Prognostic significance of the Ki-67 labeling index in growth hormone-secreting pituitary adenomas.

CONTEXT: Ki-67 is a marker of proliferation activity associated with invasiveness and prognosis in human tumors. OBJECTIVE: The aim of the study was to evaluate the Ki-67 index prognostic relevance in a group of acromegalic patients who underwent transsphenoidal surgery for a GH-secreting pituitary adenoma. MATERIAL AND METHODS: We selected 68 consecutive acromegalic patients referred to our hospital during a 5-yr period. The Ki-67 index was determined by immunohistochemistry on tissue samples obtained from each adenoma after surgery. Those patients who were not completely cured after surgery began medical therapy with somatostatin analogs (SSAs). Periodical pituitary magnetic resonance imaging and hormonal evaluation were performed during the follow-up. RESULTS: Twenty-eight of 68 patients were cured after surgery (41%). Among the 40 patients treated with SSAs, 13 were considered uncontrolled. Pituitary magnetic resonance imaging showed residual/recurrent disease in 25 of 68 patients after 6 months. No correlation was found between Ki-67 index and age, tumor size, GH, or IGF-I plasma levels. Tumors described as having cavernous sinus invasion had a higher mean Ki-67 index as compared with noninvasive tumors (P < 0.01). The Ki-67 index was significantly lower in tumors in patients cured after surgery as compared with patients considered not cured (P < 0.01) and in tumors in patients controlled by SSA therapy as compared with patients considered as uncontrolled (P < 0.05). CONCLUSION: The Ki-67 labeling index may predict clinical outcome in postsurgical management of acromegalic patients. We suggest routine Ki-67 evaluation in GH-secreting pituitary adenomas.

Dopamine receptor subtype 2 and somatostatin receptor subtype 5 expression influences somatostatin analogs effects on human somatotroph pituitary adenomas in vitro.

Dopamine (DA) and somatostatin (SRIF) receptor agonists inhibit growth hormone (GH) secretion by pituitary adenomas. We investigated DA subtype 2 receptor (DR2) and SRIF receptor (sst) subtypes 2 and 5 expression in 25 GH-secreting pituitary adenomas and tested in primary culture the effects on GH and prolactin (PRL) secretion of sst agonists selectively interacting with sst2 (BIM-23120), sst5 (BIM-23206), and sst2 and sst5 (BIM-23244). All adenomas expressed sst2; eight adenomas expressed both sst5 and DR2, eight sst5 but not DR2, and eight DR2 but not sst5. One tissue lacked expression of DR2 and sst5. GH secretion was inhibited by BIM-23120 in all samples, while it was reduced by BIM-23206 only in adenomas not expressing DR2. BIM-23120's inhibitory effects correlated with sst2 and DR2 expression, whereas DR2 expression correlated inversely with BIM-23206 inhibitory effects on GH secretion. In seven mixed GH-/PRL-secreting pituitary adenomas, PRL secretion was inhibited in sst5-expressing tumors by BIM-23206, but not by BIM-23120. BIM-23244 reduced PRL secretion only in adenomas expressing sst2, sst5 and DR2. sst5 and DR2 expression correlated directly with BIM23206 inhibitory effects on PRL secretion. Our results suggest that adenomas expressing DR2 are less likely to respond to clinically available SRIF analogs in terms of GH secretion inhibition. Therefore, drugs interacting also with DR2 might better control secretion of pituitary adenomas.

Androgen influences transforming growth factor-beta1 gene expression in human adrenocortical cells.

Sex steroid hormones have been shown to affect adrenocortical function and trophism, yet little is known about androgen action in human adrenocortical gland. In this study we examined the effects of androgens on transforming growth factor-beta1 (TGF/beta1) production by the human adrenocortical cell line, NCI-H295, which we recently demonstrated to express androgen receptor and whose growth is significantly reduced by dihydrotestosterone (DHT) treatment. TGFbeta1 is an important regulator of human adrenal development, with marked effects on steroid-producing cell function, and the production of distinct TGFbeta subtypes has been suggested to be regulated by steroid hormones in several tissues. To address potential TGFbeta1 induction by DHT, quantitative PCR and enzyme-linked immunoadsorbent assay were performed in NCI-H295 cells treated with DHT (from 10(-12)-10(-9) mol/L). DHT led to a significant dose-dependent increase in TGFbeta1 messenger ribonucleic acid expression and in biologically active TGFbeta1 protein levels in the conditioned media of NCI-H295 cells, demonstrating that androgen can induce TGFbeta1 expression and production. TGFbeta1 (10(-7)-10(-6) mol/L) was capable of significantly reducing cell proliferation (P < 0.05) after 24 h of treatment, as assessed by measuring [3H]thymidine incorporation in NCI-H295 cells. The addition of TGFbeta1-neutralizing antibody to cell cultures treated with different DHT concentrations (10(-9) and 10(-10) mol/L) blocked the inhibitory effect of TGF/beta1 on adrenocortical cell proliferation. These findings suggest that TGFbeta1 exerts an inhibitory action on adrenocortical cell proliferation. Therefore, it might be reasonable to suppose that DHT could also influence human adrenocortical cell growth by involving TGFbeta1.

