Search

The postpartum period is characterized hormonally by elevated levels of PRL and low levels of gonadotropins and sex steroids. In breast feeding, this state of postpartum amenorrhea can persist for an extended period, even though PRL levels decrease slowly. Although the action of PRL on multiple target sites has frequently been suggested as the cause of this ovarian quiescence, a suckling-induced alteration in hypothalamic gonadotropin-releasing hormone (GnRH) production has also been hypothesized. To test this latter hypothesis, we provided a uniform pulsatile GnRH stimulus to eight exclusively breast-feeding women for an 8-week duration beginning at 4 weeks postpartum. Five women with functional hypothalamic amenorrhea served as a comparison group. All women received GnRH administered at a dose of 200 ng/kg every 90 min sc via a portable infusion pump. Serial blood sampling for LH, FSH, and PRL was performed weekly for 5 h at 10-min intervals beginning immediately before initiation of GnRH, during the period of GnRH, and 1 week after the cessation of GnRH. The women collected daily urine aliquots for estrone-3-glucuronide, pregnanediol-3-glucuronide, and LH determinations. Serial transvaginal sonography was used to monitor follicular development. Before GnRH treatment the urinary steroid and serum gonadotropin levels of the two groups were low and similar. As expected, PRL levels were higher in the postpartum women (87 micrograms/mL vs. 4.25 micrograms/L, P < 0.05). After initiation of pulsatile GnRH, LH values increased and FSH values decreased in both groups. The LH increase with GnRH was significantly greater in the breast-feeding group than in the hypothalamic amenorrhea group (19.75 mIU/mL vs. 12.34 mIU/mL, P < 0.05). Analysis of pulse frequency and amplitude revealed a nearly complete 1:1 induction of LH pulses by the exogenous GnRH in both groups, with the breast-feeding group showing a greater amplitude (12.26 mIU/mL vs. 5.34 mIU/mL, P < 0.05). The cycle lengths, urinary steroids, and vaginal ultrasonography demonstrated a more rapid initial ovarian responsiveness in the breast-feeding group, as determined by the length of the first follicular phase. The breast-feeding group also showed a brisker ovarian response, as evidenced by a greater number of follicles that were 12 mm or greater (2.3 vs. 1.2, P < 0.05), and a greater luteal phase peak and integrated pregnanediol excretion, respectively (3.02 micrograms/L creatinine and 39.87 micrograms/L creatinine/cycle vs. 1.89 micrograms/L creatinine and 7.69 micrograms/L creatinine/cycle, P < 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

Human corticotropin-releasing hormone (hCRH) was administered in a pulsatile fashion to eight patients with secondary adrenal insufficiency. These patients were selected on the basis of a normal or exaggerated plasma ACTH response to exogenous ovine CRH, suggesting sparing of the corticotrophs. A continuous 48-h iv infusion of ACTH to restore the adrenal glands to an ACTH-responsive state preceded hCRH administration. Eight 1 microgram/kg bolus injections of hCRH were administered in a 24-h period. The time intervals between hCRH injections were selected to resemble the frequency of spontaneously occurring secretory episodes of plasma ACTH and cortisol. Four of the patients underwent a second study, of identical design, in which normal saline injections were administered instead of hCRH. Pulsatile hCRH treatment resulted in a secretory pattern of ACTH and cortisol similar to that in normal subjects. ACTH and cortisol levels during saline administration were low and had no circadian variation. These findings indicate that exogenous CRH is able to restore normal basal ACTH and cortisol secretory patterns when given in an appropriate manner. It is possible that the pulsatile administration of hCRH may prove to be a more physiological technique for restoring adrenal function of patients with corticotroph-sparing secondary adrenal insufficiency and may avoid some of the complications of glucocorticoid administration.

