Activation of the Oxytocin Receptor Modulates the Expression of Synaptic Adhesion Molecules in a Cell-Specific Manner.

Synaptic cell adhesion molecules, including neurexins and neuroligins, mediate the formation and maintenance of connections between neuronal cells. Although neurexins and neuroligins are known to interact with each other in a calcium-dependent manner and several neuropeptides have been shown to act through G protein-coupled receptors to increase intracellular calcium levels, no studies have examined the role of the neuropeptide oxytocin in association with adhesion molecules. Given that oxytocin receptors are located on presynaptic and postsynaptic membranes and that oxytocin exerts direct effects on neuronal excitability, it could be hypothesized that oxytocin affects the expression of cell surface adhesion molecules. In the present study, we show that incubation in the presence of oxytocin (1 μM, 48 h) exerted cell-specific effects on the levels of neurexin 2α, neurexin 2β, and neuroligin 3. Oxytocin significantly increased the mRNA expression levels of neurexin 2α, neurexin 2β, and neuroligin 3 in SH-SY5Y, U-87MG, and primary cerebellar cells. The effect of inhibiting oxytocin receptors on the expression of neurexin 2β was more dramatic in U-87MG cells than in SH-SY5Y cells. Oxytocin did not exert effects in primary corticohippocampal cells. Additionally, we measured the expression of selected GTPases to determine whether they could mediate the effects of oxytocin. Oxytocin induced a decrease in the mRNA level of Rac1 in U-87MG and primary cerebellar cells and exerted a stimulatory effect on the expression of RhoB at the gene and protein level in SH-SY5Y cells. These results suggest that the regulation of neurexins and neuroligins involves the activation of oxytocin receptors. These effects are likely mediated by the stimulation of RhoB GTPase, at least in certain types of cells.