Diurnal rhythm of plasma catecholamines in acromegaly.

We investigated the 24-h profiles of the circulating levels of norepinephrine (NE) and epinephrine (E), blood pressure (BP), and heart rate in 14 acromegalic patients, before (A) and 3-6 months after transsphenoidal surgery (C-A, cured; A-A, active), and in 8 age-matched normal subjects (N). In addition, the responses of NE, E, PRA, and aldosterone to upright posture were investigated. No significant differences in the mean 24-h plasma NE and E levels were observed between either group of acromegalics and the N subjects. Analysis of the 24-h profiles indicated a statistically significant 24-h rhythm of both NE and E in N subjects. No evidence of a 24-h rhythm of plasma NE and E and BP was found in A patients. After surgery, a statistically significant 24-h rhythm of NE was detected in the patients with acrophase (13.54 and 13.45 h in C-A and A-A patients, respectively) and mesor (1019.8+/-45.1 and 1017.8+/-54.7 pmol/L in C-A and A-A patients, respectively) similar to those observed in N subjects (acrophase, 13.21 h; mesor, 942.3+/-42.5 pmol/L). After surgery, the plasma concentration of E clearly fluctuated throughout the 24 h in both C-A and A-A patients, even if cosinor analysis failed to reveal a 24-h significant rhythm. A statistically significant 24-h rhythm of BP was restored only in C-A patients. The mean 24-h heart rate was slightly, but significantly (P<0.05), higher in A than in N subjects and decreased after surgery. No significant differences in upright-stimulated NE, E, and plasma aldosterone levels were observed between each group of acromegalics and N subjects. However, basal and upright-stimulated PRA levels were significantly (P<0.001) lower in A patients. In conclusion, our study demonstrates the lack of a clear circadian variation in catecholamine levels and BP in active acromegaly and the return of a significant 24-h rhythm of NE and BP after pituitary surgery, concomitant with the reduction in GH and insulin-like growth factor I serum levels.

Circadian profile of plasma calcitonin gene-related peptide in healthy man.

Calcitonin gene-related peptide (CGRP) is known to exert potent cardiovascular effects and is presumed to participate in the neural control of circulation and blood flow. It has been assayed in many physiological and disease conditions, yet virtually nothing is known of the normal fluctuations in its circulating levels. We have studied the variability throughout a 24-h period of plasma concentrations of CGRP in eight recumbent healthy volunteers (four men and four women, 25-37 yr old), after careful standardization of their daily diet and routine schedules. A correlation with the circadian rhythms of blood pressure (BP), heart rate (HR), and plasma aldosterone (PA), PRA, plasma cortisol (PC), and atrial natriuretic peptide (ANP) was also made. Plasma CGRP concentrations ranged from a mean peak value of 18.1 +/- 1.5 pmol/L to a mean lowest value of 11.7 +/- 0.4 pmol/L (P less than 0.05). The mean circadian acrophase of CGRP (calculated by cosinor analysis to occur at 2314 h) anticipated the corresponding acrophases of the other hormones (0122, 0528, 0809, and 0840 h for ANP, PRA, PA, and PC, respectively). Instead, BP and HR rhythms seemed to be antiphasic with the ANP rhythm (calculated acrophases occurred at 1356, 1339, and 1314 h for systolic BP, diastolic BP, and HR, respectively). Our data demonstrate that, like many other hormones, CGRP circulates in plasma with a circadian rhythm. There seems to be a temporal sequence starting with the nocturnal rise in plasma CGRP concentrations and progressing with the ensuing elevations of ANP, PRA, PA, and PC, whereas BP and HR are kept to their lowest values. These findings are in favor of a physiological role of CGRP in the complex regulation of BP homeostasis.

