Protein kinase Cε regulates proliferation and cell sensitivity to TGF-1ß of CD4+ T lymphocytes: implications for Hashimoto thyroiditis.

We have studied the functional role of protein kinase Cε (PKCε) in the control of human CD4(+) T cell proliferation and in their response to TGF-1ß. We demonstrate that PKCε sustains CD4(+) T cell proliferation triggered in vitro by CD3 stimulation. Transient knockdown of PKCε expression decreases IL-2R chain transcription, and consequently cell surface expression levels of CD25. PKCε silencing in CD4 T cells potentiates the inhibitory effects of TGF-1ß, whereas in contrast, the forced expression of PKCε virtually abrogates the inhibitory effects of TGF-1ß. Being that PKCε is therefore implicated in the response of CD4 T cells to both CD3-mediated proliferative stimuli and TGF-1ß antiproliferative signals, we studied it in Hashimoto thyroiditis (HT), a pathology characterized by abnormal lymphocyte proliferation and activation. When we analyzed CD4 T cells from HT patients, we found a significant increase of PKCε expression, accounting for their enhanced survival, proliferation, and decreased sensitivity to TGF-1ß. The increased expression of PKCε in CD4(+) T cells of HT patients, which is described for the first time, to our knowledge, in this article, viewed in the perspective of the physiological role of PKCε in normal Th lymphocytes, adds knowledge to the molecular pathophysiology of HT and creates potentially new pharmacological targets for the therapy of this disease.

Glucoreceptors located in the brain mediate NPY release induced by hypoglycemia in normal men.

The NPY secretory pattern after an insulin tolerance test (ITT) (0.15 IU/kg body weight) was evaluated in 8 normal men. They were infused with normal saline (control test), glucose or fructose. Insulin-induced hypoglycemia produced a significant increment in serum NPY in the control test. The infusion of fructose was unable to change the NPY secretory pattern during insulin-induced hypoglycemia. In contrast, the NPY increase during ITT was completely abolished when the concomitant infusion of glucose prevented insulin-induced hypoglycemia. These results exclude a direct role of hyperinsulinemia in the mechanism underlying the stimulation of NPY secretion during ITT. Furthermore, since glucose but not fructose crosses the blood-brain-barrier (BBB), the NPY increase during ITT appears to be generated by low glucose concentrations at the level of glucosensitive areas located inside the brain.

Naloxone decreases the inhibitory effect of alprazolam on the release of adrenocorticotropin/cortisol induced by physical exercise in man.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: • Alprazolam (ALP), a benzodiazepine activating GABAergic receptors, is involved in ACTH secretion. WHAT THIS STUDY ADDS: • This study demonstrates a partial opioid influence in the inhibitory effect of ALP on the release of ACTH/cortisol during physical exercise. AIMS: To establish the possible involvement of alprazolam (ALP) and/or opiates in the mechanism underlying the ACTH/cortisol response to physical exercise. METHODS: Tests were carried out under basal conditions (exercise control test), exercise plus ALP (50 µg at time -90 min), naloxone (10 mg at time 0) or ALP plus naloxone. Plasma ACTH and serum cortisol concentrations were evaluated in blood samples taken before, during and after the bicycle ergometer tests. RESULTS: ACTH and cortisol concentrations rose significantly after physical exercise. Maximum peak at time 15 min (P ≤ 0.01 vs. baseline) for ACTH and at time 30 min (P ≤ 0.01 vs. baseline) for cortisol. In the presence of naloxone, the ACTH and cortisol responses were significantly increased (maximum peak at time 20 min, P ≤ 0.02 vs. control test for ACTH, and at time 30 min (P ≤ 0.01 vs. baseline) for cortisol) whereas they were abolished by ALP. When ALP and naloxone were given together, the inhibitory effect of ALP was partial. CONCLUSIONS: These data demonstrate an inhibitory effect of ALP in the regulation of the ACTH/cortisol response to physical exercise in man and suggest that GABAergic receptor activating benzodiazepines and opioids interact in the neuroendocrine secretion of ACTH/cortisol.

Naloxone decreases the inhibitory effect of somatostatin on GH release induced by cigarette smoking in man.

