Ca(2+) increase was abolished by pretreating the neurons with thapsigargin (100 nM), suggesting that the UTP-induced increase in intracellular Ca(2+) is primarily due to the release of Ca(2+) from endoplasmic reticulum Ca(2+) stores. An enzyme-linked immunosorbent assay showed that an application of UTP (100 microM) significantly stimulated the release of CGRP and that suramin (100 microM) totally abolished the response, suggesting that P2Y receptor-mediated increase in intracellular Ca(2+) is accompanied by CGRP release from dorsal root ganglion neurons. These results suggest that metabotropic P2Y receptors contribute to extracellular ATP-induced increase in intracellular Ca(2+) concentration and subsequent release of neuropeptide CGRP in rat dorsal root ganglion neurons.
Sanada
M
M
Third Department of Medicine, Shiga University of Medical Science, Otsu, Japan.
Yasuda
H
H
Omatsu-Kanbe
M
M
Sango
K
K
Isono
T
T
Matsuura
H
H
Kikkawa
R
R
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D048429:Cell Size; D005110:Extracellular Space / Q000378:metabolism; D005727:Ganglia, Spinal / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018048:Receptors, Purinergic P2 / Q000502:physiology*; D014544:Uridine Triphosphate / Q000378:metabolism
D018048:Receptors, Purinergic P2; D000255:Adenosine Triphosphate; D015740:Calcitonin Gene-Related Peptide; D002118:Calcium; D014544:Uridine Triphosphate