Uudistav käitumine ja glutamaadi tase juttkehas

Abstract

Individual differences in exploratory behavior are influenced by vulnerability to stress and reflect physiological and behavioral differences related to mood disorders. In the present study rats with stable differences in exploratory behavior, either high (HE) or low (LE) were differentiated by using the exploration box test. Previously the same model has been used to show that HE rats do not differ from LE rats in baseline glutamate, but have a proportionally higher increase in striatal extracellular glutamate from baseline glutamate after glutamate transporter inhibition with with L-trans-pyrrolidine-2,4-dicarboxylic acid (PDC) (Koolmeister, 2011). These experiments were performed on middle-aged (9 to 12 months old) rats. The aim of our study was to examine whether there are any differences between younger (3 months old) HE and LE rats in striatal glutamate levels. Using in vivo microdialysis and HPLC we measured striatal glutamate concentration before, during and after perfusion with a physiological solution containing PDC (4mM). We found no significant differences in baseline glutamate between HE and LE rats, there were no between-group differences in the concentration changes compared to baseline glutamate in dialysate glutamate after perfusion with PDC, but compared to LE rats, HE rats had proportionally higher increase in striatal glutamate from baseline glutamate after perfusion with PDC (p=0,0022). This means that although no differences in glutamate turnover in rats with different exploratory levels were found, HE rats are more sensitive to changes in glutamate circulation.