To establish whether somatostatin (SRIH) exerts its inhibitory effect on the nicotine-induced release of GH by interacting with an opioid pathway, normal volunteers were treated with naloxone during (2 no-filter) cigarettes smoking and with SRIH. Nicotine significantly increased serum GH levels about 3.5 fold. Naloxone alone did not change GH rise induced by cigarette smoking. The stimulatory effect of GH by nicotine was completely blocked by SRIH. In the presence of both SRIH and naloxone, GH levels rose 1.5 fold in response to nicotine. Since naloxone only partially reversed the inhibiting action of SRIH, only a partial involvement of opioid peptides in SRIH action might be supposed. Alternatively, SRIH and naloxone-sensitive opiates might produce this inhibiting effect on GH rise in response to cigarette smoking through independent pathways.

Oxytocin does not modify GH, ACTH, cortisol and prolactin responses to Ghrelin in normal men.

BACKGROUND: In order to test the possible effect of Oxytocin (OT) on Ghrelin-stimulated GH, PRL, ACTH and cortisol, ten healthy normal men were studied. TESTS: Ghrelin (0.2 µg/kg body weight (BW)) as an iv bolus; Ghrelin plus OT (2 IU as bolus plus 0.07 IU/min administered for 90 min). RESULTS: The administration of OT did not change GH, PRL, ACTH and cortisol release induced by Ghrelin. CONCLUSIONS: The data suggests that in humans OT did not modulate the GH, PRL, ACTH and cortisol response to Ghrelin.

Increased arginine-vasopressin response to hypertonic stimulation and upright posture in idiopathic hyperprolactinemia.

To evaluate the possible influence of idiopathic hyperprolactinemia on the arginine-vasopressin (AVP) response to osmotic and pressure-volumetric stimuli, 14 idiopathic hyperprolactinemic women and 13 normoprolactinemic women were studied during a hypertonic saline infusion test (0.51M NaCl infusion for 2h) and an orthostatic test (standing upright and maintaining an orthostatic position for 20min). In both experimental conditions, the AVP response was significantly higher in women with idiopathic hyperprolactinemia than in normal normoprolactinemic women. These results indicate that in women hyperprolactinemia influences the AVP response to hyperosmotic and hypovolemic stimuli.

Inhibitory effect of dexamethasone on arginine-vasopressin release induced by physical exercise in man.

To establish whether glucocorticoids inhibit the arginine-vasopressin (AVP) response to physical exercise, 10 healthy men underwent bicycle ergometer tests until exhaustion (exercise control test, exercise plus dexamethasone [2 or 4 mg in an intravenous bolus]). Physiological and biochemical variables were similar in all tests. Pretreatment with dexamethasone (2 or 4 mg) partially but significantly decreased the AVP response induced by physical exercise. Our results demonstrate a partial inhibition induced by glucocorticoids of AVP neurosecretion during cycle ergometer tests.

Effect of naloxone on the inhibitory effect of melatonin on the release of arginine-vasopressin induced by physical exercise in man.

This study was performed in order to establish whether endogenous opioids play a role in the inhibitory effect of melatonin on arginine-vasopressin (AVP) response to physical exercise. Seven healthy men underwent four bicycle ergometer tests until exhaustion [exercise control test, exercise plus naloxone (2mg injected plus 5mg infused intravenously), exercise plus melatonin (6mg), exercise plus melatonin plus naloxone]. Plasma AVP concentrations, non endocrine physiological parameters (NEPP) and biochemical parameters were evaluated during all tests. NEPP and biochemical values had a similar pattern during all tests. Physical exercise significantly increased the AVP levels. The pre-treatment with melatonin inhibited the AVP response to physical exercise. In contrast, naloxone had no effect on AVP rise during exercise, when given alone, whereas it abolished the negative effect of melatonin on AVP response to physical exercise. Our data indicate that naloxone-sensitive endogenous opiates mediate the inhibitory modulation exerted by melatonin on the AVP response to physical exercise.

Effect of physical training on age-related reduction of GH secretion during exercise in normally cycling women.

