Background: Most studies on immunocastration currently focused on male animals. However, immunization of male animals does not completely inhibit sexual behavior and fertility. This study aimed to compare the immunocastration effect of KISS1 DNA vaccines encoding different lengths of kisspeptins in female rats for effective castration effects on both male and female rats.
Methods: Fifteen female rats were randomly divided into three groups. The rats in T1 group or T2 group was orally given respectively KISS1-54 or KISS1-10 DNA vaccines with fused tPA signal peptide, and the control group (Group C) was orally administered with empty vector vaccine, at a dose of 5 × 109 CFU/rat at weeks 0, 3 and 6 of the study. Blood samples were collected by retroorbital bleeding before primary immunization and at weeks 3 and 9 after primary immunization.
Results: Both KISS1-54 and KISS1-10 DNA vaccines induced the body's humoral immune response, and the anti-kisspeptin antibody titres in the T1 group were significantly higher than that in T2 and C groups (p < 0.05). The rats in T1 group has lower serum kisspeptin and estradiol levels than those in T2 and C groups and smaller litter size of rats than those in the control group after mating (p < 0.05). No significant difference was observed between T2 and C groups. The levels of KISS1 and GPR54 mRNA in the hypothalamus and ovaries of the T1 group were significantly lower than that in control group. However, the levels of KISS1 mRNA in the T2 group were significantly lower than that in the control group only in ovaries (p < 0.05).
Conclusion: The oral KISS1-54 DNA vaccine with fused tPA signal peptide was more effective than that KISS1-10 DNA vaccine in suppressing fertility of female rats.
Keywords: DNA vaccine; Female rats; Fertility; Kisspeptin 10; Kisspeptin 54.
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