Epidermal growth factor influenced by opioid peptides in immature rat uterus

The aim of the present experiment was to investigate the effect of [D-Met(2 ),Pro(5)] enkephalinamide (ENK) implantation on the development of the uter us during 8-33 days of age and the involvement of epidermal growth factor ( EGF) in the effect. Administration of ENK was attained by osmotic minipumps (5 mu g/h) implanted intraperitoneally. ENK resulted in a decrease in the EGF content of the uterus, which was already significant after 48 h of the implantation. The DNA content 24 and 48 h after the treatment decreased, no change at 72 h was found, however the protein/DNA ratio on the effect of E NK treatment was significantly decreased at this time in all examined age g roups. High affinity and lower capacity competitive naloxone binding sites were demonstrated in the membrane fraction of the uteri. Seventy-two h afte r ENK treatment the binding capacity of these sites significantly dropped. The present results suggest a novel multiple interaction between estrogen a nd two probably paracrine hormones, EGF and opioid peptide, in the regulati on of growth and development of the uterus. (J. Endocrinol. Invest. 23: 502 -508, 2000) (C) 2000, Editrice Kurtis.