Oral glucose tolerance test unravels circulating miRNAs associated with insulin resistance in obese preschoolers.

BACKGROUND: Circulating microRNAs (miRNAs) may act as biomarkers of metabolic disturbances. OBJECTIVE: The aim of this study was to identify serum miRNAs signature of early insulin resistance in obese preschoolers. METHODS: Twelve obese children, aged 2-6 years, six insulin resistant (IR) and six controls were selected being age-matched, sex-matched and body mass index-matched. Profiling of 179 circulating miRNAs, known to be widely expressed in the bloodstream, was investigated by quantitative polymerase chain reaction at fasting and 120 min following a standard oral glucose tolerance test (OGTT). RESULTS: Twenty-one miRNAs were differentially regulated in IR obese preschoolers. miR-200c-3p, miR-190a and miR-95 were differently regulated both at fasting and 120 min after the OGTT. In controls, the fold changes of some miRNAs were correlated with Δglucose0-120 (miR-660, miR-26b-5p and miR-22-3p: p = 0.005 for all) and Δinsulin0-120 (miR-660 and miR-22-3p: p = 0.02 for both and miR-423-5p: p = 0.042). In IR patients, miR-1 fold changes were correlated with Δglucose0-120( r = -0.786; p = 0.036) and Δinsulin0-120( r = -0.821; p = 0.023). CONCLUSIONS: Our study identifies circulating miR-200c-3p, miR-190a and miR-95 as biomarkers of insulin resistance in obese preschoolers, being differentially regulated in IR patients both in fasting condition and after the OGTT. Expression of some circulating miRNAs seems reflecting glucose and insulin excursion following the OGTT differently in controls and IR obese preschoolers.

Comparative effects of 17beta-estradiol and phytoestrogens in the regulation of endometrial functions in the rodent uterus.

The present study aimed at improving our understanding of the effects of 17beta-estradiol and phytoestrogens on the uterine tissue, by evaluating tissue-specific modulation of molecules related to cell-cycle control and angiogenesis. Specifically, the uterine expression of Ki67, peroxisome proliferator-activated receptor gamma (PPARgamma), and vascular endothelial growth factor receptor-2 (VEGFR-2), was examined by immunohistochemical analysis. Ovariectomized (OVX) rats were treated with either the vehicle, a phytoestrogen- containing soy extract (SSE) (100 mg/kg/day pos), or 17beta-estradiol (0.5 mg/kg/day pos); a sham control group (SHAM) was also included in the study. At necropsy, uteri were weighed, collected, and subsequently processed for histopathology or immunohistochemistry. SSE-treated rats did not show any significant change either in the weight or in histological features of the uterus when compared to OVX controls; the epithelial expression of proliferation marker Ki67 was seen to be significantly reduced, in comparison to both SHAM and OVX rats. Conversely, 17beta-estradiol significantly increased uterine weight, induced hyperplasia in the majority of rats, and enhanced Ki67 epithelial expression. The regulation of PPARgamma expression, reduced after ovariectomy, was similar in SSE- and 17beta-estradiol-treated rats, showing a further significant decrease in stromal immunostaining, in comparison to OVX controls. VEGFR-2 epithelial immunostaining, slightly reduced following ovariectomy, was highly increased on 17beta-estradiol treatment, while following SSE, the pattern of staining observed was similar to that of OVX controls. Data from this study show that PPARgamma and VEGFR-2 represent additional targets by which sex steroid estrogen and plant-derived phytoestrogens may, at certain doses, differentially regulate endometrial functions.

Naloxone influence on the growth hormone, prolactin and thyrotropin response to thyrotropin releasing hormone in acromegalic patients.

