Possible Role of Neurokinin A in the Control of Prolactin Secretion in Rats and Hamsters

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Abstract
The possible role of neurokinin A (NKA) in the control of prolactin secretion was studied in vivo, by injecting anti‐NKA serum to ovariectomized rats treated with estrogens and to proestrous rats and hamsters. Injections of an anti‐NKA serum to ovariectomized rats treated with two doses of 80 μg 17ß‐estradiol 24 h apart, or treated chronically with estradiol implants induced a significant decrease of serum prolactin levels as compared with those of similarly treated rats injected with normal rabbit serum. In proestrous rats, the anti‐NKA serum did not modify the afternoon surge of prolactin or luteinizing hormone, but when the antiserum was injected the day before, on diestrus II, it significantly reduced the prolactin surge during the afternoon of proestrus. As in these results obtained in the rat, injections of anti‐NKA serum to golden hamsters on diestrus II also significantly decreased the prolactin surge in the afternoon of proestrus. These results suggest a possible physiological role of NKA on prolactin secretion, exerting a stimulatory influence on the release of this hormone.