Early postnatal alcohol exposure produced long-term deficits in brain weight, but not the number of neurons in the locus coeruleus

The locus coeruleus (LC), a small nucleus in the pontine tegmentum with clu sters of norepinephrine (NE) containing neurons, projects to more brain reg ions than any other nucleus in the central nervous system. Therefore, any n euroanatomical deficits in the LC may have wide-ranging functional implicat ions. Previous studies have shown that heavy alcohol exposure during develo pment can damage several brain regions receiving extensive innervation from the LC (e.g., cerebellum and olfactory bulb). In this study, we examined t he effects of early alcohol exposure during development on neuronal numbers in the LC of the adult rat. Sprague-Dawley rat pups were reared using arti ficial rearing techniques during the brain growth spurt period (part of the third trimester equivalent). The pups in the alcohol group received 4.5 g/ kg per day in two of their 12 daily feedings from postnatal days (PDs) 4-9. Gastrostomy and suckle control groups were also included. On PD 90, the an imals were sacrificed and their brains were processed for stereological cel l counting. Whole brain weight, the number of neurons in the LC. the volume and neuronal density of the LC were assessed. There was a significant redu ction in whole brain weight of the alcohol group compared with that of the gastrostomy control group, demonstrating a long lasting effect of alcohol o n overall brain growth. Nevertheless, there were no differences in neuronal number, density and volume of the LC between alcohol and gastrostomy group s. Results were discussed in relation to the issues of temporal and regiona l vulnerabilities. (C) 1999 Elsevier Science B.V. All rights reserved.