Novel Treatments for Obesity: Implications for Cancer Prevention and Treatment

It is now established that obesity is related to a higher incidence of cancer during a lifespan. The effective treatment of obesity opens up new perspectives in the treatment of a relevant modifiable cancer risk factor. The present narrative review summarizes the correlations between weight loss in obesity and cancer. The current knowledge between obesity treatment and cancer was explored, highlighting the greatest potential for its use in the treatment of cancer in the clinical setting. Evidence for the effects of obesity therapy on proliferation, apoptosis, and response to chemotherapy is summarized. While more studies, including large, long-term clinical trials, are needed to adequately evaluate the relationship and durability between anti-obesity treatment and cancer, collaboration between oncologists and obesity treatment experts is increasingly important.

[Thyrotoxic hypokalemic periodic paralysis: a rare complication of a common disease]

Thyrotoxic periodic paralysis (TPP) is an uncommon but potentially lethal manifestation of hyperthyroidism characterized by muscle paralysis and hypokalemia. We have reported 3 cases of TPP in male patients, which manifested with morning muscle weakness evolved into paralysis. In all patients were found severe hypokalemia, abnormalities on electrocardiogram, and Graves' hyperthyroidism. Intravenous potassium administration led to normalization of potassium levels, and resolution of neurological symptoms. In addition, beta blockers and methimazole were started. Two patients required total thyroidectomy for poor control of hyperthyroidism with antithyroid drug. In patients presenting with periodic paralysis or diffuse muscle weakness thyroid function should be investigated in order to find out the cases secondary to unknown hyperthyroidism and to start an early appropriate combined therapy. The correct management of TPP can prevent serious cardiopulmonary complications.

Nitric oxide biphasically modulates GH secretion in cultured cells of GH-secreting human pituitary adenomas

BACKGROUND

Nitric oxide (NO) biphasically modulates osteoclast function, sperm motility and testosterone production by exerting a positive effect at low concentrations and a negative effect at high concentrations. In this study the effect due to administration of four NO-donors, each releasing an individual amount of NO, was studied on GH secretion from human adenomatous GH-secreting cells.

METHODS

Sodium nitroprusside (SNP), diethylenetriamine NO adduct (DETA/NO), diethylamine/NO complex sodium salt (DEA/NO), and S-nitroso-N-acetylpenicillamine (SNAP) were administered at a concentration of 10-4 M to cells isolated after transsphenoidal adenomectomy from five acromegalic patients.

RESULTS

SNP significantly (p < 0.01) increased GH secretion, while the other NO donors inhibited GH secretion in comparision with the amount of GH spontaneously released by unstimulated cells. Each drug showed an individual degree of inhibitory potency: DEA/NO > DETA/NO > SNAP. Nitrite accumulation in the media was measured as a marker of NO released by each individual drug and was found to be different for each drug (DEA/NO > DETA/NO > SNAP > SNP). A negative correlation (R = -0.93; p < 0.05) was found between nitrite release and GH secretion induced by each drug.

CONCLUSIONS

These data show that low and quasi-physiological levels of NO, such as those released by SNP, stimulate GH secretion, while high NO levels, such as those released by the other NO-donors, inhibit GH secretion. Thus, NO is shown to be able to modulate GH secretion in a dose-dependent manner in GH adenomatous cells from human pituitary adenomas.

Biphasic effect of nitric oxide on testosterone and cyclic GMP production by purified rat Leydig cells cultured in vitro

Nitric oxide (NO) biphasically modulates osteoclast function and sperm motility by exerting a positive effect at low concentrations and a negative effect at high concentrations. We therefore tested whether NO exerts a comparable effect on testosterone secretion by cultured rat Leydig cells. Three NO-donors, S-nitroso-N-acetylpenicillamine (SNAP), diethylamine/nitric oxide complex sodium salt (DEA/NO) and diethylenetriamine nitric oxide adduct (DETA/NO) were administered in a wide range of concentrations (10(-8)-10(-3) M for 3 h) to Percoll-purified Leydig cells from adult rats. These drugs raised testosterone and cGMP secretion when used at low concentrations (10(-8)-10(-5) M); however, they inhibited testosterone, but did not affect cGMP, secretion at concentrations higher than 10(-5) M. Administration of the NO scavenger haemoglobin (160 micrograms/mL) prevented both the stimulatory and the inhibitory effect of these drugs. Nitrite accumulation was measured as a marker of NO released by the drugs in our in vitro system; it fell within the range of control media in the presence of NO-donor concentrations lower than 10(-5) M, but was several-fold higher in the media of cells treated with concentrations of the NO-donors greater than 10(-5) M. These data show that (1) NO exerts a biphasic effect on testosterone secretion, which is stimulatory at low and inhibitory at high concentrations; (2) the stimulatory effect of NO is mediated by cGMP, the classic second messenger for NO action.

