HANDLING AND OR SALINE INJECTIONS ALTER BASAL AND MORPHINE-EVOKED CHANGES IN DOPAMINE METABOLITES IN THE STRIATUM AND NUCLEUS-ACCUMBENS OF RATS/

The effect of IP saline injections on basal dopamine (DA), homovanilli c acid (HVA), and dihydroxyphenylacetic acid (DOPAC), and morphine-evo ked levels of DA, DOPAC, and HVA in the striatum (STR) and nucleus acc umbens (NAC) of female Sprague-Dawley rats was quantified, using in vi vo microdialysis. In the STR, saline injections twice daily over 3 day s, then once on day 4 (2x/day group), resulted in higher basal DOPAC a nd HVA levels compared to unhandled rats (naive group), or rats inject ed with saline once daily for 4 days (1x/day group). DOPAC and HVA wer e greater after IP injection of 30 mg/kg morphine in the saline 2x/day group compared to the saline 1x/day and naive groups. In the NAC, DOP AC was higher after injection of morphine in saline-pretreated rats, c ompared to naive rats. These results suggest that handling and/or IP s aline injections affect basal and morphine-evoked changes in DA metabo lites in the STR, and morphine-evoked DOPAC in the NAC.