Modulatory effect of the renin-angiotensin system on the plasma levels of calcitonin gene-related peptide in normal man.

Calcitonin gene-related peptide (CGRP) has positive chronotropic and inotropic effects in animals and humans, and produces the most potent vasodilation known for an endogenous peptide. Yet, a physiological role for CGRP in the regulation of vascular tone and blood pressure has not been demonstrated. We studied the effects of 1) assumption of the upright position and 2) iv infusion of angiotensin-II (sequential doses of 8, 16, and 32 ng/kg.min, each dose for 20 min) in eight normal subjects (four men). Serial venous blood samples were taken to determine the plasma CGRP, epinephrine, norepinephrine, and aldosterone levels and PRA. Blood pressure and heart rate were continuously monitored at the finger with a Finapres 2300 instrument. After assumption of the upright posture, a quick rise in plasma CGRP levels was observed together with the expected increases in plasma norepinephrine and aldosterone and PRA. A transient increment was also observed for diastolic blood pressure and heart rate. Angiotensin-II infusion caused dose-dependent increases in plasma CGRP and aldosterone concentrations, already significant at the lowest infusion rate and parallel with the blood pressure rise. Plasma catecholamines significantly increased only at higher infusion rates. Our data demonstrate that modifications of plasma CGRP concentrations are part of the normal response to postural and vasomotor changes. These findings suggest a physiological role for CGRP in regulation of the peripheral vascular tone and possibly blood pressure in man.

Stress-induced activation of sympathetic nervous system is attenuated by the delta-opioid receptor agonist deltorphin in healthy man.

To examine the role of delta-opioid receptors in the regulation of the sympathoadrenomedullary system, the effects of the highly selective delta-opioid receptor agonist deltorphin (DT) on plasma catecholamine responses to insulin-induced hypoglycemia (IIH) and cold pressor test (CPT) have been investigated in normal subjects in two separate studies. DT failed to modify basal plasma levels of both norepinephrine (NE) and epinephrine (E). DT completely suppressed the IIH-evoked elevation of NE, whereas it attenuated the E response by 20%, with the DT-induced decrease in E release failing to achieve statistical significance. DT completely blocked the release of both NE and E elicited by CPT. We conclude that specific delta-opioid receptor stimulation exerts an inhibitory effect on NE release induced by both IIH and CPT. These findings provide evidence that delta-opioid receptors may influence the autonomic sympathetic reactivity.

Human galanin reduces plasma norepinephrine levels in man.

The neuropeptide galanin (GAL) is widely distributed in the peripheral and central nervous systems, where it often coexists with catecholamines. To gain insight into the action of human GAL on sympathetic nervous system activity in man, we investigated the effects of a 60-min infusion of human (h) GAL (80 pmol/kg.min) or saline on peripheral norepinephrine (NE) and epinephrine concentrations, heart rate (HR), and systolic and diastolic blood pressure (BP) in the supine position as well as after assumption of the upright posture (UP) in eight healthy male volunteers. hGAL depressed supine plasma NE (0.84 +/- 0.06 vs. 0.33 +/- 0.02 nmol/L) and blunted the NE response to assumption of the UP (1.68 +/- 0.03 vs. 0.44 +/- 0.03 nmol/L), but caused a significant enhancement of the epinephrine response to assumption of the UP (0.22 +/- 0.02 vs. 0.65 +/- 0.06 nmol/L). hGAL significantly increased supine HR (70 +/- 2 vs. 99 +/- 4 beats/min) and potentiated the HR response to assumption of the UP (82 +/- 3 vs. 107 +/- 4 beats/min). hGAL did not alter supine systolic and diastolic BP, but caused a significant decrease in the systolic (121 +/- 3 vs. 98 +/- 2 mm Hg) and diastolic (74 +/- 2 vs. 62 +/- 2 mm Hg) BP responses to assumption of the UP. Our data show that hGAL decreases supine position- and UP-stimulated release of NE, suggesting an inhibitory modulation of hGAL on sympathetic outflow in man. The finding that hGAL induces an increase in HR, both in the supine position and after UP, and an inhibition of the systolic and diastolic BP response to UP provides further support for an involvement of hGAL in regulation of the cardiovascular and autonomic nervous systems in man.

