NMDA Receptors Contribute to Postnatal Developmental Downregulation of Connexin Expressions in the Rat Locus Coeruleus

It has been shown that during postnatal development, gap junctions decrease. This phenomenon overlaps with the major period of chemical synapse formation and increased synaptic activity during postnatal weeks 1–3. In current study, the expression of connexin 36 (Cx36), Cx32, and Cx43 proteins in locus coeruleus (LC) was examined using Western blot analysis in (postnatal day) PND14 and PND28 following blockade of NMDA receptors in rats to evaluate the role of these receptors in the expression of Cxs. MK801, as an NMDA receptor antagonist, was injected subcutaneously from the first day of birth until 14 or 28 days depending on the experimental groups. The control group received a saline injection in the same volume. Expression of Cxs declined in PND28 compared to PND14 in LC neurons. Also, we found that the expression of Cx36, Cx32, and Cx43 augmented in the rats’ LC in PND14 and PND28 following the blockade of NMDA receptors. The present results suggest that the activity of NMDA receptors may contribute to the downregulation of Cx36, Cx32, and Cx43 in LC during postnatal development.