%0 Journal Article
%T The kappa opioid receptor agonist U50,488H did not affect brain-stimulation reward while it elicited conditioned place aversion in mice.
%A Huang P
%A Gentile TA
%A Muschamp JW
%A Liu-Chen LY
%J BMC Res Notes
%V 13
%N 1
%D Aug 2020 14
%M 32799930
暂无%R 10.1186/s13104-020-05227-7
%X <B>OBJECTIVE: </B>Selective kappa opioid receptor (KOR) agonists were shown to produce a dose-dependent depression of brain-stimulation reward (BSR) in the rat intracranial self-stimulation (ICSS) tests. However, limited studies using mice produced less conclusive results. Here the effects of U50,488H were re-examined on BSR in mice with a larger cohort of animals.<BR><B>RESULTS: </B>Forty C57BL/6J male mice were implanted with the electrodes in medial forebrain bundle. About a week after surgery, mice were subject to ICSS training. Only eighteen passed the two-phase procedures, at which point they readily spun the wheels to obtain reinforcing effect of BSR, and were used for the ICSS tests. Compared with saline (s.c.), U50,488H (2 mg/kg, s.c.) did not have effects on the BSR thresholds within 1 h post-treatment, while it decreased the maximum wheel-spinning rates in a time-dependent manner. In contrast, cocaine (5 mg/kg, s.c.) decreased the BSR thresholds time-dependently without affecting the maximum wheel-spinning rates in the same cohort of mice, demonstrating the validity of our mouse ICSS models. For comparison, U50,488H (2 mg/kg, s.c.) induced significant conditioned place aversion (CPA) in a different cohort of mice without surgeries. Thus, ICSS may not be an appropriate test for KOR agonist-induced aversion in mice.