Effect of deltorphin on pituitary-adrenal response to insulin-induced hypoglycemia and ovine corticotropin-releasing hormone in healthy man.

To determine the role of delta-opioid receptors in the modulation of hypothalamic-pituitary-adrenal activity, we studied in normal subjects the effect of the highly selective delta-opioid receptor agonist deltorphin (DT) on the secretion of ACTH, cortisol, and arginine vasopressin in response to insulin-induced hypoglycemia. In an attempt to clarify the site of opiate modulation of ACTH secretion, we also studied in normal subjects the effect of DT on the ACTH response to ovine CRH-41. DT blunted the ACTH, cortisol, and arginine vasopressin responses to insulin-induced hypoglycemia, whereas it had no effect on the ACTH and cortisol responses to CRH. We conclude that DT-induced activation of delta-opioid receptors exerts an inhibitory influence on hypoglycemia-stimulated ACTH secretion. Based on the lack of an effect of DT on the ACTH response to CRH, we postulate that DT may modulate the secretion of ACTH through suprapituitary mechanisms.

Defective hypothalamic growth hormone (GH)-releasing hormone activity may contribute to declining GH secretion with age in man.

There is evidence that withdrawal of SRIH infusion in man promotes a rebound GH response that allegedly has been proposed to be related to the function of GHRH-producing neurons. In the present study we have evaluated whether a reduction in endogenous GHRH activity contributes to the decreased GH secretion of the elderly. Sixteen young (8 women, aged 23-32 yr, and 8 men, aged 18-27 yr) and 13 elderly (8 women, aged 65-82 yr, and 5 men, aged 65-70 yr) healthy subjects volunteered to participate in this investigation. Each subject was tested on 2 separate occasions: 1) a 90-min iv infusion of SRIH was given in 50 mL 0.9% saline delivered at a rate of 9 micrograms/kg.h; and 2) a 90-min iv infusion of isovolumetric amounts of 0.9% saline was given. Plasma GH levels were determined before and up to 180 min after SRIH or saline infusion, whereas plasma insulin-like growth factor I, estradiol, and testosterone levels were measured in basal samples. In elderly women, the mean maximum (delta) GH peak (2 +/- 0.7 micrograms/L) after withdrawal of SRIH infusion was significantly (P < 0.02) lower than that in young women (7.3 +/- 2 micrograms/L). In elderly men, the mean delta GH peak (2.9 +/- 0.6 micrograms/L) after withdrawal of SRIH infusion was lower than that in young men (6.3 +/- 1.6 micrograms/L), although the difference failed to achieve statistical significance. Baseline insulin-like growth factor I levels were significantly lower in elderly compared to young subjects in both men and in women. In women, both age and basal plasma estradiol and testosterone levels significantly correlated with delta GH peak after SRIH withdrawal (r = -0.61, r = 0.61, and r = 0.66, respectively), whereas in men they did not. These findings are compatible with the view that an age-related decrease in endogenous GHRH function may contribute to the defective GH secretion of the elderly. Alterations in plasma concentrations of sex steroids may have important implications in the observed changes.

Responses of plasma renin activity, aldosterone, adrenocorticotropin, and cortisol to dermorphin, a new synthetic potent opiate-like peptide, in man.

This study was designed to investigate the effect of dermorphin (D), a new synthetic potent opiate-like peptide (H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2), on PRA, plasma aldosterone (PA), plasma cortisol (PC), and plasma ACTH levels in normal men. D infusion (5.5 micrograms/kg X min for 30 min) significantly increased PRA (P less than 0.01) and decreased PC levels (P less than 0.02). D produced a small decrease in ACTH and a small increase in PA. Pretreatment with the opioid receptor antagonist naloxone (N) blunted the D-induced PRA increase and completely prevented the D-induced PC decrease, but enhanced PC and ACTH levels. These data indicate that the action of D is mediated through opioid receptors, and are consistent with the conclusion that 1) D, a new opioid peptide, increases PRA levels, perhaps via activation of the sympathetic nervous system, providing evidence that opioid peptides may exert an influence on renin secretion; and 2) D suppresses PC levels, perhaps by affecting ACTH secretion, corroborating previous observations that opioid peptides might affect the function of the pituitary-adrenocortical axis.

Prolactin-releasing activity of dermorphin, a new synthetic potent opiate-like peptide, in normal human subjects.

