The effects of adrenalectomy and corticosterone replacement on maternal behavior in the postpartum rat.
It is well known that the hypothalamic-pituitary-adrenal (HPA) axis is activated during stress. Recent work suggests it is also implicated in the regulation of "normal" behaviors. The present studies investigated the effects of adrenalectomy and of varying glucocorticoid concentrations on adult maternal behavior in primiparous rats. In two studies, rats in late pregnancy were adrenalectomized or given sham surgeries and were tested for maternal behavior. In the first study, primiparous rats were given 0, 25, 100, 300, or 500 microg/ml of corticosterone in their drinking water. In the second study, primiparous rats were given either control or corticosterone time-release pellets. Blood samples were taken to ensure that rats demonstrated levels of corticosterone in blood that were relative to doses received. In studies one and two, primiparous adrenalectomized rats showed slightly, but significantly, lower levels of some maternal behaviors, including licking and time in nest, than primiparous sham rats. Primiparous rats given higher doses of corticosterone replacement showed higher levels of these maternal behaviors than primiparous rats given lower doses of corticosterone. In conclusion, adrenalectomy decreases, but does not abolish, maternal behavior. Corticosterone replacement reverses these effects. Corticosterone is not necessary for the initiation or maintenance of maternal behavior but plays a role in the modulation of ongoing maternal behavior.
Department of Psychology, University of Toronto at Mississauga, Mississauga, ON, Canada L5L 1C6.
Stephanie L
SL
Rees
Sonia
S
Panesar
Meir
M
Steiner
Alison S
AS
Fleming
D000284:Administration, Oral; D000311:Adrenal Glands / Q000502:physiology*; D000315:Adrenalectomy; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000704:Analysis of Variance; D000818:Animals; D003345:Corticosterone / Q000008:administration & dosage / Q000097:blood / Q000502:physiology*; D003692:Delayed-Action Preparations; D004305:Dose-Response Relationship, Drug; D005260:Female; D008425:Maternal Behavior / Q000502:physiology*; D049590:Postpartum Period / Q000097:blood / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley
D003692:Delayed-Action Preparations; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone