Estradiol, Progesterone, and Prolactin Regulate Maternal Nest‐Building in Rabbits

Abstract

Maternal nest-building in rabbits, expressed across the last third of pregnancy, consists of: digging a burrow, collecting straw and shaping it into a nest inside the burrow, plucking body hair and lining the straw nest with it. The sequential expression of these activities is correlated with specific changes in the plasma concentration of estradiol, progesterone (P), and prolactin (PRL). To further substantiate the participation of these hormones in the control of maternal nest-building we explored in ovariectomized (ovx) New Zealand white rabbits the capacity of several combinations of such hormones to stimulate digging, straw-carrying, and hair-pulling. Does given estradiol benzoate (EB; 5 micrograms/day from days 3 to 21) plus P (2 or 10 mg/day from days 4 to 16) dug into a substrate from the fourth day of the P treatment until withdrawal of this hormone. The intensity of this effect was greater in the group treated with the high dose of P. Straw-carrying and hair-pulling occurred after P withdrawal in a dose-response way. Food intake, which declines in pregnant females shortly before parturition, decreased to the same extent in both groups of ovx EB-treated does after P withdrawal. A significant increase in PRL plasma levels was observed on day 9 in does given EB plus 2 mg P/day and at two days following P withdrawal in does given EB plus 10 mg P/day. When such ovx EB/P-treated does were given bromocriptine to block PRL release (1 or 3 mg/Kg/day, from days 11 to 21) the expression of digging was unmodified. By contrast, bromocriptine abolished the display of straw-carrying and hair-pulling, and also prevented the decline in food intake normally following P withdrawal. The addition of ovine PRL to ovx EB/P-treated does given bromocriptine reduced the expression of digging, did not restore straw-carrying or hair-pulling, and provoked a sharp decline in food intake. The possible mechanisms of interaction between PRL and steroid hormones for the regulation of specific aspects of the pregnant doe's physiology and behavior are discussed.

Indomethacin blocks pre-partum nest building behaviour in the pig (Sus scrofa): effects on plasma prostaglandin F metabolite, oxytocin, cortisol and progesterone

“…These results suggest that cortisol is not involved in the regulation of nest building but may be influenced by external factors such as environment. Although there is evidence for progesterone being involved in aspects of nest building regulation in rabbits (González-Mariscal et al 1996) and straw carrying in pigs (Castren et al 1993), the present experiments have not shown any relationship between plasma progesterone and nest building.…”

“…Prolonged high levels of peripheral oestradiol and progesterone increase nest building behaviour in rabbits, and circulating prolactin also exerts an influence (González-Mariscal et al 1996). However, manipulation of peripheral concentrations of neither oestradiol (Burne et al 1999) nor prolactin (Boulton et al 1998) affect nest building in the pig.…”

Comportamiento materno y bienestar de la coneja doméstica y silvestre y su camada

“…Como se observa en la Figura 1.A, la excavación del sustrato se incrementa conforme se avanza en la gestación, es decir, con altas concentraciones de estradiol 17-β y de progesterona y declina hacia final de la misma, cuando disminuyen los niveles de progesterona. Estas variaciones se replican al inyectar a conejas ovariectomizadas benzoato de estradiol 17-β y progesterona (González-Mariscal et al, 1996). El acarreo de paja al interior del nido se observa solamente al declinar la concentración sanguínea de progesterona al final de la gestación o al dejar de administrar esta hormona a conejas ovariectomizadas tratadas con benzoato de estradiol 17-β (Figura 1.B).…”

“…Sin embargo, el brusco incremento en la con-Figura 1. Variaciones en la intensidad de las conductas de excavación (panel A) y de acarreo de paja (panel B) a lo largo de la gestación (González-Mariscal et al 1994) o durante la administración, a conejas ovariectomizadas (ovx), de benzoato de estradiol (días 1-22; 5 µg/día) combinado con 2 ó 10 mg/día de progesterona (P; días 3-16; González-Mariscal et al 1996).…”

“…along gestation (González-Mariscal et al, 1994) or during administration, to ovariectomized does (ovx), of estradiol benzoate (days 1-22; 5 µg/day) combined with 2 or 10 mg/day of progesterone days 3-16;González-Mariscal et al, 1996).…”