Chromium picolinate reduces morphine-dependence in rats, while increasing brain serotonin levels

Abstract Chromium is an essential trace element with anti-diabetic and anti-depressant effect; the latter is considered related to chromium properties of increasing brain serotonin. Cr 3+ salts were shown to improve some forced swimming-parameters and to induce rewarding effects, which are additive to those of morphine, but Cr effect on addictive processes has not been tested. Aim The present study aimed to assess chromium picolinate (CrPi) influence on morphine-dependence in rats. Matherial and methods We used five groups of 10 rats. Groups 1 and 2 (controls) received saline, respectively CrPi, 0.01 mg/kg/day, for 10 days. In groups 3, 4 and 5 dependence was induced with progressively-increased morphine doses (from 5 – day 1–90 mg/kg/day – day 10, s.c.). Group 3 received only morphine, while groups 4 and 5 received CrPi, i.p., 10 and respectively 5 μg/kg/day, during the 10 days of dependence induction. On day 11, groups 3, 4, and 5 were administered 90 mg/kg morphine, and, 2 h later, all rats received naloxone, 2 mg/kg s.c., to precipitate withdrawal. We compared withdrawal intensity in group 3 vs. groups 4 and 5, assessing both individual symptoms and Gellert-Holtzman global withdrawal score. Upon rats sacrifice at the end of the experiments, brain serotonin (5HT) in certain areas and serum Cr were assessed. Results Some withdrawal signs were unequally influenced by CrPi: compulsive mastication was reduced by both CrPi doses (p  Conclusions Our study evidenced a slight, but significant reduction of morphine dependence in rats induced by chromium picolinate, accompanied by increased brain serotonin. This might be considered a supplementary evidence for chromium anti-depressant effect and its serotonin-mediated mechanisms.