Handling during pregnancy in the blue fox (Alopex lagopus): the influence on the fetal pituitary-adrenal axis

Previous studies revealed that handling is a stressor for farmed blue foxes . The present study was designed to examine the effects of a 1-min daily ha ndling stress applied to pregnant blue fox vixens on the function of the fe tal pituitary-adrenal system. Plasma concentrations of adrenocorticotropin hormone (ACTH), cortisol, and progesterone, adrenal content of cortisol and progesterone, in vitro adrenal production of these steroids and response t o ACTH, and adrenal weights were measured in control (C; n = 73) and stress ed (8; n = 58) fetuses, The ACTH levels were lower in stressed fetuses than in the controls (C: males, 128.6 +/- 6.1pg/ml; females, 165.9 +/- 6.1 pg/m l; S: males, 122.3 +/- 5.4 pg/ml; females, 145.0 +/- 8.1 pg/ml; P < 0.05). In contrast, increased plasma cortisol concentrations in both sexes were de monstrated in stressed compared with control fetuses (C: males, 9.2 +/- 0.4 ng/ mi; females, 9.2 +/- 0.4 ng/ml; S: males, 11.8 +/- 0.7 ng/ml; females, 13.2 +/- 0.7 ng/ml; P < 0.00001). The same difference was observed in plas ma progesterone concentrations (C: males, 1.54 +/- 0.07 ng/ml; females, 1.4 9 +/- 0.10 ng/ml; S: males, 1.86 +/- 0.11 ng/ml; females, 1.74 +/- 0.10 ng/ ml; P < 0.01). Prenatal stress did not change the baseline adrenal producti on of cortisol but prevented the cortisol response to ACTH in female fetuse s and decreased the progesterone production in both sexes. Additionally, pr enatally stressed fetuses of both sexes had significantly lower adrenal wei ghts than controls (C: males, 9.4 +/- 0.3 mg; females, 9.5 +/- 0.4 mg; S: m ales, 8.1 +/- 0.3 mg; females, 8.2 +/- 0.4 mg; P < 0.001). These results in dicate that prenatal handling stress induces a dysregulation of the pituita ry-adrenal axis in the fetus and suggest that increased plasma glucocortico ids in the stressed dam can cross the placenta and influence the fetal hypo thalamic-pituitary-adrenal axis. (C) 2001 Academic Press.