Impact of recombinant human growth hormone treatment on psychological profiles in hypopituitary patients with adult-onset growth hormone deficiency

BACKGROUND

We examined the effect of growth hormone (GH) administration on the psychological capacity and sense of well-being in 25 patients with adult-onset GH-deficiency (GHD).

METHODS

Very low dosages [0.5-1.0 UIday(-1) s.c. at bed-time] of recombinant human (rh)-GH (n = 13; aged 50+/-15 years, mean+/-SD) or placebo (n = 12, 53+/-14 years) were given at random for a 6-month period. Quality of life was assessed by using the Italian version of the self-rating Kellner Symptom Questionnaire (KSQ) and the Hamilton Depression Scale (HDS).

RESULTS

No difference in insulin-like growth factor I (IGF-I) levels was noted between groups on entry to the study. A significant increase in IGF-I [month 0 56.2+/-10.4 microg L(-1) vs. month 6 125.7+/-16.7 microg L(-1); P < 0.001] levels was noted only in the rh-GH-treated group. There was no difference in overall scores on the KSQ between the rh-GH-treated and control groups on entry. A slight, non-significant, decrease in overall scores was noted in both groups of subjects. Subsection analysis of items from the KSQ did not show significant differences in either group during the 6-month period. A significant decrease (month 0 28+/-1 vs. month 6 25+/-1; P = 0.02) in the HDS score was noted in rh-GH-treated but not in placebo-treated patients. There was a significant correlation (rs, -0.56, P = 0.05) between increase in IGF-I levels and decrease in HDS scores in rh-GH treated patients.

CONCLUSION

The data demonstrate that low rh-GH dosages significantly improve psychological profiles as rated by HDS evaluation in adult-onset patients with GHD. On the other hand, a 6-month period of treatment does not produce any significant differences in quality of life as measured by KSQ between treated patients and placebo controls.

Nitric oxide modulates in vivo and in vitro growth hormone release in acromegaly

Nitric oxide (NO) has recently been shown to modulate pituitary secretion both in vivo and in vitro. The aim of this study was to investigate the effects of this chemical transmitter on spontaneous and growth-hormone-releasing hormone (GHRH)-induced growth hormone (GH) secretion in acromegalic patients, as well as from GH-secreting tumors maintained in vitro. The study was carried out in 7 acromegalic patients (46.2 +/- 2 years) and in 5 normal subjects (40.1 +/- 1.5 years). GH and prolactin (PRL) secretion were assayed during the administration of isosorbide dinitrate (ID, 5 mg, orally), an NO donor, GHRH, and ID plus GHRH. During ID, a significant (p < 0.05) increase (37%) over basal GH levels was only observed in acromegalics. There was no change in GH levels in response to GHRH or ID plus GHRH in either group. No significant change in PRL levels was observed in either group during ID, while GHRH, with or without ID, induced a slight increase in PRL levels in acromegalics only. Tumor specimens were obtained by selective transsphenoidal adenomectomy, and the cells were plated and incubated for 1, 2 and 24 h in the presence of sodium nitroprusside, a releaser of NO (SNP, 0.3 or 0.6 mM), of GHRH (10-8 M) or of both. SNP significantly (p < 0.001) increased GH levels in a dose-dependent manner (R = 0.99, p = 0.02), but was unable to modify the GH response to GHRH. In acromegalics, a significant correlation (R = 0.822, p < 0.045) and a correlation near the limit of significance (R = 0.73, NS) were observed respectively between the in vivo GH response to ID and the in vitro response to SNP at 24 h. No significant effect was observed on PRL secretion during SNP incubations, while GHRH produced a significant increase in PRL after 2 and 24 h incubation in acromegalics. These observations indicate that NO plays a stimulatory role in vivo and in vitro on GH secretion in acromegalic patients.

