Dendritic ribosomes suggest local protein synthesis during estrous synaptogenesis.

Synapse number and dendritic spine number fluctuate across the estrous cycle in the hippocampal CA1 stratum radiatum. The synaptogenesis phase of estrous is driven by estrogen and may require newly synthesized proteins. Ribosomes synthesize soluble proteins when free in the cytoplasm, and integral membrane or secretory proteins when membrane-associated. Here we report that ribosomal immunoreactivity and the percentage associated with membranes increases locally in dendrites of the CA1 stratum radiatum during estrogen-induced synaptogenesis. These findings are consistent with a role for estrogen in regulating the local synthesis of integral membrane proteins, e.g. receptors, in dendrites for newly developing synapses across the estrous cycle.