Chapter 18 Glutamate receptors and development of the visual cortex: effect of metabotropic agonists on cAMP

Publisher Summary This chapter focuses on the effect of Metabotropic glutamate receptor (mGluR) agonists and antagonists on the Cyclic adenosine monophosphate (cAMP) second messenger system. The cAMP system has been implicated in hippocampal long-term potentiation (LTP) and could therefore also be involved in visual cortex plasticity. The chapter also examines whether either increases or decreases of cAMP driven by mGluR in rat visual cortex are age-dependent. Glutamate receptors are more active in several respects in young animals than in adults. It examines the effect of metabotropic glutamate agonists on rat cortical cAMP during and after the critical period for visual cortex plasticity. Quisqualate produced a substantial increase in CAMP, which was larger during the critical period than in the adult. The increase was not affected by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) or (2 R )-amino-5-phosphonopentanoate (APV), showing that it was not due to the action of quisqualate on ionotropic glutamate receptors. Thus, it is concluded that it is the stimulation and/or potentiation of cAMP production that is significant, rather than the attenuation of forskolin stimulated CAMP. Because this stimulation and/or potentiation are higher during the critical period than in the adult and the cAMP second messenger system has been implicated in hippocampal plasticity, it may also play a role in visual cortex plasticity.