Immunoreactive endothelin in nodular pathology of the thyroid

OBJECTIVES

Endothelins (ETs) can act as autocrine and/or paracrine regulators of thyroid homeostasis and growth. The aim of this study was to evaluate immunoreactive ET (i-ET) levels in a group of patients with nodular pathology of the thyroid and to correlate them with the cytomorphological features after fine-needle aspiration (FNA) and with hormonal and immunological status and blood pressure levels.

DESIGN

Plasma and cystic i-ET were assayed in a group of patients with varying thyroid function, who underwent FNA for solid and cystic nodular pathology.

PATIENTS

47 patients (32-81 years) with nodular pathology of the thyroid and 18 controls (28-70 years) with normal thyroid function and morphology were studied.

MEASUREMENTS

Fasting venous blood samples were collected and the plasma for i-ET was frozen at -80 degrees C until assayed. Sera were frozen at -20 degrees C for FT3, FT4, TSH, TPO autoantibodies and thyroglobulin autoantibodies assay. Cystic fluid was obtained by FNA, centrifuged, and the supernatant was stored at -20 degrees C until i-ET assay. FNA cytology was examined by light microscopy.

RESULTS

In patients with cystic nodules, plasma i-ET levels were significantly (P = 0.002) higher (5.7 +/- 1.1 ng/l, +/- SEM) than in both patients with solid nodules (2.6 +/- 0.4 ng/l) and (P = 0.02) controls (3.0 +/- 0.3 ng/l). In patients with cystic nodules, cystic i-ET levels (12.6 +/- 1.9 ng/l) were significantly (P = 0.003) higher than plasma levels (5.7 +/- 1.1 ng/l) and did not correlate with the percentage of FNA cellularity. i-ET levels in cystic fluid (12.6 +/- 1.9 ng/l) were significantly (P = 0.0001) higher than plasma i-ET levels in both patients with solid nodules and controls. No difference in either plasma or cystic i-ET levels was found in patients with cystic nodules in relation to differences in thyroid function. No difference in plasma i-ET levels was found between patients with solid nodules and controls. In controls, no significant difference in plasma i-ET levels was found between males and females. A negative correlation (r = -0.55, P = 0.02) was found between cystic i-ET levels and systolic and diastolic blood pressure. No correlation between cystic or plasma i-ET levels and FT3, FT4 or TSH was found in any of the subjects studied.

CONCLUSIONS

It seems that endothelins do not possess a primary role in determining thyroid function and that the increased levels in cystic fluid found in our subjects could be secondary to cystic nodule development.

Effects of sumatriptan on growth hormone releasing hormone-stimulated growth hormone secretion in acromegaly

Sumatriptan (SU), a specific 5-HT1D receptor agonist, was recently shown to be able to increase growth hormone (GH) levels in normals, but not in acromegalics, while no effect was seen on prolactine (PRL). SU is also able to produce an increase in GH response to growth hormone releasing hormone (GHRH) in prepubertal children. In this study we investigated whether SU administration influences GHRH-induced GH secretion in 8 acromegalics, and 6 age-matched normal volunteers, as a control group. We evaluated the effects of SU (6 mg s.c.) or placebo (PL) administration on GHRH (1 microgram/kg bw i.v.)-induced GH and PRL secretion. After SU priming the GH response to GHRH did not changed in acromegalics, but significantly decreased in controls, in comparison with that observed after PL plus GHRH. In acromegalics, no difference in GH peak was seen after SU plus GHRH and PL plus GHRH, nor was any difference seen in AUC between tests. In controls, no difference was seen in GH peaks, while SU priming significantly (P < 0.03) decreased the AUC 90-120 min of GH after GHRH administration. In acromegalics, SU did not change the slight GHRH-induced increase in PRL levels. Our study documents that 5-HT1 D receptors do not interfere with GHRH-stimulated GH secretion in acromegalic subjects. In normals, SU is able to decrease GH response to GHRH, thus confirming that 5-HT1D receptors are able to modulate GH secretion in normals.

