Retention and distribution of manganese in the mouse brain following acute exposure on postnatal day 0, 7, 14 or 42: an autoradiographic and gamma counting study.

ABSTRACT

The relationship between postnatal age at time of Mn exposure, and the retention and distribution of Mn in the brain of the mouse was studied using gamma counting and autoradiography. A single intraperitoneal dose of Mn2+ (11 micrograms/kg or 25 mg/kg) containing radioactive 54Mn was administered on postnatal day 0, 7, 14 or 42. Animals were then killed at various times post exposure (1-114 days) and retention and distribution determined. Maximum retention of Mn in the brain (calculated as a percentage of administered dose) occurred 43 days following exposure on day 0. For day 7, 14 or 42 the highest Mn retention was 24 h after exposure. Maximum retention was 2.9%, 3.5%, 2.5% or 0.3% respectively, Mn retention after 114 days was 0.4%, 0.3%, 0.3% or 0.04% respectively. For the carrier-added group maximum retention was lower with corresponding figures of 2.5%, 2.4%, 1.1% or 0.2% and retention after 114 days was also lower 0.1%, 0.06%, 0.05% or 0.01%. The autoradiography studies indicated that Mn was located in areas of the brain which had a high perikaryal density at the time of exposure and in the choroid plexus. High and low doses of Mn were similarly distributed and there was little change in distribution with time.