OBJECTIVE: To evaluate whether prolonged physical activity (25 km/week running for 8 years) modifies GH decline. DESIGN: The GH response to maximal exercise on bicycle-ergometer was tested in younger (26-30 years) and older (42-46 years) healthy women. Each age group included 2 subgroups of 10 sedentary and 10 runners, which were compared. The workload was increased at 3 min intervals from time 0 until exhaustion. Subjects with a low maximal capacity (as established in a preliminary test) pedalled for 3-4 min against no workload at the beginning of the test, so that exercises lasted about 15 min in all individuals. RESULTS: At exhaustion, heart rate and systolic pressure were significantly higher in sedentary than in trained subjects, whereas V(O(2)max), blood glucose and plasma lactate levels were similar in all groups. Exercise induced similar GH responses in younger sedentary and exercise-trained subjects and in older exercise-trained subjects, with mean peak levels 7.5 times higher than baseline. In contrast, in older sedentary women peak GH level was only 4.4 times higher than baseline and was significantly lower than in the other groups. CONCLUSION: These data suggest that in women prolonged physical training exerts protective effects against age-dependent decline in GH secretion.

A case report of Sheehan's syndrome with acute onset, hyponatremia and severe anemia.

Sheehan's syndrome is a well-known cause of panhypopituitarism secondary to pituitary apoplexy, that generally occurs after an intra- or postpartum bleeding episode characterized by severe hypertension or hemorrhagic shock. The diagnosis can be difficult and is often formulated after some years from the syndrome occurrence. We report the case of a woman with an early diagnosis of early-onset Sheehan's syndrome associated with severe hyponatremia following dystocic childbirth complicated by postpartum hemorrhage.

Oxytocin inhibits the stimulatory effect of ghrelin on circulating neuropeptide Y levels in humans.

UNLABELLED: Oxytocin (OT) effect on ghrelin-stimulated neuropeptide Y (NPY) secretion was evaluated in 12 normal men. TESTS: ghrelin (1 microg/kg B.W. as an intravenous bolus); OT (2 mIU/min infusion); ghrelin plus OT; normal saline. Plasma NPY did not change during saline or OT infusions, whereas it showed a significant 29% increase vs baseline at 15 min after ghrelin injection. When OT was present, ghrelin-induced NPY increment was completely abolished. Results show that oxytocin modulates the NPY response to ghrelin, whereas it is unable to produce direct inhibitions of basal circulating NPY levels.

Effects of moderate ethanol drinking on the GH and cortisol responses to physical exercise.

OBJECTIVE: To evaluate the effects of moderate amounts of ethanol on the GH and cortisol responses to physical exercise. METHODS: Ten normal men underwent three bicycle ergometer tests. Test were carried out in basal conditions (control test) or after drinking 0.5 or 0.75 g/kg BW ethanol. Tests lasted 15 min in all subjects; the workload was increased at 3 min intervals from time 0 until exhaustion. Non-endocrine physiological parameters (NEPP), such as heart rate, blood pressure, ventilation, frequency of breathing, tidal volume, oxygen consumption, carbon oxide production and respiratory exchange ratio were measured from time 0 until exhaustion. Serum GH and cortisol levels were evaluated in blood samples taken at 5-10 min intervals over a 50 min period from time 0. RESULTS: Neither basal values, nor exercise-induced changes in NEPP were altered by ethanol drinking. Both GH and cortisol levels significantly rose during the exercise control test. The hormonal responses did not change after 0.5 g/kg BW ethanol, whereas they significantly decreased after 0.75 g/kg BW ethanol. CONCLUSIONS: Modification of the GH and cortisol responses to exercise represents an "endocrine window" of the effects that even moderate ethanol drinking produces in the CNS. The data show that 0.75 g/kg BW ethanol is the minimal amount producing significant inhibitory effects on the GH and cortisol responses to physical exercise. In view of the important roles played by GH and cortisol during physical activity, even moderate ethanol drinking must be avoided before sport.

Adrenocorticotropic hormone/cortisol response to physical exercise in abstinent alcoholic patients.