Effects of six-month administration of recombinant human growth hormone to healthy elderly subjects

In aging, both changes in body composition and a decrease in GH secretion are observed. While recombinant human GH (rhGH) therapy was shown to be effective in GH-deficient adults, its effects on normal aging are controversial. This study addressed the effects of six-month administration of low dosages of rhGH in a group of 5 healthy elderly subjects (age range 71-86 years). All subjects received 2 IU rhGH (Saizen, Serono) x 2/week s.c., which was approximately 0.03 mg/kg/week, and were examined before and 1, 3, and 6 months after the start of the therapy, as well as 3 months after therapy was suspended. Hormonal, metabolic and biochemical parameters, as well as bone density at the forearm level, body composition and muscle strength, assessed by isokinetic exercises, were evaluated at each scheduled visit. After the start of the therapy, there was an average 9 +/- 3% increase (median 8%) in IGF-I levels (IGF-I basal: 145.6 +/- 9 ng/mL, IGF-I peak: 176.0 +/- 10; p < 0.001). An increase in lean body weight, a decrease in fat (p < 0.05), and an improvement in muscle strength (p < 0.01) were recorded. No significant variation was observed in the metabolic parameters. During rhGH therapy, an increase in both bone resorption and formation parameters, and a slightly decreasing trend in bone density were noted. In conclusion, low dosages of rhGH in healthy elderly subjects seem to determine some physiological effects, such as a slight increase in IGF-I levels, which in turn may be responsible for the positive effects on body mass composition and muscle strength, without producing side effects. On the other hand, 6-month subcutaneous rhGH therapy at the dosage employed was unable to improve bone density.

Hexarelin is a stronger GH-releasing peptide than GHRH in normal cycling women but not in anorexia nervosa

Anorexia nervosa (AN) is a chronic disease in which an enhanced GH response to GHRH, a paradoxic increase after TRH and LHRH, and low IGF1 levels may be present according to the patient's clinical state. It is well known that the GH hypersecretory state commonly found in the "acute phase" of AN is restored with weight gain. The new synthetic hexapeptide, Hexarelin (HEX), which is chemically similar to GH-releasing peptide 6, has recently been shown to possess a stronger GH-releasing activity than GHRH in humans and to share a synergistic effect with GHRH when administered intravenously. Indeed, HEX shows a slight cortisol and PRL-releasing activity. The aim of the study was to evaluate the effect of i.v. administration of old (GHRH) and new (HEX) GH-releasing peptides on GH, PRL and cortisol secretion in 9 AN patients in the "recovery phase" of the disease, after partial but significant weight gain. For controls we studied 7 normal cycling women. No significant difference in GH secretion after GHRH was found between AN and controls. GHRH was not able to release cortisol or PRL either in AN or controls. HEX produced a significantly (p < 0.05) higher GH peak in controls than in AN, while GH AUC was slightly but not significantly higher. Indeed, only in controls, HEX was a stronger GH-releasing peptide than GHRH. These findings could be explained by the fact that, in AN, GH secretion is already stimulated both by reduced IGF1 levels and by increased GHRH/somatostatin ratio. As reported in the literature, the action of HEX action is only slightly influenced by variations in somatostatin tone. It therefore appears likely that the absolute or relative GHRH increase present in AN could partially mimic the unknown hypothalamic factor necessary for HEX action on the hypophisis and that, following a structural modification of pituitary HEX receptors, GHRH would become able to bind to HEX receptors on somatotropic cells. Consequently, the pituitary cells would already be over-activated and so unable to respond maximally to HEX stimulation. Indeed, in AN, GHRH might play a role of negative modulation in the control of HEX action. Finally, in our study HEX was able to produce a persistent PRL release in controls but not in AN, thus suggesting that its action could be partially dependent on the estrogen milieu, while it stimulated cortisol secretion only transiently in the patients studied.

