부산대학교 도서관

Purpose The dopamine D.sub.2 receptor (D2R) is important in the mediation of addiction. [[.sup.123]I]iodobenzamide (IBZM), a SPECT ligand for the D2R, has been used for in vivo studies of D2R availability in humans, monkeys, and rats. Although mouse models are important in the study of addiction, [[.sup.123]I]IBZM has not been used in mice SPECT studies. This study evaluates the use of [[.sup.123]I]IBZM for measuring D2R availability in mice. Methods Pharmacokinetics of [[.sup.123]I]IBZM in mice were studied with pinhole SPECT imaging after intravenous (i.v.) injection of [[.sup.123]I]IBZM (20, 40, and 70 MBq). In addition, the ability to measure the release of endogenous dopamine after amphetamine administration with [[.sup.123]I]IBZM SPECT was investigated. Thirdly, i.v. administration, the standard route of administration, and intraperitoneal (i.p.) administration of [[.sup.123]I]IBZM were compared. Results Specific binding of [[.sup.123]I]IBZM within the mouse striatum could be clearly visualized with SPECT. Peak specific striatal binding ratios were reached around 90 min post-injection. After amphetamine administration, the specific binding ratios of [[.sup.123]I]IBZM decreased significantly (-27.2% n=6 p=0.046). Intravenous administration of [[.sup.123]I]IBZM led to significantly higher specific binding than i.p. administration of the same dose. However, we found that i.v. administration of a dose of 70 MBq [[.sup.123]I]IBZM might result in acute ethanol intoxication because ethanol is used as a preparative aid for the routine production of [[.sup.123]I]IBZM. Conclusions Imaging of D2R availability and endogenous dopamine release in mice is feasible using [[.sup.123]I]IBZM single pinhole SPECT. Using commercially produced [[.sup.123]I]IBZM, a dose of 40 MBq injected i.v. can be recommended.