Stimulation of retinal pigment epithelial cell growth by neuropeptides in vitro.
OBJECTIVE
The proliferation of many cell types are regulated by cytokines and neuropeptides by autocrine and paracrine mechanisms. Retinal pigment epithelial (RPE) cells are also regulated by cytokines. But RPE cells are very close to the neural retina which has some neuropeptides. The present study was to investigate the effects of neuropeptides on the growth of RPE cells.


METHODS
RPE cells were obtained from the eyes of 11 day old chick embryos and cultured in Dulbecco's modified Eagle's culture medium containing 10% fetal calf serum. The growth of RPE cells was evaluated by [3H]-thymidine uptake.


RESULTS
Substance P, beta-endorphin and calcitonin gene-related peptide markedly stimulated the growth of RPE cells. The effects of methionine-enkephalin, somatostatin and vasoactive intestinal peptide were intermediate. The strongest effects of substance P, beta-endorphin and calcitonin gene-related peptide were observed at 10(-6) to 10(-7) M. The stimulation of RPE cells with beta-endorphin was inhibited by naloxone, suggesting that the stimulation with beta-endorphin is mediated by an opioid receptor. beta-endorphin and substance P induced RPE cell growth stimulating activity. Leucine-enkephalin and neuropeptide Y did not affect the growth of RPE cells.


CONCLUSIONS
These results suggest that neuropeptides play an important role in the regulation of RPE cell growth.
Kishi
H
H
Department of Ophthalmology, Hiroshima Mitsubishi Hospital, 4-6-20 Kannonshinmachi, Nishiku, Hiroshima 733, Japan.
Mishima
H K
HK
Sakamoto
I
I
Yamashita
U
U
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D002642:Chick Embryo; D004744:Enkephalin, Methionine / Q000494:pharmacology; D066298:In Vitro Techniques; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009479:Neuropeptides / Q000494:pharmacology*; D010857:Pigment Epithelium of Eye / Q000166:cytology* / Q000187:drug effects*; D013004:Somatostatin / Q000494:pharmacology; D013373:Substance P / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology; D001615:beta-Endorphin / Q000494:pharmacology
D009292:Narcotic Antagonists; D009479:Neuropeptides; D013373:Substance P; D009270:Naloxone; D014660:Vasoactive Intestinal Peptide; D013004:Somatostatin; D004744:Enkephalin, Methionine; D001615:beta-Endorphin; D015740:Calcitonin Gene-Related Peptide