LH isoform profiles during short-term pulsatile LHRH administration in elderly men

LH isoform profiles were analyzed in sera resolved with isoelectrofocusing from 5 elderly men (age 70.6 +/- 2.95) and 5 young adult men (age 28.2 +/- 1.24), by using polyclonal antibodies (RIA), monoclonal antibodies directed against the beta-subunits (IRMA) and in vitro LH bioassay. Despite the fact that the elderly had lower testosterone levels than the young (293 +/- 38 vs 512 +/- 77 ng/dl, p < 0.05), no differences were noted in the isoforms detected by any of the assays, although each assay yielded a characteristic profile. Indeed, RIA showed most LH in the acidic range, while IRMA revealed LH profiles with a major peak in the basic range, thus resembling the profiles determined by means of the bioassay. In the elderly, the profiles were also analyzed on day 7 and day 14 of short-term pulsatile sc LHRH administration (150 ng/bw/120 min). Only the LH bioassay detected an LHRH-induced shift to more basic and bioactive forms; these changes accompanied an increased in testosterone levels on day 7 (396 +/- 83 ng/dl, p < 0.05 vs day 0) and on day 14 (320 +/- 58 ng/dl NS vs day 0). Our data suggest that: 1) the profiles obtained in young and elderly subjects are similar, irrespective of the antisera used; 2) as a result of treatment with LHRH in the elderly an increase in T levels occurs, possibly due to the observed changes in LH bioactivity; 3) the in vitro LH bioassay appears to be the most sensitive assay in detecting such changes, which consisted of an enrichment in more basic and bioactive glycoforms.

Lack of effect of desmopressin on ACTH and cortisol responses to ovine corticotropin-releasing hormone in anorexia nervosa

Both arginine vasopressin (AVP) and corticotropin-releasing hormone (CRH) are involved in the release of ACTH in man. Desmopressin (DDAVP), a synthetic analogue of AVP, has been shown to have a CRH-like action (able to promote ACTH and cortisol release) in animals but not in normal man. Nevertheless, DDAVP is able to release ACTH and cortisol in ACTH-dependent Cushing's disease. We studied eight anorexia nervosa (AN) patients [as AN is a condition in which chronic activation of the hypothalamic-pituitary-adrenal (HPA) axis is commonly reported] in a refeeding phase of the disease, to evaluate whether, after weight gain, ACTH and cortisol response to ovine corticotropin-releasing hormone (oCRH) [1 microgram i.v. DDAVP alone and as pretreatment to oCRH (1 microgram kg-1 BW i.v.)-induced secretion of ACTH and cortisol. We studied six normal women as control subjects. No significant differences in ACTH and cortisol responses to oCRH were found between AN patients and control subjects. DDAVP was not able to stimulate ACTH or cortisol release in AN patients or in control subjects, but in the latter it was able to significantly enhance (P < 0.05) ACTH [area under curve (AUC): 590.0 +/- 104.4 pmol L-1 120 min-1] and cortisol (AUC: 28899.0 +/- 6935.2 nmol L-1 120 min-1) responses to oCRH (ACTH AUC: 325.7 +/- 101.7 pmol L-1 120 min-1, cortisol AUC: 14197.4 +/- 2930.0 nmol L-1 120 min-1). The present data show that DDAVP does not stimulate ACTH and cortisol in AN patients or, as previously reported, in normal subjects. However, DDAVP is able to enhance ACTH and cortisol release after oCRH administration in normal subjects but not in AN patients. This finding could be due to a down-regulation of hypophyseal DDAVP V3 receptors in AN as a direct consequence of the hypercortisolaemic status usually present.

Effectiveness and tolerability of slow release lanreotide treatment in active acromegaly: six-month report on an Italian multicenter study. Italian Multicenter Slow Release Lanreotide Study Group

