PubMed · 765056
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H Rozenbaum. 1975-02-15. [Ovulation inducers].. https://pubmed.ncbi.nlm.nih.gov/765056/
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The results of seven gonadotropin releasing hormone (GnRH) loading tests are presented with special respect to the changes of melatonin level. The tests were carried out after a withdrawal bleeding triggered by progesterone (100 mg for 5 days) and plasma FSH, LH, prolactin and melatonin level were determined. The initial melatonin values were between 3.9 and 35.7 pg/ml and were in inverse ratio with the basal gonadotropin levels. In the case of reactive hypophyseal response the melatonin level decreased in every case in inverse ratio with the increase of gonadotropins. In one case, after the GnRH administration there was no increase in gonadotropin production and at the same time the melatonin secretion remained unchanged. According to our examinations the melatonin secretion during the GnRH loading test showed a good correlation with the changes of gonadotropins.
An anovulation group with normal basal prolactin level (less than 600 mU/l) was found during GnRH loading tests. After GnRH administration there was a definite increase in prolactin value together with an insufficient hypophyseal response. Bromocriptine treatment was commenced on the 10th day (daily 2.5 mg) before carrying out the GnRH loading tests again. During the repeated tests prolactin levels remained normal, basal FSH and LH values increased and reactive hypophyseal responses occurred. On the basis of the examination a group ("latens hyperprolactinemia") responding with increased prolactin production during GnRH administration was found. This higher prolactin level inhibits gonadotropin release from hypophysis. In these cases ovulation induction with bromocriptine is adviseable in spite of basal prolactin level is normal.
OBJECTIVE: To test the hypothesis that met-enkephalin has a role in human ovulation and that plasma levels may differ between ovulatory and anovulatory ovarian cycles. DESIGN: This is a descriptive study comparing levels of plasma met-enkephalin, gonadotropins, and ovarian steroids in 12 ultrasonically confirmed ovulatory cycles and 12 anovulatory cycles. SETTING: The study took place in the infertility clinic of a large teaching hospital receiving primary and tertiary referrals of both private and public sector patients. PATIENTS: All patients (n = 16) had infertility greater than or equal to 3 years and normal findings on previous investigation including evidence of ovulation. INTERVENTIONS: Ovarian cycles were defined using transabdominal ultrasound scanning. Biochemical analyses were by radioimmunoassay. MAIN OUTCOME MEASURES: The differences between plasma met-enkephalin levels in the two groups of cycles were compared. RESULTS: Met-enkephalin levels are significantly higher in ovulatory cycles with a significant peak in the 2 postovulatory days (Duncan's multiple range test; P less than 0.05). CONCLUSION: Human ovulation is associated with cyclic elevation of plasma met-enkephalin. Further studies are required to elucidate causality.