Ascorbic acid 2-glucocide reduces micronucleus induction in distant splenic T lymphocytes following head irradiation

Abstract

Purpose: Evidence from in vivo studies suggests there are enhanced radiation effects in abscopal regions after local head gamma ray irradiation. Splenocyte apoptosis and T lymphocyte micronuclei were induced at higher rates than what would be estimated given the dose at a shielded, distant position. In addition, we evaluated the radio-protective effects of ascorbic acid, acting as a radical scavenger on enhanced radiation effects in the shielded spleen following local head irradiation.

Methods and materials: The heads of C3H mice were exposed to gamma-rays (10-20Gy), while the other parts of the body were shielded with a 5cm-thick lead block. The effective dose for the spleen was calculated at 1.0-2.0Gy. Splenocytes were isolated 24h after cranial irradiation and their apoptosis was measured with an Elisa kit (Roche). The induction of T lymphocyte micronuclei was studied using the cytokinesis-block micronucleus assay. The ascorbic acid glucoside, 2-O-alpha-d-glucopyranosyl-l-ascorbic acid (AA-2G), was orally administered to mice 1h before whole body irradiation. The radio protective effects of AA-2G were estimated by comparing the induction of splenocyte damage (by apoptosis) and micronucleus induction.

Results: The splenocyte damage, as measured by the above two methods, was more excessive than what would be expected given exposure to 1.0-2.0Gy of radiation. Our results suggest that the effects were enhanced in a distant, non-irradiated organ after localized irradiation. Plasma ascorbic acid concentrations were increased 8-10x over control. Treatment with ascorbic acid slightly protected mouse splenocytes from the induction of apoptosis by the enhanced effects of radiation in the abscopal region. However, ascorbic acid significantly inhibited micronucleus induction in splenic T lymphocytes following local head irradiation.

Conclusions: Our results suggest that ascorbic acid effectively scavenged radiation-induced radicals and protected against the enhanced effects of radiation in an abscopal region after local head gamma ray irradiation.