The objective of the study was to determine the tolerability and effectiveness of the slow release (SR) somatostatin analog lanreotide in active acromegaly. Fifty-seven patients, unselected in terms of their previous responsiveness to octreotide therapy, were included in a prospective, open label study carried out at 6 Italian endocrinological centers. The effects of 6 months of SR lanreotide, given at first every 14 days at a dosage of 30 mg, im, were recorded. In some patients (33%), drug dosage was adjusted by increasing the dose (to 60 mg, im) and/or shortening the time interval (every 10 days) of SR lanreotide administration. Fifty patients completed the 6-month period of therapy; 2 subjects dropped out because of adverse events, and 5 dropped out because of ineffectiveness after changes in drug administration. The first SR lanreotide injection produced more than 50% suppression of GH levels from the basal value in 93% of patients. Thirteen days later, baseline GH levels were reduced by over 50% in 25% of patients. Mean GH values were normalized in 85% of patients after 6 months, whereas insulin-like growth factor I (IGF-I) levels were normalized in 38% of patients. No correlation was found between pretreatment GH levels and GH response to SR lanreotide or between changes in GH and IGF-I during therapy. During treatment, there was a significant reduction in the percentage of patients complaining of joint pain, hyperhydrosis, and paresthesias. Changes in soft tissue swelling were documented by significant decreases in finger measurements. Diarrhea and abdominal pain were the most frequent side-effects when therapy was started; these progressively decreased. After the first month of therapy, moderate, mild, and no side-effects were reported by 3%, 40%, and 53% of patients. A nonsignificant increase occurred in asymptomatic gallstones and amylase levels. Minimal changes were noted in carbohydrate tolerance, consisting of a slight increase in glycosylated hemoglobin, a rise in glucose and a decrease in pre- and postprandial insulin levels. No effects on PRL, free cortisol, TSH, or free thyroid hormone levels were noted. No significant change in the percentage of visual field abnormalities was noted. Decreases in pituitary tumor size occurred in 3 of 17 patients reevaluated after 6 months of therapy. The 6-month period of SR lanreotide therapy was compared, on an anamnestic basis, with a 6-month or longer period of sc octreotide therapy (median, 300 micrograms/day) in 34 patients. There were no differences in effectiveness or tolerability between the 2 somatostatin analogs. These data indicate that SR lanreotide at a dose of 30 mg, im, every 14 days is an effective treatment in most unselected acromegalic patients. When administered to a group of poorly responsive patients, an increase in drug dose (60 mg im) and/or a shortening of the drug interval (10 days) seem to improve the GH/IGF-I response. Tolerability to SR lanreotide therapy is high. The use of a new sustained release formulation of somatostatin analog is clearly advantageous in improving patient compliance with medical treatment for acromegaly.

The effect of non-steroidal antiandrogen flutamide on luteinizing hormone pulsatile secretion in male-to-female transsexual subjects

We evaluated LH pulsatile patterns before and 4 weeks after the oral administration of flutamide (750 mg/day) in 9 male-to-female transsexuals (age range 17-28 yr) requesting gender reassignment. Flutamide was given to explore the feedback role of androgens on the LHRH-LH unit in LH pulsatility in transsexuals. Seven normal age-matched men served as a control group, without receiving flutamide, due to ethical considerations. LH pulsatility was evaluated on samples collected every 15 min for 360 min. FSH, PRL, cortisol, SHBG and sex steroids were evaluated on pooled samples. LH pulses were analyzed by the Santen and Bardin algorithm, slightly modified. No differences in FSH, PRL, total- or free-testosterone, estradiol and SHBG levels were noted between transsexuals and controls. Normal circadian cortisol decline was observed in all subjects. Mean LH levels (p < 0.05) and LH pulses (p < 0.01) were significantly lower in transsexuals. Flutamide induced an increase in mean LH and testosterone levels (p < 0.01). After flutamide administration there was an increase in LH pulse frequency (P < 0.01) and the frequency and amplitude of LH pulses in transsexuals were restored to levels observed in controls. No differences in FSH, PRL or estradiol levels were found after flutamide. These data suggest that a decrease in LH pulse frequency could be an endocrine marker in male-to-female transsexuals. An increase in endogenous androgen negative feed-back could be speculated in these subjects. However, normal testosterone levels indirectly suggest that a normal that a normal qualitative LH secretion is maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

Sumatriptan does not stimulate PRL and GH secretion in acromegaly

OBJECTIVE

Serotoninergic receptors are involved in the regulation of PRL and GH secretion. We studied the effects of sumatriptan, a new 5-HT1D receptor agonist, on PRL and GH secretion in active acromegaly.

