Effect of the neurokinin B (Nkb) on the release of pituitary hormones (LH and TSH) in catfish, Clarias batrachus

Recent evidences, demonstrated that neurokinin b (NKB) and NKB receptor system in fish is an important reproductive regulator. However, in case of catfish the information on the NKB system is limited. Therefore, NKB at the doses of 10 μg, 20 μg, and 40 μg /kg body were injected through intracranial route and the responses by the LH and TSH cells in the catfish pituitary were investigated with the help of immunocytochemistry. Treatments with NKB significantly increased LH immunoreactivity in PPD as compared to that in the control group. However, no significant change was noticed in the percent immunoreactive areas, after the administration of antibodies against NKB. The NKB treatment at the dose of lower to higher concentration (10-40 μg /kg body weight) did not affect the TSH cells in pituitary. These results suggest that the NKB in the catfish stimulates the release of LH without affecting TSH cells.