Increases in serum concentrations of follicle-stimulating hormone (FSH) during thyrotrophin-releasing hormone (TRH) infusions in normal men

Pituitary hormone response to thyrotropin-releasing hormone in secondary amenorrheic women associated with simple weight loss

OBJECTIVE

To investigate endocrine dysfunction in simple weight loss amenorrhea.

DESIGN

We studied pituitary hormone responses to thyrotropin-releasing hormone (TRH) in 10 women with simple weight loss amenorrhea.

SETTING

Department of Obstetrics and Gynecology, University Hospital, University of Tokushima at Tokushima, Japan.

PATIENTS, PARTICIPANTS

Secondary amenorrheic women associated with simple weight loss who did not have anorexia nervosa.

INTERVENTIONS

Intravenous injection of 500 micrograms of synthetic TRH.

MAIN OUTCOME MEASURE

Serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyrotropin, and prolactin were measured before and 15, 30, and 60 minutes after TRH injection.

RESULTS

In normally menstruating women on day 7 of the cycle TRH did not affect serum LH and FSH levels. In women with simple weight loss amenorrhea, however, TRH raised serum LH and FSH levels significantly (P less than 0.01, respectively). Prolactin response to TRH was significantly (P less than 0.05) lower in women with simple weight loss amenorrhea than in normally menstruating women.

CONCLUSIONS

These results indicate that TRH causes a significant rise in serum LH and FSH and the impaired prolactin response in women with simple weight loss amenorrhea.

The effect of thyrotropin-releasing hormone stimulation on serum levels of gonadotropins in women during the follicular and luteal phases of the menstrual cycle

Thyrotropin-releasing hormone (TRH) can stimulate the secretion of adenohypophyseal thyroid-stimulating hormone and prolactin (PRL). The effect of TRH on gonadotropin secretion has not been well defined. This study investigated the effect of TRH administration on the peripheral levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) during the early follicular and midluteal phases of the menstrual cycle in five ovulatory, euthyroid, and normoprolactinemic women. Two hundred micrograms of TRH were administered intravenously on days 3 to 5 and on days 21 to 23 of the same cycle. LH and FSH were measured prior to and every 30 minutes for 2 hours following TRH injection. Ovulation was confirmed in all cycles by midluteal progesterone. All women had normal thyroid-stimulating hormone (TSH) and PRL responses to TRH stimulation in both cycle phases. Baseline and stimulated gonadotropin levels were analyzed by analysis of variance. Thirty minutes following TRH infusion, follicular and luteal levels of LH (mIU/ml, mean +/- standard error of the mean) significantly increased from 6.0 +/- 0.8 to 8.0 +/- 1.1 (P less than 0.005), and from 4.8 +/- 0.6 to 7.6 +/- 0.7 (P less than 0.005), respectively. Levels of FSH increased during both phases of the cycle, but the elevation was not statistically significant. These results suggest that TRH can stimulate gonadotrope secretion of LH, but not of FSH, in both the follicular and luteal phases of the cycle.

Gonadotrophin and alpha subunit secretion by human 'functionless' pituitary adenomas in cell culture: long term effects of luteinizing hormone releasing hormone and thyrotrophin releasing hormone

The long-term effects of LHRH and TRH on gonadotrophin alpha subunit, FSH and LH secretion by cell cultures of four human chromophobic pituitary tumours have been examined. The tumours derived from one male and three female patients who presented because of visual disturbance but had no evident endocrine symptoms. Subsequent serum hormone analysis showed the FSH to be high in the male but low or normal in the post-menopausal females whereas LH levels were low in all patients. In culture, basal hormone secretion could be maintained for periods up to 63 d. All tumours secreted alpha subunit and FSH, but much lower amounts of LH. Addition of LHRH or TRH for a period of 12 to 41 d showed that alpha subunit, FSH and LH secretion were stimulated by LHRH from one tumour, by LHRH and TRH from two tumours. There was always a rapid decline in the LH secretion. The tumour which secreted FSH predominantly was stimulated by TRH. We conclude that human pituitary 'functionless' adenomas can secrete gonadotrophin alpha subunit and FSH in vitro and that secretion can be stimulated during long term releasing hormone experiments. LH secretion, however, cannot be maintained.

Paradoxical release of LH under TRH dynamic test in patients suffering from "psychogenic" erective sexual impotency: lack of neuroradiological signs for hypophyseal lesions

More than two thirds of the patients suffering from "psychogenic" erective sexual impotency display a paradoxical LH response to the injection of 200 micrograms of TRH. As it is known that similar responses exist in patients with gonadotropic cell adenomas, we undertook a tomographic examination of the sella turcica in 8 such patients. In none of the patients did the results favour the existence of a microadenoma. Though the hypothesis of an infra-radiological microadenoma cannot be excluded, it is highly plausible that the origin of the paradoxical response observed is a functional impairment of the hypothalamo-hypophyso-gonadal regulation.