Effects of PGE(2) on neurons from rat dorsal root ganglia in intact and adjuvant-inflamed rats: role of NGF on PGE(2)-induced depolarization.
The effects of prostaglandin E(2) (PGE(2)) on primary afferent neurons were studied by intracellular recording from small (<30 microm) dorsal root ganglion (DRG) neurons cultured for up to 3 days. PGE(2) (10(-9)-10(-5) M) depolarized 4-10% of neurons cultured with nerve growth factor (NGF) in intact rats. The percentage of neurons depolarized increased in a concentration dependent manner, while the average amplitude of the depolarization did not change with concentration. The threshold to evoke an action potential was decreased by PGE(2) (10(-9)-10(-5) M) with the maximum percentage at 10(-9) M, and this effect was also observed in neurons not depolarized by PGE(2). Whether a neuron was depolarized by PGE(2) was not related with its capsaicin (CAP) sensitivity. In addition, we examined whether NGF influences the PGE(2) response of neurons in adjuvant-inflamed young adult animals. Removal of NGF from culture medium did not change the percentage of neurons depolarized by PGE(2) in intact rats (20 and 18% for neurons cultured without or with NGF for 2-3 days, respectively). Adjuvant induced inflammation increased the percentage of neurons depolarized by PGE(2) to 38%, but this was not reversed by an addition of anti-NGF antibody to the culture medium, suggesting that NGF does not play a substantial role in the increase in sensitivity to be depolarized by PGE(2).
Kasai
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M
Department of Neural Regulation, Division of Regulation of Organ Function, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan. kasai@sci.kagoshima-u.ac.jp
Mizumura
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D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001169:Arthritis, Experimental / Q000139:chemically induced; D001920:Bradykinin / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology; D002478:Cells, Cultured; D015232:Dinoprostone / Q000494:pharmacology*; D005620:Freund's Adjuvant / Q000633:toxicity; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D007249:Inflammation / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D020932:Nerve Growth Factor / Q000502:physiology*; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012684:Sensory Thresholds / Q000502:physiology; D013618:Tachyphylaxis / Q000502:physiology
D005620:Freund's Adjuvant; D020932:Nerve Growth Factor; D015232:Dinoprostone; D002211:Capsaicin; D001920:Bradykinin