Source and site of action of anti-luteolytic interferon in red deer (Cervus elaphus): possible involvement of extra-ovarian oxytocin secretion in maternal recognition of pregnancy

Six conceptuses were collected from red deer hinds on day 22 after synchron ization of oestrus with intravaginal progesterone-releasing devices (remova l of device = day 0). Within 24 h of culture in vitro, the supernatant from five of six conceptuses showed detectable antiviral activity. Interferon a lpha (IFN-alpha) receptors were identified by immunohistochemistry on the l uminal surface of the endometrium, in the neurohypophysis and paraventricul ar hypothalamus, but not in the ovaries of the hinds from which the concept uses were collected. Another 16 intact hinds were synchronized as above. In jection of 4 mg IFN i.m. twice a day on days 13-15 had no effect on clopros tenol-induced oxytocin secretion on day 15 and did not prevent cloprostenol -induced luteal regression. Sixteen ovariectomized hinds received a protoco l of steroid treatment to mimic ovarian hormone secretion during the normal oestrous cycle. On day 16, hinds showed undulant oxytocin secretion that s howed a degree of temporal association with uterine PGF(2 alpha) release. T reatment with 4 mg IFN-alpha(1)1 twice a day on days 13-16 had no effect on this spontaneous oxytocin secretion, but reduced the magnitude of cloprost enol-induced oxytocin secretion on day 17 (P < 0.05). These results indicat e that red deer conceptuses secrete an anti-luteolytic IFN to which the end ometrium expresses a receptor during early pregnancy. The presence of IFN r eceptors in the hypothalamus and posterior pituitary and the IFN-induced su ppression of extra-ovarian oxytocin secretion provides tentative evidence o f an involvement of the central nervous system in maternal recognition of p regnancy in deer.