Statistical parametric mapping for effects of verapamil on olfactory connections of rat brain in vivo using manganese-enhanced MR imaging

Abstract

Purpose: We investigated the effect of verapamil on the transport of manganese in the olfactory connections of rat brains in vivo using statistical parametric mapping and manganese-enhanced magnetic resonance (MR) imaging. Methods: We divided 12 7-week-old male Sprague-Dawley rats into 2 groups of six and injected 10 μmL of saline into the right nasal cavities of the first group and 10 μmL of ver-apamil (2.5 mg/mL) into the other group. Twenty minutes after the initial injection, we injected 10 μmL of MnCl 2 (1 mol/L) into the right nasal cavities of both groups. We obtained serial T 1-weighted MR images before administering the verapamil or saline and at 0.5, one, 24, 48, and 72 hours and 7 days after administering the MnCl 2, spatially normalized the MR images on the rat brain atlas, and analyzed the data using voxel-based statistical comparison. Results: Statistical parametric maps demonstrated the transport of manganese. Manganese ions created significant enhancement (t-score=36.6) 24 hours after MnCl 2 administration in the group administered saline but not at the same time point in the group receiving verapamil. The extent of significantly enhanced regions peaked at 72 hours in both groups and both sides of the brain. The peak of extent in the right side brain in the group injected with saline was 70.2 mm 3 and in the group with verapamil, 92.4 mm 3. The extents in the left side were 64.0 mm 3 for the group with saline and 53.2 mm 3 for the group with verapamil.Conclusion: We applied statistical parametric mapping using manganese-enhanced MR imaging to demonstrate in vivo the transport of manganese in the olfactory connections of rat brains with and without verapamil and found that verapamil did affect this transport.