No abstract

Puberty is associated with an increase in gonadotropin secretion as a result of an increase in gonadotropin-releasing hormone (GnRH) secretion. Kisspeptin is considered to play a key role in puberty onset in many mammalian species, including rodents, ruminants and primates. The present study aimed to determine if changes in hypothalamic expression of the KISS1 gene, encoding kisspeptin, are associated with the onset of puberty in pigs. The animals (n=4 in each group) were perfused with 4% paraformaldehyde at 0, 1, 2, 3 and 4 months old, as prepubertal stages, and at 5 months old, as the peripubertal stage, following each blood sampling. KISS1 gene expressions in coronal sections of brains were visualized by in situ hybridization. Plasma luteinizing hormone (LH) was measured by radioimmunoassay. KISS1 mRNA signals were observed in the arcuate nucleus (ARC) at all ages examined without any significant difference in the number of KISS1-expressing cells, indicating that the KISS1 gene is constantly expressed in the ARC throughout pubertal development in pigs. The plasma LH concentration was the highest in 0-month-old piglets and significantly decreased in the 1- and 2 month-old groups (P<0.05), suggesting a developing negative feedback mechanism affecting gonadotropin release during the prepubertal period. Considering the potent stimulating effect of kisspeptin on gonadotropin release in prepubertal pigs, kisspeptin secretion rather than kisspeptin synthesis may be responsible for the onset of puberty in pigs.

The aim of this study was to improve a non-surgical technique for porcine embryo transfer that would be more effective and could be operated as easy as artificial insemination in the pig farm. Embryos were collected surgically from 13 gilts at 5 to 7 days post insemination by flushing uterine horns. A total of 144 embryos were immediately transferred into 11 recipients, 1 sow and 10 gilts, by the transcervical method with 2 types of balloon catheters (FA 361 and FA 1466 catheter, Fujihira Industries, Ltd., Tokyo). The recipient pigs were anesthetized and their heads laid down on the slope fastening their legs securely.After cleaning the external genitalia, the balloon catheter was inserted into the cervix through the vaginal speculum and fixed in the cervical canal by swelling the balloon.stages were morulae to hatched blastocyst, were transferred into the uterine horn through a catheter with a small volume of sterile physiological saline. Nine of 11 recipients (81.8%) got pregnant, while 2 of 9 pregnant pigs had an abortion at early time of gestation. The remaining 7 pigs farrowed a total results showed that the balloon catheter could be used for non-surgical transfer of porcine embryos, but the embryonic survival rate was affected by the type of catheter.