The neuropeptide-12 improves recognition memory and neuronal plasticity of the limbic system in old rats.

ABSTRACT

Aging is a stage of life where cognitive and motor functions are impaired. This is because oxidative and inflammatory processes exacerbate neurodegeneration, which affects dendritic morphology and neuronal communication of limbic regions with memory loss. Recently, the use of trophic substances has been proposed to prevent neuronal deterioration. The neuropeptide-12 (N-PEP-12) has been evaluated in elderly patients with dementia, showing improvements in cognitive tasks due to acts as a neurotrophic factor. In the present work, we evaluated the effect of N-PEP-12 on motor activity and recognition memory, as well as its effects on dendritic morphology and the immunoreactivity of GFAP, Synaptophysin (SYP), and BDNF in neurons of the prefrontal cortex (PFC), dorsal hippocampus (DH) and nucleus accumbens (NAcc) of aged rats. The results show that N-PEP-12 improved the recognition memory, but the motor activity was not modified compared to the control animals. N-PEP-12 increases the density of dendritic spines and the total dendritic length in neurons of the PFC (layers 3 and 5) and in DH (CA1 and CA3). Interestingly NAcc neurons showed a reduction in the number of dendritic spines. In the N-PEP-12 animals, when evaluating the immunoreactivity for SYP and BDNF, there was an increase in the three brain regions, while the mark for GFAP decreased significantly. Our results suggest that N-PEP-12 promotes neuronal plasticity in the limbic system of aged animals, which contributes to improving recognition memory. In this sense, N-PEP-12 can be considered as a pharmacological alternative to prevent or delay brain aging and control senile dementias.