Pup directed maternal licking and grooming (LG) increases with corticosterone (CORT) supplimentation (Rees et al 2004). Increases in LG lead to an attenuation of the adult offspring's HPA response to stress (Liu et aI1997). Similarly, Neonatal increases in glucocorticoids lead, in adulthood, to the same attenuation of the HPA stress response (Catalani et aI1993). We hypothesize that dams exhibiting increased LG will have increased circulating CORT, and this increase will be reflected in their offspring. This thesis characterizes the HPA hormone profile adrenocorticotropic hormone (ACTH), CORT & Corticosterone Binding Globulin (CBG) in High LG (H) and Low LG (L) litters, 5 days postpartum (P4). Furthermore pup plasma CORT levels are determined at (P) 3,4,6,10 & 14. Finally P10 Hand L LG ACTH, CORT & CBG will be assessed after stress. RESULTS: H compared to L LG dams have significantly increased plasma CORT (p=0.03). At P4, H LG offspring have significantly increased plasma CORT (p=0.03) and significantly decreased plasma ACTH (p=0.04) as compared to L LG offspring. Plasma CBG levels are significantly lower in H compared to L LG offspring (p=0.01) at the same age. Across the Stress Hyporesponsive Period (SHRP) H LG offspring had significantly increased plasma CORT (p= 0.00) compared to L LG offspring at P3. Challenged with a stressor at P10, H LG offspring have an exaggerated plasma CORT response (p=0.00). This data suggests increases in plasma CORT in the dams leads to increased CORT in the high offspring, contributing perhaps to a more mature stress response at P10. / Key word abbreviation: (1) CORT - CORTicosterone, (2) ACTH - AdrenoCorticoTropin releasing Hormone, (3) CBG - Corticosteroid Binding Globulin, (4) SHRP - Stress Hypo-Responsive Period, (5) P - Post-natal day, (6) HPA - Hypothalamic-Pituitary-Adrenal, (7) LG - Licking/Grooming, (8) ADX/OVX - ADrenalectomized/OVarectomized.

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