Antimutagenic properties of selected radioprotective drug mixtures with regard to X-ray-induced reciprocal translocations in mouse spermatogonia

Anticlastogenic effects of a polyvitamin product, 'Pharmavit', on gamma-ray induction of somatic and germ cell chromosome aberrations in the mouse

The polyvitamin product 'Pharmavit' (Pv), comprising vitamins A, D2, B1, B2, B6, C, E, nicotinamide, and calcium pantothene, was tested for anticlastogenic properties against gamma-rays in mice. Pretreatment with Pv consisted of daily administration by gavage for 30 days at dose levels corresponding to clinical recommendations for an adult human, as recalculated in terms of mg/kg. Findings indicated a reduction of chromosome aberrations in bone marrow cells from mice exposed to 3.0 Gy 137Cs gamma-rays; the reduction concerned predominantly fragments of the chromatid type. Furthermore, a reduction factor of 1.6 was obtained for the frequency of reciprocal translocations induced by spermatogonial irradiation in mice exposed to 4.0 Gy gamma-rays. Pretreatment with vitamin C alone, at the dose present in Pv, proved nearly ineffective in protecting from chromosome aberrations in bone marrow cells. Pharmavit is believed to be a promising agent for application to human populations exposed to the carcinogenic and genetic hazards of ionizing radiation.

Dose-effect relationship for X-ray-induced reciprocal translocations in mouse spermatogonia following pretreatment with 3-aminobenzamide

The influence of 3-aminobenzamide (3-AB) pretreatment on the dose-response relationship for radiation-induced reciprocal translocations in mouse spermatogonial stem cells was studied. The results show that at doses of 3-10 Gy of X-rays the frequencies of translocations were higher in 3-AB-pretreated animals as compared to animals that received X-rays only. The 3-AB pretreatment was not effective at dose levels of 1 and 2 Gy. The shape of the dose-effect curve was similar to that obtained without 3-AB pretreatment, i.e., a humped curve, but the initial slope was clearly steeper and the position of the peak was shifted from 7 to 9 Gy. The effects observed can be explained by a 3-AB-mediated sensitization of normally radioresistant stem cells that are at the stage of stimulation to enter the mitotic cycle, thus increasing the population of radiosensitive spermatogonial stem cells.

Genetic effects of combined chemical-X-ray treatments in male mouse germ cells

Several studies have shown that the yield of genetic damage induced by radiation in male mouse germ cells can be modified by chemical treatments. Pre-treatments with radio-protecting agents have given contradictory results but this appears to be largely attributable to the different germ cell stages tested and dependent upon the level of radiation damage induced. Pre-treatments which enhance the yield of genetic damage have been reported although, as yet, no tests have been conducted with radio-sensitizers. Another form of interaction between chemicals and radiation is specifically found with spermatogonial stem cells. Chemicals that kill cells can, by population depletion, substantially and predictably modify the genetic response to subsequent radiation exposure over a period of several days, or even weeks. Enhancement and reduction in the genetic yield can be attained, dependent upon the interval between treatments, with the modification also varying with the type of genetic damage scored. Post-treatment with one chemical has been shown to reduce the genetic response to radiation exposure.