Henderson, J., Coleman, K., Bethea, C. L. 2007. Alterations in the serotonin system of monkeys exhibiting self-injurious behaviors. American Journal of Primatology 69(S1), 40. (30th Meeting of the American Society of Primatologists Scientific Program, Abstract #22)

Self-injurious behavior (SIB) presents a serious problem in laboratory macaques that cannot be socially housed for scientific reasons. Pharmaceutical treatments that alter the serotonin (5HT) system have sometimes proven effective in alleviating SIB in both human patients and macaques. We hypothesized that monkeys exhibiting SIB have altered expression of proteins governing 5HT function. The brains of 20 rhesus macaques, Macaca mulatta, 10 of which had past or present SIB, were collected and processed for Western blotting. Using a 2 (Male, Female) x 2 (Control, SIB) ANOVA [α=0.05] we found animals with SIB had higher tryptophan hydroxylase (TPH) protein levels, lower 5HT2A receptor levels, and lower serotonin transporter (SERT) protein levels. 5HT1A receptor and 5HT2C receptor protein levels were not significantly different between control and SIB groups. However 5HT1Areceptor protein levels significantly negatively correlated with SIB score in the animals exhibiting SIB [α=0.05]. The lower expression of SERT indicates animals with SIB have less 5HT neurotransmission. However the higher expression of TPH, lower expression of the 5HT2A receptor and negatively correlated 5HT1A receptor levels indicate mechanisms acting to increase 5HT transmission. We speculate animals with SIB have reduced 5HT levels and either acute stress or acts of self-biting unsuccessfully attempt to drive 5HT levels. This study was funded by ONPRC Pilot Project Grant GPRC47166 and NIH MH62677 to CL Bethea.