Ethanol exposure during the third trimester equivalent does not affect GABAA or AMPA receptor-mediated spontaneous synaptic transmission in rat CA3 pyramidal neurons

Prenatal Exposure to Alcohol Induces Functional and Structural Plasticity in Dopamine D1 Receptor-Expressing Neurons of the Dorsomedial Striatum

BACKGROUND

Prenatal alcohol exposure (PAE) is a leading cause of hyperactivity in children. Excitation of dopamine D1 receptor-expressing medium spiny neurons (D1-MSNs) of the dorsomedial striatum (DMS), a brain region that controls voluntary behavior, is known to induce hyperactivity in mice. We therefore hypothesized that PAE-linked hyperactivity was due to persistently altered glutamatergic activity in DMS D1-MSNs.

METHODS

Female Ai14 tdTomato reporter mice were given access to alcohol in an intermittent access, 2-bottle choice paradigm before pregnancy, and following mating with male D1-Cre mice, through the pregnancy period, and until postnatal day (P) 10. Locomotor activity was tested in juvenile (P21) and adult (P133) offspring, and alcohol-conditioned place preference (CPP) was measured in adult offspring. Glutamatergic activity in DMS D1-MSNs of adult PAE and control mice was measured by slice electrophysiology, followed by measurements of dendritic morphology.

RESULTS

Our voluntary maternal alcohol consumption model resulted in increased locomotor activity in juvenile PAE mice, and this hyperactivity was maintained into adulthood. Furthermore, PAE resulted in a higher alcohol-induced CPP in adult offspring. Glutamatergic activity onto DMS D1-MSNs was also enhanced by PAE. Finally, PAE increased dendritic complexity in DMS D1-MSNs in adult offspring.

CONCLUSIONS

Our model of PAE does result in persistent hyperactivity in offspring. In adult PAE offspring, hyperactivity is accompanied by potentiated glutamatergic strength and afferent connectivity in DMS D1-MSNs, an outcome that is also consistent with the observed increase in alcohol preference in PAE offspring. Consequently, a PAE-sensitive circuit, centered within the D1-MSN, may be linked to behavioral outcomes of PAE.

Synaptic targets: Chronic alcohol actions

Alcohol acts on numerous cellular and molecular targets to regulate neuronal communication within the brain. Chronic alcohol exposure and acute withdrawal generate prominent neuroadaptations at synapses, including compensatory effects on the expression, localization and function of synaptic proteins, channels and receptors. The present article reviews the literature describing the synaptic effects of chronic alcohol exposure and their relevance for synaptic transmission in the central nervous system. This review is not meant to be comprehensive, but rather to highlight the effects that have been observed most consistently and that are thought to contribute to the development of alcohol dependence and the negative aspects of withdrawal. Specifically, we will focus on the major excitatory and inhibitory neurotransmitters in the brain, glutamate and GABA, respectively, and how their neuroadaptations after chronic alcohol exposure contributes to alcohol reinforcement, dependence and withdrawal. This article is part of the Special Issue entitled "Alcoholism".