Influence of prenatal ethanol exposure on cholinergic development in the rat striatum

The effect of acute and chronic exposure to ethanol on the developing encephalon: a review

OBJECTIVES: to compare the acute and chronic effects of ethanol on the neural development, by analysis of the ontogenetic neural structure of mammals. METHODS: searches were performed in the following electronic databases: MEDLINE, SciElo, PubMed, LILACS, CAPES periodical, and the Open Journal System. The descriptors used were: "chronic ethanol toxicity", "chronic alcohol toxicity", "acute ethanol toxicity", "acute alcohol", "neural ontogenic development", "neuronal migration disturbances", "neural structure". The following inclusion criteria were used: articles published between 2003 and 2007, some classic articles in the field and an important neuropsychology textbook. RESULTS: the analysis of papers revealed that, although several studies of the chronic effects of ethanol exposure on the mammalian nervous system have been conducted, only a few have investigated the acute effects of ethanol on specific days of gestation, and these studies have revealed important disorders relating to the cerebral tissue. CONCLUSIONS: it should be recommended that women refrain from the consumption of ethanol during gestational phase to protect the fetus' health. Furthermore, the acute consumption of ethanol by women nearing the eighth or ninth week of gestation has been shown to be potentially harmful to the nervous tissue of the fetus.

Loss of nicotine-induced effects on locomotor activity in fetal alcohol-exposed rats

Previous evidence from our laboratory showed that systemic injection of nicotine enhanced attention and memory in control rats, but not fetal alcohol-exposed (FAE) rats. The present study examined the effects of nicotine on two measures of locomotor activity in FAE rats. Subjects were 2-month-old male offspring of Sprague-Dawley rats fed a 35% ethanol-derived caloric diet, a pair-fed sucrose diet, or a chow-fed diet during the last 2 weeks of gestation. The two experiments examined the effects of intraperitoneal injection of saline or nicotine (0.25 or 0.75 mg/kg) on rearing in an operant chamber and locomotor activity in an open field for 60 min. The high dose of nicotine produced a decrease in rearing in the first 10-min period, followed by a later increase in rearing in the pair-fed and chow-fed groups, but not the FAE group. Nicotine also produced an elevation of locomotor activity in the open field in only the two control groups. These findings provide additional evidence that FAE rats show less behavioral responsiveness to nicotine.

Fetal alcohol-exposed rats exhibit differential response to cholinergic drugs on a delay-dependent memory task

Fetal alcohol exposure in human and rodents produces a number of cognitive deficits including impairments in learning and memory. Recent evidence in our laboratory has shown that fetal alcohol-exposed (FAE) rats respond differently to systemic administration of cholinergic drugs when tested for vigilance and locomotor activity. The present study examined the effects of muscarinic and nicotinic agonists and antagonists on memory performance in a delayed alternation task. Subjects were male offspring of Sprague-Dawley rats fed a 35% ethanol-derived caloric diet, pair-fed with sucrose, or chow-fed with lab chow during the last 2 weeks of gestation. Rats (3 months old) were food-deprived prior to training in the T-maze. Rats were first trained in the alternation task at no delay for five sessions. Rats were then trained at longer delays (20, 60, 180 s) until all groups showed similar performance for two consecutive sessions. Each animal was then tested following systemic injections of the cholinergic antagonists scopolamine and mecamylamine (60-s delay) and the cholinergic agonists pilocarpine and nicotine (180-s delay). Rats received saline injections on alternate days of testing. The results revealed that FAE rats exhibited no impairments in alternation performance at the no delay and 20-s delay, but showed impairments on both the 60- and 180-s delays during the initial sessions. However, with additional training, FAE rats showed performance similar to that of control groups at these delays. Following both pilocarpine and nicotine injections, control groups, but not the FAE group, showed significant memory enhancement in the alternation task. Following scopolamine injections, the FAE rats showed a significant impairment, while control groups showed a nonsignificant decrease in performance. All three groups showed impairments in the alternation task following administration of mecamylamine compared to saline treatment. These findings suggest that alterations in the cholinergic system in FAE rats may underlie some of the cognitive deficits observed with prenatal alcohol exposure.

Neurotrophic factors BDNF and GDNF protect embryonic chick spinal cord motoneurons from ethanol neurotoxicity in vivo

Maternal consumption of ethanol is widely recognized as a leading cause of mental and physical deficits. Many populations of the central nervous system are affected by the teratogenic effects of ethanol. Neurotrophic factors (NTFs) have been shown to protect against ethanol neurotoxicity in culture, although there have been no demonstrations of such protection in vivo, in specific neuronal populations. Previous studies have demonstrated that ethanol is toxic to developing chick embryo motoneurons when administered from embryonic day 10 (E10) to E15. NTFs such as brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) have been shown to support developing spinal cord motoneurons, and when exogenously applied, decrease naturally occurring cell death, and protect against axotomy. The concurrent delivery of BDNF or GDNF with ethanol to the embryonic chick from E10 to E15 was designed to examine the capacity of these NTFs to provide in vivo neuroprotection for this ethanol-sensitive motoneuron population. Analysis of motoneuron numbers indicated that both BDNF and GDNF provided protection to developing spinal cord motoneurons from ethanol toxicity, restoring motoneuron numbers to control levels. This study represents the first demonstration of in vivo neuroprotection from ethanol toxicity with respect to specific neuronal populations.