Effect of nose-only inhalation exposure on estrous cycle in female rats

Abstract

Effect of nose-only inhalation exposure on estrous cycle in female rats was examined to obtain basic data for reproductive toxicity study by inhalation exposure. Female rats were exposed to air for 6 hours/day, 7 days/week, for 4 weeks. Estrous cycle was determined for pre-exposure period and during exposure period. As a result, prolonged estrous cycle was observed in half of animals. Estrous cycle in the animals recovered to the pre-exposure level within 2 or 3 weeks. It was considered that restraint stress by nose-only inhalation exposure resulted in the prolonged estrous cycle.