Title: Influence of suckling and of suckling followed by TRH or LH-RH on plasma prolactin, TSH, GH and FSH. Author: Jeppsson S, Nilsson KO, Rannevik G, Wide L. Journal: Acta Endocrinol (Copenh); 1976 Jun; 82(2):246-53. PubMed ID: 818858. Abstract: Ten women were studied during the first post-partum week. Suckling for 20 min induced a marked increase in plasma prolactin, reaching a maximum within 0-25 min after the end of suckling and then returning to pre-suckling levels after 120 min. Suckling induced no changes in plasma thyrotrophin (TSH), growth hormone (GH) or follicle stimulating hormone (FSH). The iv injection of 200 mug of thyrotrophin releasing hormone (TRH) immediately after suckling resulted in an additional increase in plasma prolactin and a rise in TSH. When given 120 min after suckling TRH was followed by increased plasma levels of prolactin and TSH, which for both hormones were of a magnitude comparable to the TRH induced increment seen immediately after suckling. Thus, suckling did not inhibit the effect of TRH on the release of TSH. These studies indicate that TRH is probably not involved in the suckling induced increase in prolactin secretion. The mean plasma FSH level was below the limit of detection before and after suckling. Neither plasma FSH nor prolactin showed any appearant changes following the iv injection of 25 mug of luteinizing hormone releasing hormone (LH-RH), when given immediately after and 120 min after suckling. When given after suckling as indicated above, TRH induced no changes in plasma GH or FSH and similarly LH-RH was without influence on plasma GH and TSH. The influence of suckling and of suckling followed by thyrotropin re leasing hormone (TRH) or luteinizing hormone-releasing hormone (LH-RH) o n plasma prolactin, thyrotropin (TSH), growth hormone (GH) and follicle stimulating hormone (FSH) was studied in 10 humans. Suckling (20 minute s) induced a significant (p less than .005) rise in plasma prolactin in all subjects, reaching a maximum at 20-45 minutes after start of suckling and then returning to presuckling levels after 120 minutes. TSH, GH and FSH levels were not changed by suckling. The injection of 200 mcg TRH immediately after suckling resulted in an additional increase in plasma prolactin and a rise in TSH. The mean absolute increase in TSH was the same whether the TRH test was performed immediately after suckling or at 120 minutes after the end of suckling. FSH levels could not be detected before or after suckling and neither FSH nor prolactin showed any changes following the injection of LH-RH when given immediately after and 120 minutes after suckling. These results indicate that TRH is probably not involved in the suckling induced increase in prolactin secretion and that the specificity of the releasing effects of TRH and LH-RH, respectively, is not changed during the early postpartum period or influenced by suckling.[Abstract] [Full Text] [Related] [New Search]