BACKGROUND: Alterations in the hypothalamic-pituitary-adrenal (HPA) axis in alcoholic patients have been reported in various experimental conditions. METHODS: To establish whether alcoholism affects the HPA axis activation during physical exercise, 10 recent abstinent alcoholic patients (age range: 33-45 years; duration of alcohol dependence: range 4-6 years) were tested by exercising on a bicycle ergometer. Ten age-matched healthy nonalcoholic men participated as controls. The workload was gradually increased at 3-minute intervals until exhaustion and lasted about 15 minutes for all subjects. Alcoholic patients were tested at 3 time points, at 4, 6, and 8 weeks after alcohol withdrawal, whereas controls were tested only once. Main outcome measurements were circulating levels of adrenocorticotropic hormone (ACTH) and cortisol and physiological variables during physical exercise [heart rate, blood pressure, ventilation, frequency of breathing, tidal volume, oxygen consumption (VO2), carbon oxide production (VCO2), and respiratory exchange ratio (R)]. RESULTS: Similar basal and exercise-induced changes in physiological variables were observed in controls and alcoholic patients in all tests. Basal levels of ACTH and cortisol were similar in all tests performed on alcoholic patients and on normal controls. In normal subjects, exercise induced a significant increase in plasma ACTH and serum cortisol levels, with peak levels at 20 minutes for ACTH (84% higher than baseline) and at 30 minutes for cortisol (70% higher than baseline). After 4 weeks of abstinence, slight but not significant ACTH/cortisol responses to physical exercise were observed in alcoholic patients (mean peaks were 10 and 18% higher than baseline, respectively, for ACTH and cortisol). By contrast, when the exercise test was repeated after 6 weeks abstinence, ACTH/cortisol levels rose significantly versus baseline (mean peak levels of ACTH and cortisol were 48 and 38% higher than baseline, respectively, for ACTH and cortisol). However, the hormonal responses were significantly lower than in the normal controls. At 8 weeks of abstinence, ACTH/cortisol responses were significantly higher than 2 weeks previously, and were not distinguishable from the increments observed in the normal controls (76 and 68% higher than baseline, respectively, for ACTH and cortisol). CONCLUSIONS: In concurrence with previous reports showing alterations of the HPA axis in the central nervous system in alcohol-dependent subjects, these data show a defect of the neuroendocrine mechanism(s) underlying the ACTH/cortisol response to physical exercise for at least a month after alcohol withdrawal, with reconstitution of a normal hormonal response at 8 weeks.

Effects of ghrelin on circulating neuropeptide Y levels in humans.

OBJECTIVE: Ghrelin is a 28 amino-acid peptide with a strong GH-releasing activity and a complex role in regulation of appetite, fuel utilization, body weight and composition. Neuropeptide Y (NPY) is a well-known stimulator of pathways favouring food intake and energy storage. Recently, studies in rodents suggested a possible mediation of ghrelin action by NPY. In contrast, until now no evidence of ghrelin-NPY interaction in humans has been provided. In the present study, we examined whether ghrelin influences NPY secretion in normal men. SUBJECTS AND DESIGN: Twelve healthy normal men (aged 24-35 years; body mass index (BMI) 22.3+/-0.93 kg/m2) were tested twice at 08.00 AM on two different days, in random order at weekly intervals, after an overnight fast and rest in bed. An intravenous bolus of 1 microg/kg body weight ghrelin (esperimental test) or an equal amount of normal saline (control test) was injected at time 0. Blood was taken before and over 90 minutes after injections, and was used for the measurement of plasma NPY levels. RESULTS: Plasma levels of NPY slightly, but significantly rose in response to ghrelin, with a mean peak level at 15 min after injection, whereas no significant change was observed after saline administration. MAIN FINDING: Our results show a significant enhancement of plasma NPY levels under ghrelin stimulation. CONCLUSIONS: To our knowledge, this is the first demonstration of a ghrelin-NPY interaction in humans, which may suggest a possible mediation of ghrelin action by NPY in humans.

Different plasma neuropeptide Y concentrations in women athletes with and without menstrual cyclicity.

