Passive immunization against inhibin raises the plasma concentration of FSH in cycling Murrah buffaloes

The effects of inhibin antisera on the circulatory levels of gonadotrophins, luteinzing hormone (LH) and follicle stimulating hormone (FSH) were studied in 4 cycling Murrah buffaloes in the age group of 3-1/2 to 4 years. Saline (2.5 ml) was injected s/c twice at 12 hr interval on day 16 of the cycle and inhibin antisera dissolved in 2.5 ml saline was administered similarly during the succeeding cycle into these animals. Blood samples were collected at 6 hl interval starting from day 17 of the cycle till the estrus and at 15 min interval for 4 hr on the day of estrus. Mean LH levels measured during the proestrus were low and did not show any significant difference between the treatments. LH levels showed a peak as expected on the day of estrus but did not show ally significant difference between the treatments. Mean FSH levels measured after inhibin antisera administration in buffaloes showed a significant increase (P < 0.01) both in the proestrus and estrus compared to the levels in the saline-treated buffaloes. The results suggest that passive immunization against inhibin preferentially increases FSH levels but no effect was seen on LH levels in cycling Murrah buffaloes.