The role of cortisol in chronic binge alcohol-induced cerebellar injury: Ovine model

Abstract

Women who drink alcohol during pregnancy are at high risk of giving birth to children with neurodevelopmental disorders. Previous reports from our laboratory have shown that third trimester equivalent binge alcohol exposure at a dose of 1.75 g/kg/day results in significant fetal cerebellar Purkinje cell loss in fetal sheep and that both maternal and fetal adrenocorticotropin (ACTH) and cortisol levels are elevated in response to alcohol treatment. In this study, we hypothesized that repeated elevations in cortisol from chronic binge alcohol are responsible at least in part for fetal neuronal deficits. Animals were divided into four treatment groups: normal control, pair-fed saline control, alcohol and cortisol. The magnitude of elevation in cortisol in response to alcohol was mimicked in the cortisol group by infusing pregnant ewes with hydrocortisone for 6 h on each day of the experiment, and administering saline during the first hour in lieu of alcohol. The experiment was conducted on three consecutive days followed by four days without treatment beginning on gestational day (GD) 109 until GD 132. Peak maternal blood alcohol concentration in the alcohol group was 239 ± 7 mg/dl. The fetal brains were collected and processed for stereological cell counting on GD 133. The estimated total number of fetal cerebellar Purkinje cells, the reference volume and the Purkinje cell density were not altered in response to glucocorticoid infusion in the absence of alcohol. These results suggest that glucocorticoids independently during the third trimester equivalent may not produce fetal cerebellar Purkinje cell loss. However, the elevations in cortisol along with other changes induced by alcohol could together lead to brain injury seen in the fetal alcohol spectrum disorders.

Figure 1

Experimental treatment paradigm. Infusions were administered on three consecutive days followed by four days without alcohol beginning on gestational day (GD) 109 and continuing until GD132. Surgery to implant vascular catheters was performed on GD 104. On GD 133, animals were sacrificed and fetal brains were collected.

Figure 2

Fetal growth measures in normal control (NC), saline (SAL), alcohol (ALC) and cortisol (CORT) groups. Fetal whole body weight and body length (crown to rump) were not different among groups. Fetal adrenal weight was not statistically different between groups (p=0.08).

Figure 3

Maternal plasma cortisol levels (from experiment on gestational day 132). The magnitude of elevation in cortisol in response to alcohol was mimicked in the cortisol group by infusing pregnant ewes with hydrocortisone for 6 hours on each day of the experiment. The cortisol and alcohol groups were not significantly different from each other at any time point, but both groups were significantly increased at 120 minutes compared to the saline control group (*). Maternal cortisol levels were not significantly altered in the saline control group at any time point.

Figure 4

Estimated fetal cerebellar Purkinje cell number (× 10⁶) in normal control (NC), saline (SAL), alcohol (ALC) and cortisol (CORT) groups. Alcohol exposure significantly decreased total Purkinje cell number compared to the normal control, saline control, and the cortisol treatment groups (*). No differences were noted between the controls and the cortisol group.

Figure 5

Histological images from each treatment group. A is from the normal control group, B from the saline group, C from the alcohol group, and D from the cortisol group.