The circulating levels of leptin and neuropeptide Y, which are both involved in the control of feeding and reproduction, were measured in amenorrheic and normal cycling highly trained women athletes, and in normal cycling sedentary controls. Leptin showed similar low values in all athletes, whereas neuropeptide Y levels were significantly higher in normal cycling athletes than in the other groups, suggesting the possibility of a protective role of neuropeptide Y in the maintenance of the menstrual cycle in highly trained athletes.

Is steroid therapy needed in the treatment of destructive thyrotoxicosis induced by alpha-interferon in chronic hepatitis C?

OBJECTIVE: Treatment with interferon (IFN) of patients affected by chronic hepatitis C (CH-C) may produce alterations in thyroid function, such as hypothyroidism, Graves'-like hyperthyroidism and destructive thyrotoxicosis (DT). IFN-induced DT is characterized by suppressed serum TSH levels, normal or elevated FT4 and FT3 concentrations, with the presence or absence of thyroid peroxidase antibodies and antithyroglobulin antibodies, the absence of thyroid receptor antibodies and radioactive iodine uptake suppressed or <5%. DESIGN: IFN-induced DT is a mild clinical disease, because thyroid-destructive processes last for a short time and involve a small portion of the gland. At present, the therapeutic approach in DT suggests IFN withdrawal and 1-2 months of methylprednisolone treatment. METHODS: In consideration of possible untoward side effects of steroid treatment in patients with CH-C, we studied two groups of patients with CH-C who developed DT after treatments with various preparations of recombinant IFN (with or without ribavirin). Patients sequentially entered the study during a 4-year period, at the time of DT diagnosis, when IFN therapy was discontinued. The first 12 subjects (group A) were treated with 8-16 mg/day methylprednisolone for 30-40 days after IFN withdrawal; in the following 15 patients (group B), IFN withdrawal was not followed by any additional treatment. All patients underwent clinical and laboratory controls of thyroid function at 1, 2, 3 and 6 months after DT diagnosis. RESULTS: The results showed restoration of euthyroidism in both group A and group B patients at 6 months after DT diagnosis, regardless of steroid treatment. CONCLUSIONS: The simple withdrawal of IFN therapy in patients with CH-C, who had developed DT, appears to be effective in the treatment of the thyroid disease. This therapeutic approach should be preferred in order to avoid possible undesired side effects of steroid therapy in patients with CH-C.

Adrenocorticotropin/cortisol and arginine-vasopressin secretory patterns in response to ghrelin in normal men.

This study was performed in order to establish the secretory patterns and the possible relationships between the adrenocorticotropin (ACTH)/cortisol and arginine vasopressin (AVP) responses in normal men to the systemic administration of ghrelin, an endogenous ligand for the growth hormone secretagogue receptor. For this purpose, a bolus of 1 microg/kg ghrelin was injected intravenously in 9 normal men. AVP, ACTH and cortisol significantly rose in response to ghrelin injection; however, in all subjects the AVP rise preceded the ACTH/cortisol responses. In fact, the mean peak levels of AVP, ACTH and cortisol after ghrelin injection were observed at 15, 30 and 45 min, respectively. When peak AVP responses to ghrelin were considered together with ACTH and cortisol peak levels, highly significant positive correlations were observed (AVP and ACTH, r = 0.94, p < 0.001; AVP and cortisol, r = 0.92, p < 0.001). In conclusion, this study shows that the AVP response to ghrelin precedes the concomitant ACTH/cortisol rise and that these hormonal responses are highly positively correlated. These observations support the hypothesis that AVP mediates ghrelin-induced ACTH secretion in normal men.

Inhibition of growth hormone secretion in mild primary hyperparathyroidism.

