Neuroprotective Serotonin 2A Receptor Peptide Significantly Reduced Hippocampal Inflammation in Rats Exposed to Mild Traumatic Brain Injury.

Abstract

Aims: Neuroinflammation complicates traumatic brain injury predisposing to long-lasting neurologic impairment. The aim of the present study was to test whether parenteral administration a small peptide mimic (SN..8) of the receptor- activating- region of the human serotonin 2A receptor (1-, 3- and 5-days) after traumatic brain injury suppresses hippocampal inflammation in the rat compared to a scrambled peptide sequence of the same eight amino acids.

Methods: Adult male Sprague-Dawley rats were exposed to lateral fluid percussion (LFP)-induced, traumatic brain injury (TBI) vs. sham injury. An identical 2 mg/kg concentration of SN..8 vs LD..8 (scrambled peptide) was administered via intraperitoneal route 1-, 3- and 5-days after injury. Two weeks post injury, the bilateral hippocampal, dorsal and ventral brain regions were examined by RT-PCR for altered gene expression. Comparisons were made between TBI vs sham injury; and active vs scrambled peptide treatment.

Results: Two weeks after injury, the novel SN..8 peptide (vs scrambled peptide) significantly reduced (more than 3-fold) CD68 mRNA relative expression in ventral hippocampus in adult male Sprague-Dawley rats subjected to TBI (N=22) (1.65 ± 0.83 vs 5.27 ± 4.1; P=0.012).

Conclusion: These results suggest that the neuroprotective effects of SN..8 peptide may be due in part to its ability to substantially suppress subacute inflammation in the ventral hippocampus.