Endogenous Prolactins Promote Apoptosis in Hyaloid Vessels From Neonatal Rats

Abstract

Abstract: : Purpose: The hormone prolactin (PRL) can be proteolytically cleaved to 16K–PRL, a fragment that inhibits the proliferation and promotes the apoptosis of endothelial cells. Here we investigated whether PRL can be synthesized in the eye of neonatal rats and promote the apoptosis–mediated regression of hyaloid vessels occuring after birth. Methods: Eyes were screened for the expression of PRL mRNA by reverse transcription–polymerase chain reaction (RT–PCR). The effect of endogenous PRLs upon apoptosis of hyaloid vessels was investigated by the intravitreal injection of neutralizing anti–PRL antibodies and the evaluation of DNA fragmentation in hyaloid tissue by TUNEL and ELISA. Results: The full–length PRL mRNA was detected in eyes from rats at postnatal days 7 to 14 (P7–14). Intravitreal injection at P10 of anti–PRL antibodies capable of neutralizing the actions of PRL and 16K–PRL, but not control antibodies or vehicle, significantly (P<0.01) reduced apoptosis of the hyaloid tissue at P13. Conclusions: PRL can be synthesized in the retina of neonatal rats and can promote the physiological regression of intraocular blood vessels.

Keywords: apoptosis/cell death • neuropeptides • vascular cells