Successful production of offspring using cryopreserved sperm via nonsurgical artificial insemination in rats.

In rats, artificial insemination (AI) is surgically performed as a general tool to obtain offspring using cryopreserved spermatozoa. Nonsurgical AI is a more desirable technology because it does not require any surgical procedures. However, there has never been a successful nonsurgical AI since frozen-thawed rat spermatozoa show low motility. We show here for the first time successful nonsurgical AI in rats using oxytocin treatment. Intraperitoneal injection of oxytocin (1/800 IU) immediately before nonsurgical AI significantly increased the number of sperm collected from the oviducts compared with that without oxytocin treatment. Therefore, to obtain pups, oxytocin was intraperitoneally injected into females mated with vasectomized males, and the rats were then used for nonsurgical AI. Seven of the 12 oxytocin-treated rats became pregnant after nonsurgical AI, and 37 pups were obtained. Only one rat (1/13) without oxytocin treatment was pregnant after nonsurgical AI, and only 1 pup was delivered. These results show success for the first time in obtaining offspring using frozen-thawed rat spermatozoa via nonsurgical AI. Our results also suggest the possibility that oxytocin treatment is effective for improvement of nonsurgical AI even in other species.