Effects of corticosterone on maternal behaviour
Subtitle: roles of parity, gonadal hormones, and early experience : y Stephanie Lauranne Rees.
Published: 2006
Language: eng
Number of pages: 255
ISBN-13: 9780494159354
Description: 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 purpose of this thesis was to determine the role of corticosterone, an HPA hormone, in the expression of maternal behaviour and whether factors known to independently affect the HPA axis and maternal behaviour, such as parity and maternal separation, will determine the function of corticosterone. In the first series of experiments, the effects of adrenalectomy and corticosterone on maternal behavior in postpartum rats and sensitized and hormonally-primed virgin rats were investigated. After birth, adrenalectomized rats showed less maternal behaviour than non-adrenalectomized rats. Rats given corticosterone showed more maternal behaviour than rats not given corticosterone. After sensitization, adrenalectomized virgin rats showed more maternal behaviour than non-adrenalectomized virgin rats. Also, sensitized rats given corticosterone showed lower levels of maternal behaviour than sensitized rats not given corticosterone, but inconsistently. After hormonal-priming, adrenalectomized rats showed less time over pups on the first test day than non-adrenalectomized rats regardless of corticosterone replacement. Adrenalectomized rats also showed less time over and licking pups than non-adrenalectomized rats once all rats were maternal. Corticosterone replacement partially reversed the effect on time over pups. In the second series of experiments, the effects of maternal separation (being separated from mother and littermates (separated alone: SA), being separated from mother and not littermates (separated as litter: SL), or being left undisturbed (UND) from postnatal days 2 to 14 for 5 hours daily) on adult virgin and juvenile maternal behavior and on basal HPA measures were investigated. In virgin rats, SA rats became maternal more quickly and showed more licking. There was little effect of separation in juvenile rats. Corticosterone levels were negatively related to several maternal behaviors in the juvenile rat. Juvenile rats also showed lower basal corticosterone than virgin rats, although separation had no effect on basal corticosterone in either virgin or juvenile rats. This suggests that while corticosterone affects the expression of maternal behavior, dependent on parity and gonadal hormone status, separation had little effect on maternal behavior and basal corticosterone levels.
Notes: Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 4151.

Thesis (Ph.D.)--University of Toronto, 2006.

Includes bibliographic references.

Electronic version licensed for access by U. of T. users.