To study the pathophysiology of hypercortisolism in anorexia nervosa, we measured the cerebrospinal fluid (CSF) levels of corticotropin-releasing hormone (CRH) in patients when they were underweight and at intervals after weight restoration. CSF CRH levels were significantly elevated in hypercortisolemic underweight patients. Both CSF CRH levels and pituitary-adrenal function normalized after weight recovery. A significant positive correlation was found between CSF CRH levels and depression ratings in weight-corrected patients. We conclude that the hypercortisolism of anorexia nervosa reflects a defect at or above the hypothalamus which results in the hypersecretion of endogenous CRH. The positive correlation between CSF CRH and depression in the weight-restored patients is compatible with previous data indicating increased CRH secretion in the depressed phase of primary affective disorder and supports the notion of a relationship between CRH and depressive symptomatology. Moreover, these data are compatible with observations that depression is part of the anorexia nervosa syndrome.

To investigate the effect of endogenous arginine vasopressin (AVP) on ACTH secretion, normal subjects were given infusions of either hypertonic saline (HS) or isotonic saline (NS) combined with human corticotropin-releasing hormone (CRH) or placebo. Basal plasma AVP was 2.3 +/- 0.3 (+/- SE) pg/ml, did not change with NS treatment, and rose to 5.4 +/- 0.6 pg/ml during HS infusion (P less than 0.01). Both basal and CRH-stimulated plasma ACTH and cortisol concentrations increased during HS infusion. Peak plasma ACTH and cortisol levels were 11.4 +/- 1.5 pg/ml and 8.6 +/- 0.8 micrograms/dl, respectively, during the HS (plus placebo) infusion. During the NS (plus placebo) infusion, plasma ACTH and cortisol gradually declined to 6.8 +/- 0.5 pg/ml and 2.6 +/- 0.4 micrograms/dl. The timing of the rise in ACTH during the HS infusion paralleled the rise in AVP. When an iv dose of 1 microgram/kg CRH was administered during the saline infusions, peak plasma ACTH and cortisol levels were 27.7 +/- 6.3 pg/ml and 17.5 +/- 1.0 micrograms/dl, respectively, during the HS infusion and 15.6 +/- 1.7 pg/ml and 13.4 +/- 1.2 micrograms/dl during the NS infusion. When the areas under the hormone response curves were compared, CRH stimulated ACTH and cortisol secretion to a greater extent than did HS (P less than 0.05). The hormonal stimulation due to combined CRH and hypertonic saline was greater than that attributable to either factor alone (P less than 0.025), but was not different than the sum of the effects of the individual factors. These results indicate that increases in endogenous AVP produced by HS are associated with increases in both basal and CRH-stimulated ACTH and cortisol release. The effect of HS appears to be additive to but not consistently synergistic with the effect of CRH.

The responses of plasma immunoreactive ACTH (IR-ACTH), cortisol, GH, PRL, and LH to a single iv injection of 0.01-5 micrograms/kg human corticotropin-releasing factor (hCRF) were investigated in healthy volunteers. The lowest effective dose of hCRF was 0.5 micrograms/kg. hCRF caused brief pulse-like elevations of plasma IR-ACTH and cortisol without any effect on the plasma concentrations of GH, PRL, and LH. By contrast, ovine CRF (oCRF), given for comparison, produced long-lasting stimulation of the human pituitary-adrenal axis. The difference in duration of effect between hCRF and oCRF may be attributed to an approximately 3-4 times higher MCR of hCRF [7.9 +/- 1.2 (+/- SE) ml/kg min; n = 14] than oCRF (1.9 +/- 0.1 ml/kg min; n = 9) in man. No serious side effects occurred at any of the doses of hCRF tested. The highest dose (5 micrograms/kg) caused a slight increase of heart rate that was not associated with significant changes in arterial blood pressure. All subjects receiving 5 micrograms/kg and one third of the subjects receiving 1 micrograms/kg hCRF experienced a transient facial flush. We conclude that hCRF causes brief plasma ACTH and cortisol secretory episodes in man, similar to the physiological plasma ACTH and cortisol secretory episodes. This is in contrast to oCRF, which causes prolonged ACTH and cortisol secretion. These differences between the two peptides may be explained by the higher MCR of hCRF than oCRF.