Expression of alpha2A adrenoceptors during rat neocortical development

Area of Science:

• Neuroscience
• Developmental Biology

Background:

• Norepinephrine (NE) is implicated in neurotrophic roles during brain development.
• The alpha2A adrenoceptor subtype is expressed during neuronal migration and differentiation.

Purpose of the Study:

• To investigate the temporal and spatial expression of alpha2A adrenoceptors in the developing rat neocortex.
• To determine the functional presence of alpha2 receptors during fetal cortical development.

Main Methods:

• In situ hybridization and receptor autoradiography were used to map alpha2A adrenoceptor mRNA and protein.
• Agonist-stimulated [35S]GTPgammaS autoradiography detected functional alpha2 receptors.

Main Results:

• Alpha2A adrenoceptor mRNA and protein expression significantly increased by embryonic days 19 and 20, respectively.
• Expression was observed in migrating and differentiating neurons within the cortical plate, intermediate, and subventricular zones of the lateral neocortex.
• Functional alpha2 receptors were detected in the deep layers of the lateral neocortex at embryonic day 20.

Conclusions:

• The expression pattern of alpha2A adrenoceptors suggests a role in mediating norepinephrine's neurotrophic effects on migrating and differentiating neurons in the developing neocortex.
• The transient upregulation and lateral neocortical restriction indicate potential intrinsic regulation of alpha2A adrenoceptor expression during fetal development.