Alterations in dendritic spine plasticity in the prefrontal cortex induced by social play restrictions in male rats

Rats are social animals, and their learning is closely linked to social interactions. A complete or partial lack of such interactions can lead to behavioral changes and altered neural communication in the prefrontal cortex (PFC). In this study, we investigated the effects of peer play during the post-weaning developmental period in male rats on locomotor behavior in response to a novel environment. We also analyzed the density and morphology of dendritic spines in the PFC using the Golgi-Cox staining method, and assessed neuronal density in the PFC through stereological analysis. Our results revealed that peer-rearing, but not single rearing-whether with an adult or a peer-increased locomotor activity. Regarding dendritic spine neuroplasticity, both single-rearing conditions (adult or peer) and social isolation reduced spine density in layer 3 pyramidal neurons. However, only rats single-reared with an adult showed a reduced proportion of mushroom spines. In layer 5 pyramidal neurons, single rearing with either an adult or a peer led to dendritic spine degeneration, reflected in decreased spine density and a lower proportion of mushroom spines. In contrast, social isolation only reduced the proportion of mushroom spines in this layer. Notably, social isolation did not alter neuronal density in the PFC. These findings suggest that deprivation of social play significantly impacts synaptic architecture and behavior, highlighting the essential role of social interactions in preserving neuronal integrity.