Dermorphins (D) are heptapeptides (H-Tyr-D-Ala-Phe-Gly-Tyr-X-Ser-NH2; X, Pro or Hyp) with powerful central and peripheral opiate-like activity, originally isolated from the skin of South American frogs. To study the effect of a synthetic D on PRL secretion in man, either D (5.5 micrograms/kg . min for 30 min) or D-placebo (0.9% saline) infusion over 30 min was administered iv in random sequence to 11 volunteers (6 women and 5 men). In all the subjects, D induced a significant increase in the levels of PRL, more consistently in women than in men. To investigate whether the increase in PRL was due to the opiate agonist properties of D, the study was repeated in the same subjects during naloxone infusion. The PRL response to D was completely suppressed, suggesting that the peptide exerts its effect on PRL release via an opiate receptor stimulation of the mu-type. These data allow us to conclude that D may affect PRL release in humans; however, further investigation is necessary before any physiological significance might be attributed to D in man.

Somatostatin reduces 3H-thymidine incorporation and c-myc, but not thyroglobulin ribonucleic acid levels in human thyroid follicular cells in vitro.

The action of somatostatin (SRIH) on 3H-thymidine (thy) incorporation and on c-myc and thyroglobulin RNA levels in a suspension of follicles from normal and goitrous human thyroid was examined. SRIH, at 10(-7) M concentration, inhibited basal thy incorporation (maximally by 4 h lasting for up 24 h), which effect was greater in goiter than in normal thyroid and was also detected in growing adherent epithelial cells. Moreover, in a follicle suspension SRIH prevented TSH-stimulated thy incorporation, both in normal and in goitrous thyroid. Basal expression of c-myc RNA was not affected by SRIH in either tissue, whereas the TSH-stimulated c-myc RNA level was significantly reduced in goiter. No effect of SRIH was observed on basal or TSH-stimulated thyroglobulin RNA levels. SRIH did not alter basal cAMP concentrations in normal or goitrous follicles, but it significantly reduced TSH-stimulated cAMP accumulation both in normal thyroid and in goiter. Overall, our data indicate a direct inhibitory action of SRIH on growth, but not on differentiation, of human thyroid, probably by a mechanism not entirely cAMP dependent.

Blood growth hormone-binding protein levels in premenopausal and postmenopausal women: roles of body weight and estrogen levels.

A substantial proportion of GH circulates bound to high affinity GH-binding protein (GHBP), which corresponds to the extracellular domain of the GH receptor. Current evidence indicates that nutritional status has an important role in regulating plasma GHBP levels in humans. In the present study the relationship among plasma GHBP levels, body composition [by bioelectrical impedance analysis (BIA) and dual energy x-ray absorptiometry (DEXA)] and serum estradiol (E(2)) was evaluated in premenopausal (n = 92) and postmenopausal (n = 118) healthy women with different body weight [three groups according to body mass index (BMI): normal, 18.5-24.99; overweight, 25-29.99; obese, 30-39.99 kg/m(2)]. Plasma GHBP levels were measured by high pressure liquid chromatography gel filtration. GH and insulin-like growth factor I levels were determined by immunoradiometric assay and RIA, respectively. GHBP levels were significantly higher in premenopausal women with BMI above 25 kg/m(2) (overweight, 3.789 +/- 0.306 nmol/L; obese, 4.372 +/- 0.431 nmol/L) than those observed in postmenopausal women (overweight, 1.425 +/- 0.09 nmol/L; obese, 1.506 +/- 0.177 nmol/L). No significant differences were found between normal weight premenopausal (1.741 +/- 0.104 nmol/L) and postmenopausal (1.524 +/- 0.202 nmol/L) women. In premenopausal women GHBP levels correlated positively with BMI (r = 0.675; P < 0.001), fat mass (FM; r = 0.782; P < 0.001; by BIA; r = 0.776; P < 0.001; by DEXA), truncal fat (TF; r = 0.682; P < 0.001), waist to hip circumference ratio (WHR; r = 0.551; P < 0.001), and E(2) (r = 0.298; P < 0.05), whereas no significant correlation was found in postmenopausal women between GHBP levels and BMI, FM, TF, WHR, or E(2). In normal weight pre- and postmenopausal women GHBP levels did not change between the ages of 20 and 69 yr. No statistically significant correlation was found between GHBP and age for all groups studied. Moreover, in two distinct subgroups of pre- and postmenopausal women, aged 40-49 yr, the direct relationship between GHBP levels and all indexes of adiposity were only observed in premenopausal women [BMI: r = 0.836; P < 0.001; FM: r = 0.745 (BIA) and r = 0.832 (DEXA); P < 0.001; TF: r = 0.782; P < 0.001; WHR: r = 0.551; P < 0.05], but not in postmenopausal women. In conclusion, the present data indicate a strong direct correlation between GHBP and body fat in premenopausal, but not in postmenopausal women, whereas they failed to detect a relationship between GHBP and age. Therefore, these results suggest that endogenous estrogen status may be an important determinant of the changes in GHBP levels in women with different body weights.