INTRODUCTION: Impairment in growth hormone (GH) secretion has been reported to occur in primary hyperparathyroidism (PHP) with strikingly elevated (>150 pg/ml) plasma PTH and free Ca levels. Patients with these characteristics are relatively few, whereas the great majority of patients with biochemically diagnosed PHP are asymptomatic and show borderline or slightly elevated plasma PTH and Ca levels. We wondered whether also patients in these latter conditions show a defective GH secretory pattern. METHODS: In order to answer this question, 8 female subjects (mean age +/- SE: 44 +/- 1.3 years) were selected at the time of a checkup examination from a larger population of persons in fairly good clinical condition. Inclusion criteria were plasma PTH values slightly above the normal range (up to 50% higher than the maximum limit) with free Ca levels in the upper normal range or slightly higher (experimental group). Normal values in our laboratory are ionized calcium: 1.22-1.42 mmol/ml and plasma PTH: 12-72 pg/ml. A group of 15 age-matched healthy women with plasma PTH and Ca levels in the middle normal range and significantly lower than values found in the experimental group was also selected and used as control. Experimental and control groups were tested with arginine [0.5 mg/kg body weight (BW)] infused intravenously over 30 min and arginine plus GH-releasing hormone (GHRH; 1 microg/kg BW in an intravenous bolus injection). The GH responses to these challenging stimulations were compared between groups. RESULTS: Basal serum GH values were similar in all subjects. Both arginine and arginine plus GHRH induced a significant GH rise in both groups; however, the GH responses were significantly lower in the experimental than in the control group. Mean GH peak was 27.7 and 14.6 times higher than baseline after arginine and 57.5 and 26.6 times higher than baseline after arginine plus GHRH in the control and experimental group, respectively. No significant correlation was observed between PTH or Ca levels and the GH responses to challenging stimuli in any group. CONCLUSION: These data show that impairment in GH secretion is associated with slightly elevated levels of PTH in the presence of serum Ca values in the upper normal range. GH responses to stimulations were reduced by about 50% in our hyperparathyroid subjects. A long-time duration of this relatively small decline of GH secretory activity may be supposed to contribute to age-related catabolic processes in a large number of patients with mild primary hyperparathyroidism.

Glucoreceptors located inside the blood-brain barrier mediate hypoglycemia-induced LH inhibition in man.

OBJECTIVE: To establish the role of hyperinsulinemia and hypoglycemia during the insulin tolerance test (ITT) in the regulation of luteinizing hormone (LH) secretion and the location with respect to the blood-brain barrier (BBB) of the glucosensitive areas controlling LH release. METHODS: The LH-secretory pattern during an ITT (0.15 IU/kg body weight) was evaluated in 8 normal men during infusion with normal saline (control test), glucose or fructose. RESULTS: lnsulin-induced hypoglycemia produced a significant decrement in serum LH levels in the control test, but not when the concomitant infusion of glucose prevented hypoglycemia. Fructose infusion did not change LH decrease during ITT. CONCLUSIONS: These data exclude a direct role of hyperinsulinemia in the mechanism underlying the inhibition of LH secretion during ITT. Furthermore, since glucose but not fructose crosses the BBB, the LH decrease during ITT appears to be generated by hypoglycemia at the level of glucosensitive areas located inside the BBB.

The nocturnal serum thyrotropin surge is inhibited in patients with adrenal incidentaloma.

BACKGROUND: Alterations in hypothalamic-pituitary function have been described in patients with incidentally discovered adrenal adenomas and have been attributed to their subtle hypercortisolemic status. METHODS: To establish whether the central control of the hypothalamic-pituitary-thyroid axis is altered in these endocrine conditions, the nocturnal (10:30 PM-2:00 AM) serum thyroid-stimulating hormone (TSH) surge (measured by dividing the difference between nighttime and morning TSH values by the morning TSH value and then multiplying by 100), the TSH response to thyrotropin-releasing hormone (200 microg as an intravenous bolus) and serum free thyroid hormone levels were evaluated in patients with adrenal incidentaloma (experimental group) and in normal controls (control group). Urinary free cortisol concentrations were also measured. RESULTS: The nocturnal TSH surge was observed in the normal controls, whereas it was inhibited in the patients of the experimental group. Serum free triiodothyronine levels were similar in the two groups, whereas the TSH response to thyrotropin-releasing hormone was significantly lower in the experimental than in the control group. Urinary free cortisol levels were significantly higher in the experimental group. CONCLUSION: These data indicate that even conditions of slight glucocorticoid excess may exert inhibitory effects on TSH secretion, which suggests the presence of a slight central hypothyroidism in patients with adrenal incidentaloma.