Cellular localization of responses to catecholamines in brain tissue

The chapter discusses biochemical responses in an attempt to shed light on functional biochemical target cells with β-adrenoceptors. There are two types of target cells with these receptors. The first type is a glial cell in which cAMP is formed, and the second type is a neuron in which the immediate early genes are activated. These two target cells and their possible relationship are discussed. The extent to which the toxin lowers the β-CAMP response is used as a measure of the extent to which β-receptors have a glial localization. The chapter also describes the cellular localization of immediate early gene responses to β- receptor activation in the brain to see if this agrees with the localization of the β-CAMP response. Immediate early genes (IEGs) are a group of genes that are rapidly activated by various neurotransmitters, hormones, and growth factors. It was found that release of the brain norepinephrine (NE) onto β-receptors by the α₂-blocker, yohimbine (which antagonizes the inhibition of NE release by α₂-agonists), caused cells in many regions of the brain to stain positively for c-fos.