EXPERIMENTAL DESIGN

After their informed consent, all subjects were submitted to sumatriptan or placebo administration in single blind and in a random order. The time interval between the tests was of 7 days.

ENVIRONMENT

We examined all patients in the morning, after 12 hours of fasting. All subjects were in recumbent position during the tests. Pulse rate and blood pressure were monitored during the test.

SUBJECTS

Eight acromegalics (42-65 years) and 10 age-matched (33-63 years) normal subjects.

PROTOCOL

Blood samples were taken after needle insertion kept patent by slow saline solution infusion. PRL and GH secretion were evaluated after sumatriptan (6 mg sc) and placebo. Blood samples were taken before (45, 15 and 0 minutes) and every 15 minutes for 2 hours after sumatriptan or placebo administration.

RESULTS

No significant changes in PRL secretion were observed after sumatriptan in both groups of subjects. A significant increase in GH levels after sumatriptan was observed in controls but not in acromegalics. An age-related negative trend in GH response to sumatriptan was observed in controls.

CONCLUSIONS

Our study indicated that 5-HT1D receptors are not involved in PRL and GH secretion in middle-aged acromegalics.

Treatment of acromegaly with octreotide: effectiveness and tolerability of its pulsatile administration by portable pump

This study was undertaken to evaluate effectiveness and tolerability of octreotide administered in active acromegaly by pulsatile means and compare these data with intermittent three-times-a-day therapy. We studied 13 acromegalics with active disease. All patients received octreotide subcutaneously administered in a pulsatile way using a portable pump delivering 25 micrograms every 120 minutes and in an intermittent way (100 micrograms three times daily) (TID). From pretreatment values (56.5 +/- 13.4 micrograms/L) the 24-h integrated mean GH levels (IC-GH) were significantly reduced both during pulsatile and TID octreotide administration (P < 0.01). IC-GH was significantly lower during pulsatile therapy (17.0 +/- 5.2 micrograms/L) than during TID (22.0 +/- 11.5 micrograms/L; P < 0.05). Before octreotide, IGF-I levels were 669.8 +/- 85.7 micrograms/L; during octreotide therapy they were reduced in 12/13 patients (TID 340.2 +/- 41.5 micrograms/L, pulsatile 338.1 +/- 55.3 micrograms/L; P < 0.01). A correlation between IC-GH and IGF-I levels was observed only during TID administration of octreotide (R = 0.652; P < 0.05). The 24-hour GH pattern fluctuated widely before the start of octreotide therapy. During TID administration, GH levels tended to rise again before the following octreotide injection; this did not occur during pulsatile therapy. Side effects were fewer during pulsatile (15%) than TID (31%) octreotide administration (NS). Asymptomatic gallstones appeared in 1 patient. In conclusion subcutaneous pulsatile octreotide administration in acromegalic patients by means of a small portable pump seems able to produce, a steadier control of GH-IGF-I hypersecretion and fewer side effects than TID administration at same dosage.

[Behavior of the pituitary-thyroid axis in acromegalic subjects during prolonged intermittent and pulsatile treatment with octreotide]

Octreotide, as well as endogenous somatostatin, inhibits GH and TSH secretion. The drug is employed in the medical therapy of acromegaly. We studied the effects of a long-term (1-120 months; median 12 months) therapy with octreotide (300 micrograms/day) given in 3-times intermittent s.c. administration or in pulsatile s.c. (25 micrograms/120 min) way, upon the pituitary-thyroid axis. Thirteen patients (11 with normal thyroid function, 1 with secondary hypothyroidism, 1 with toxic goiter) with active acromegaly were studied. In the euthyroid patients no significative variations in both TSH levels and thyroid hormones were found during octreotide therapy. In the non-euthyroid patients octreotide did not induce changes in the dosages of drugs acting to thyroid function. The 24-hour IC-TSH levels did not show any variation during octreotide. TSH response to TRH was reduced (P < 0.05) during octreotide therapy. No correlation among TSH, IGF-I and GH levels was observed. Long-term treatment of acromegaly with octreotide reduces TSH response to TRH but do not interfere with both 24-hour IC-TSH levels and thyroid function.