Somatostatin receptor subtypes 2 and 5 differentially affect proliferation in vitro of the human medullary thyroid carcinoma cell line tt.

Somatostatin and its receptors (SSTR1 to SSTR5) are expressed in normal human parafollicular C cells and medullary thyroid carcinoma (MTC), but the role of SSTR subtypes in cell growth regulation is still not clear. The present study demonstrates that the human MTC cell line TT stably expresses all the SSTR subtypes and responds to SSTR2 and SSTR5 activation by subtype-selective agonists with two different patterns in terms of [(3)H]thymidine ([(3)H]thy) incorporation and cell number. The SSTR2 preferential agonists (BIM-23120, BIM-23197, BIM-23190, and BIM-23014; 10(-9)-10(-6) M), significantly suppressed [(3)H]thy incorporation (58-13%) and reduced cell proliferation (50-28%), whereas the SSTR5-selective agonist, BIM-23206 (10(-9)-10(-6) M), significantly increased [(3)H]thy incorporation in TT cells (80-175%), but failed to influence cell proliferation. SSTR2 antagonist (BIM-23627) counteracted the action of SSTR2 preferential agonists on TT cells. Furthermore, increasing concentrations of SSTR5-selective agonists, BIM-23206, dose-dependently prevented the suppression of TT cell [(3)H]thy incorporation and proliferation produced by SSTR2 preferential agonist, BIM-23120, showing an antagonism between these compounds. The following conclusions were reached: 1) the human MTC cell line TT expresses all SSTR subtypes; 2) SSTR2 activation inhibits DNA synthesis and cell proliferation, whereas SSTR5 activation increases DNA synthesis; and 3) SSTR2 preferential agonist (BIM-23120) can antagonise SSTR5-selective agonist (BIM-23206) action and vice versa. These findings suggest a tissue-specific function and a tissue-specific interaction between the two receptors.

Evidence that enhancement of cholinergic tone increases basal plasma levels of calcitonin gene-related peptide in normal man.

To investigate the influence of the cholinergic system on the modulation of the circulating levels of calcitonin gene-related peptide (CGRP) under basal conditions in normal man, the effects of an acetylcholinesterase inhibitor, pyridostigmine bromide, and a muscarinic receptor blocker, pirenzepine, were studied in 16 normal subjects (8 females and 8 males). Pyridostigmine (120 mg, orally) induced a significant (P < 0.01) rise in basal plasma CGRP, while it reduced systolic and diastolic blood pressure. In all subjects, pirenzepine (0.6 mg/kg, i.v. bolus) was unable to modify the basal CGRP level. In conclusion, a pharmacologically induced enhancement of cholinergic tone resulted in an increase in CGRP, whereas muscarinic receptor blockade had no effect on CGRP levels or blood pressure. Therefore, the cholinergic system seems to be involved in the control of CGRP release in man, acting as a positive modulator. However, the available data do not indicate that there is a tonic cholinergic tone responsible for CGRP secretion under physiological conditions.

Diurnal blood pressure variation and hormonal correlates in fatal familial insomnia.

