Ethanol is the most commonly abused drug in adolescents yet we know very little about its actions in adolescent brain. We seek to understand ethanol effects on the activity-dependent maturation and function of the mammalian cerebellar cortex, which is mediated primarily by the excitatory neurotransmitter glutamate. This is important because the cerebellum has critical roles in motor and cognitive functions, and continues to undergo substantial growth in the adolescent. In particular, N-methyl-D-aspartate receptor (NR) composition and function changes, and ethanol is an antagonist of NRs in many brain regions and neuronal types, including cerebellum. As such, ethanol is predicted to influence NRs themselves as well as signaling cascades that lie downstream of NRs, in particular Ca2+ and calmodulin-dependent kinases in the cytosol and nucleus. We will use a rat model and a combination of molecular biological, immunochemical and anatomical techniques, focusing on NRs and CaMKs in the internal granular layer. We hypothesize that chronic use of ethanol beginning in pre-adolescence will irreversibly interfere with the development and function of the glutamatergic mossy fiber-granule neuron synaptic circuitry and signaling molecules. This will be reflected by specific and persistent alterations in NR2A-C subunit mRNAs and immunoreactive proteins, exon selection in NR1, and maturation of the downstream Ca2+-dependent kinases, CaMKK and CaMKIV. We do not predict substantial cell loss in response to ethanol since death is typically observed when ethanol is administered to neonates at postnatal days 4 -6. Rather, ethanol is expected to interfere with synaptic maturation and therefore, information processing in the adolescent cerebellum. We chose the RO3 mechanism of support because this pilot project will serve as a foundation for future studies exploring the functional consequences of ethanol on cerebellar physiology and pathophysiology. These future studies will be designed with substantial input from our collaborators at Upstate Medical and Binghamton Universities who are established experts in the fields of fetal and adolescent alcohol research. Adolescents consume at least one-fourth of alcohol in this country, yet we understand little about ethanol effects in adolescent brain. The cerebellar cortex, which continues to undergo significant growth and synaptic refinement through adolescence is one of the most sensitive targets of ethanol. We will test the hypothesis that ethanol irreversibly interferes with maturation of excitatory neurotransmitter molecules and their downstream effectors using the rat model. Our results will serve as a basis for future functional studies. ? ? ?
