Peripheral inhibin levels during estrous cycle in buffalo (Bubalus bubalis)

Area of Science:

• Reproductive Endocrinology
• Veterinary Science
• Biochemistry

Background:

• Understanding reproductive cycles in Murrah buffalo is crucial for livestock management.
• Hormonal profiles, including inhibin and progesterone, play key roles in estrous cycle regulation.
• Accurate measurement of these hormones requires validated assays.

Purpose of the Study:

• To validate a radioimmunoassay (RIA) for measuring peripheral plasma immunoreactive inhibin (ir-inhibin) in Murrah buffalo.
• To determine the fluctuations of ir-inhibin levels throughout the estrous cycle in these animals.
• To correlate ir-inhibin patterns with plasma progesterone levels and estrus confirmation.

Main Methods:

• A sensitive and specific RIA was developed using 125-I iodinated inhibin as a tracer and an antiserum against dimeric inhibin.
• Peripheral blood samples were collected daily for 30 days from six Murrah buffalo during July.
• Plasma progesterone was measured to confirm cyclic activity and estrus; ir-inhibin levels were subsequently analyzed.

Main Results:

• The validated RIA demonstrated a sensitivity of 16 pg/tube, with non-specific effects compensated by bullock plasma.
• Peripheral plasma ir-inhibin concentrations ranged from 0.40 ± 0.07 to 0.67 ± 0.13 ng/ml during the estrous cycle.
• Ir-inhibin levels increased during the follicular phase, peaking at estrus (0.65 ± 0.01 ng/ml), then declined, with no significant pattern observed during the luteal phase.

Conclusions:

• The validated RIA is suitable for measuring ir-inhibin in Murrah buffalo plasma.
• Ir-inhibin exhibits a distinct fluctuation pattern during the estrous cycle, primarily associated with the follicular phase and estrus.
• While trends were observed, statistical significance for ir-inhibin changes throughout the entire estrous cycle was not achieved in this study.