Fatal familial insomnia is a prion disease in which a selective thalamic degeneration leads to total sleep deprivation, hypertension, dysautonomia, adrenal overactivity, and impaired motor functions. With patients under continuous recumbency and polysomnographic control, we assessed the changes in the 24-hour patterns of blood pressure, heart rate, plasma catecholamines, corticotropin, and serum cortisol in three patients at different stages of the disease. Six healthy volunteers were used as control subjects. A dominant 24-hour component was detected at rhythm analysis of all variables, both in patients and control subjects. In the patients, the amplitudes gradually decreased as the disease progressed, leading to the obliteration of any significant dirunal variation only in the preterminal stage. A shift in phase corresponded to the loss of the nocturnal fall in blood pressure in an early stage of the disease, when nocturnal bradycardia was still preserved. Plasma cortisol was high and became increasingly elevated, whereas corticotropin remained within normal levels; abnormal nocturnal peaks appeared in their circadian patterns. The disrupted patterns of cortisol and blood pressure preceded the development of hypertension and severe dysautonomia, which in turn were paralleled by increasing catecholamine and heart rate levels. Our data demonstrate that in patients with fatal familial insomnia the changes detectable in the rhythmic component of diurnal blood pressure variability result in a pattern of secondary hypertension. Disturbances in thalamic, pituitary-adrenal, and autonomic functions seem to be involved in mediating these changes.

Progressive disruption of the circadian rhythm of melatonin in fatal familial insomnia.

Fatal familial insomnia (FFI) is a disease characterized by loss of sleep activity due to selective thalamic degeneration. To assess the secretory pattern of melatonin (MT) in FFI, we studied two cases of overt disease under standardized conditions and polysomnographic control. Each patient underwent repeated 24-h study sessions, and MT was assayed at 30-min intervals. Six healthy volunteers were used as controls. Slow wave sleep was never recorded, whereas occasional episodes of enacted dreaming accompanied by rapid ocular movements and complex muscular activities were documented, with no detectable rhythm. Plasma MT concentrations gradually decreased as the disease progressed. A significant circadian rhythm was detected in the earlier recordings, with decreasing amplitudes with disease progression. Complete rhythm obliteration was achieved in the most advanced stage. Normally placed nocturnal acrophases were detected in the earlier stages, but then a shift toward the daytime hours was observed. Thalamic lesions of FFI appear to determine a progressive disruption of the sleep/wake cycle accompanied by decreased circulating levels of MT, with progressive alterations in the circadian rhythm of this hormone. On the other hand, decreased secretion of MT may contribute to the sleep disturbances of FFI.

Dermorphin reduces the metyrapone-evoked release of adrenocorticotropin, beta-endorphin, and beta-lipotropin in man.

The aim of this study was to investigate further the influence of dermorphin (D), a new potent opioid peptide (H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2), on the functional activity of the pituitary-adrenocortical system in man. Six normal men were treated with oral metyrapone to stimulate the secretion of ACTH, beta-lipotropin, and beta-endorphin. In these subjects, significant suppression of metyrapone-evoked release of ACTH and related peptides occurred during D infusion (5.5 micrograms/kg X min for 30 min) compared with that during saline infusion. These results indicate that D can induce a significant decline in plasma levels of ACTH, beta-lipotropin, and beta-endorphin, the major circulating peptides from the C-terminal part of proopiocortin, and suggest that opioid peptides may be involved in the control of the functional activity of pituitary-adrenocortical activity in man.

Circadian rhythm of calcitonin gene-related peptide in uncomplicated essential hypertension.

OBJECTIVE: To assess the existence of an altered circulating pattern of calcitonin gene-related peptide (CGRP) in hypertension. DESIGN: The 24 h variation in plasma CGRP was measured and compared in 10 patients affected by uncomplicated essential hypertension and in nine age- and sex-matched healthy volunteers. The diurnal variations in blood pressure, atrial natriuretic peptide (ANP), plasma renin activity (PRA), plasma aldosterone and plasma cortisol were also assessed. METHODS: Recumbency studies were performed under standardized, drug-free conditions beginning at 0800 h. Venous samples were drawn every 4 h for 24 h and hormone levels were assessed with specific radioimmunoassays. The blood pressure was measured every 15 min with a SpaceLabs 90207 monitor. RESULTS: The mean 24-h plasma CGRP concentrations were significantly lower in the hypertensive group than in the control group. In both groups a circadian rhythm was present with the same pattern, but at a lower level in hypertension. A temporal sequence starting with the nocturnal rise in plasma CGRP concentrations and progressing with the elevations of ANP, PRA, and plasma aldosterone and cortisol was apparent in both groups. The nocturnal rise in the CGRP and ANP concentrations coincided with the blood pressure and the heart rate falls. CONCLUSIONS: Our data show that CGRP is lower than normal but maintains its circadian variability and its relationship with the diurnal variations in blood pressure and other hormones known to be active on the cardiovascular system.