Effects of infertility by cabergoline on serum sex hormones and the inter- And intra-sexual social behaviors of female rattus losea

Abstract

Lesser rice-field rat is one of major pests in eastern and southern Asia, causing considerable losses in rice, vegetables, and other crops. The more serious situation was that R. losea has developed high resistance to anticoagulants with repeated and long-term application of anticoagulant rodenticides in southern China. Fertility control is considered as an alternative strategy for management of this pest. Cabergoline can inhibit prolactin (PRL) secretion and was applied in fertility control for animal, however, the physiological and behavioral mechanisms of cabergoline as a sterilant in practice remain little known. This study determined the effects of different doses of cabergoline on the inter- and intra-sexual social behavior and reproduction physiology in adult female lesser rice-field rats, Rattus losea. Results showed that the ovary weight of female rats treated with cabergoline significantly increased at day 24, but there were no notable changes in the uteri regardless dosage and time. PRL in female rats treated by 50 µg/kg cabergoline significantly was decreased by 56% at day 7 compared with the control. However, estradiol (E2) in rats treated with 50 µg/kg cabergoline was higher than that in control group at day 24, and progesterone (P) secretion was not remarkably influenced by cabergoline. Moreover, the duration of investigation toward normal females in the 50 µg/kg groups at day 3 exceeded that of pre-treatment. The females treated by 100µg/kg cabergoline increased the frequency of investigation towards normal females and self-grooming and resting than pretreatment. The duration of female investigation and defense towards normal males was lower in the 50-µg/kg groups at day 7 than the untreated group. Collectively, these data indicated that cabergoline might increase the amiable and sexual motivation behaviors of female R. losea, which implied that female rats sterilized by cabergoline still might keep the capacity of competitive reproductive interference.