Cytogenetic effects of vaginally administered gossypol in murine bone marrow cells

Housing temperature influences exercise training adaptations in mice

Exercise training is a powerful means to combat metabolic diseases. Mice are extensively used to investigate the benefits of exercise, but mild cold stress induced by ambient housing temperatures may confound translation to humans. Thermoneutral housing is a strategy to make mice more metabolically similar to humans but its effects on exercise adaptations are unknown. Here we show that thermoneutral housing blunts exercise-induced improvements in insulin action in muscle and adipose tissue and reduces the effects of training on energy expenditure, body composition, and muscle and adipose tissue protein expressions. Thus, many reported effects of exercise training in mice are likely secondary to metabolic stress of ambient housing temperature, making it challenging to translate to humans. We conclude that adaptations to exercise training in mice critically depend upon housing temperature. Our findings underscore housing temperature as a critical parameter in the design and interpretation of murine exercise training studies.

Exercise has been shown to be an effective approach to ameliorate metabolic disease in mice housed at ambient temperatures, a condition of mild cold stress to mice. Here the authors show that molecular and metabolic adaptations to exercise are blunted when mice are housed in thermoneutral conditions.

Genetic toxicity studies of gossypol

Gossypol, a polyphenolic compound extracted from cotton plants, shows promise for use as a male contraceptive, as well as a treatment for gynecological disorders, cancer, and certain microbial diseases. Before gossypol can be considered safe for widespread human use, particularly by healthy people of childbearing age, its effect on normal genetic processes should be understood. Characterization of gossypol's genotoxic potential has not been approached systematically, although numerous clinical and laboratory studies have addressed issues relating to genetic effects of gossypol. This review summarizes results of relevant studies and offers recommendations for the emphasis of future efforts to understand gossypol's genotoxicity potential. Evidence suggesting that gossypol has any genotoxic effects in mammals under normal physiologic conditions so far is weak, at best. However, several unresolved issues that are important for establishing long-term genetic safety of gossypol were uncovered by this analysis. These include the need for a better understanding of the significance of weak increases in SCE frequency seen in a number of laboratory exposure studies, and more definitive, comprehensive animal tumor bioassay data.

The effect of the male contraceptive agent gossypol acetic acid on mouse bone marrow cells in vivo: micronuclei and mitotic index

In this work the genotoxic effect of gossypol acetic acid (gossypol) was evaluated by determining the frequency of micronuclei and mitotic index in male mouse bone marrow cells in vivo. Bone marrow cells were collected at 24th hour after the single intraperitoneal (20, 40, and 80 micrograms/g) administration of gossypol. Polychromatic erythrocytes (PCEs) in the bone marrow were then evaluated with respect to micronuclei frequency. The dose-dependent increase in the micronuclei frequency was observed. However, when compared with the control group, the increase was not found to be significant (P > 0.05). Also the mitotic index values were not found to be different from those control values (P > 0.05). The results suggest that gossypol is not a clastogenic and mutagenic agent in mouse bone marrow cells in vivo.

The in vivo micronucleus assay in mammalian bone marrow and peripheral blood. A report of the U.S. Environmental Protection Agency Gene-Tox Program

The protocol recommended for the micronucleus assay in mammalian bone marrow has been revised and simplified. The number of sample times has been reduced to one or two, depending upon the dosing protocol. The minimum number of cells to be scored per treatment group has been increased to 20,000 to increase the ability of the assay to detect a doubling of the control micronucleus frequency. Use of both male and female animals is recommended. Scoring of micronuclei in polychromatic erythrocytes of peripheral blood is included as a variation of the bone marrow assay. Published data on chemicals tested by the micronucleus assay have been reviewed and are summarized.