Late onset of Syt2a expression at synapses relevant to social behavior

Abstract

As they form, synapses go through various stages of maturation and refinement. These steps are linked to significant changes in synaptic function, potentially resulting in changes in behavior. Here, we examined the distribution of the synaptic vesicle protein Synaptotagmin 2a (Syt2a) during development of the zebrafish nervous system. Syt2a is widely distributed throughout the midbrain and hindbrain early during larval development but very weakly expressed in the forebrain. Later in development, Syt2a expression levels increase, particularly in regions associated with social behavior, and most intriguingly, around the time social behavior becomes apparent. We provide evidence that Syt2a localizes to synapses on socially-relevant neurons in the ventral forebrain, co-localizing with tyrosine hydroxylase, a biosynthetic enzyme in the dopamine pathway. Our results suggest a maturation step for synapses in the forebrain that are spatiotemporally related to social behavior.