In order to gain insight into the neuroendocrine mechanism underlying the paradoxical GH response to TRH in acromegalic patients, we have investigated the effect of an infusion of Naloxone (Nal, 1.6 mg/hr for two hours), on a TRH test performed both in responder (n = 9) and non-responder (n = 5) acromegalic patients. The response of GH, PRL and TSH to TRH injection were evaluated. NAL did not exert significant variations in the GH response, even if different patterns of GH response during NAL were observed in the group of TRH-responder patients. Similarly, TRH-induced PRL response was not significantly affected by the infusion of an opiate antagonist. On the contrary, a significant inhibition of the TSH response was observed in the group of TRH-responder patients (delta TSH after TRH 4.76 +/- 1.11 microU/ml, after NAL + TRH 2.81 +/- 0.99 microU/ml, p < 0.05). No significant effects were observed in the TRH non-responder patients (delta TSH after TRH 4.58 +/- 1.44 microU/ml, after NAL + TRH 6.26 +/- 3.27 microU/ml). The differences observed in the two groups of patients could be ascribed to a different endogenous somatostatinergic tone and could furnish a prognostic indication in acromegalic patients.

GH response to oral and intravenous glucose load in acromegalic patients.

The lack of inhibition of Growth Hormone (GH) levels after glucose load is considered a marker of inappropriate GH secretion in acromegaly. In order to investigate the physiopathology of this phenomenon, we have studied the GH variations after an oral glucose load (0.75 g/kg BW per os, OGTT) or intravenous glucose bolus (25 g i.v., IVGTT), in a group of 12 acromegalic patients, aged 20 +/- 69 yr (mean 48), 5 males and 7 females, with basal GH levels ranging from 11 to 76.2 ng/ml. The results indicate that only a group of acromegalic patients (group 1) had a partial GH inhibition after OGTT (mean decrease: 56.4 +/- 4.2%), but in no patients GH levels were influenced by intravenous administration of glucose. It is possible that in group 1 patients, the gastroenteric response could partially influence the GH secretion by the pituitary tumor, probably due to an increased peripheral somatostatin release. The dissociation of the GH response to OGTT and IVTT could indicate a supersensitivity to peripheral somatostatin, related to a deficiency in central somatostatinergic tone and therefore represent a more unfavourable prognostic sign.

Opioid dysregulation in anorexia nervosa: naloxone effects on preprandial and postprandial growth hormone response to growth hormone-releasing hormone.

Previously, we have shown that in the opposite extremes of nutritional status, obesity and anorexia nervosa (AN), growth hormone (GH) response to growth hormone-releasing hormone (GH-RH) is not inhibited by the ingestion of a normal 800-cal meal consumed at lunch time (1 PM), which is at variance with results in normal subjects. However, in obese patients the postprandial increase in GH response to GH-RH is inhibited by an infusion of naloxone (NAL). In this study we have tested anorectic patients, performing the following tests at 1 PM: GH-RH test (50 micrograms IV) or, in a different day session, NAL (1.6 mg/h, starting 30 minutes before GH-RH) + GH-RH test (50 micrograms IV). The tests were performed in the following three different experimental conditions: (1) short-term fasting studies (lasting from breakfast), (2) long-term fasting studies (from midnight of the day before) and (3) postprandial studies (after a standard meal consumed 1 hour before the test). In AN, the GH response to GH-RH was not influenced by NAL infusion at 1 PM, in both short- and long-term fasting studies (short-term fasting: peak values after GH-RH alone, 26.5 +/- 6.5 ng/mL, during NAL, 28.0 +/- 3.3 ng/mL; long-term fasting: peak values after GH-RH alone, 32.2 +/- 6.8 ng/mL, during NAL, 30.6 +/- 4.0 ng/mL). A partial NAL-inhibitory effect was instead observed in postprandial studies, as evidenced by the calculation of areas under the curve ([AUCs] 1,662.1 +/- 90.0 after GH-RH alone v 1,090.5 +/- 245.4 ng/mL/h during NAL).(ABSTRACT TRUNCATED AT 250 WORDS)

[Reevaluation of the I-dopa test in acromegaly: anatomo-clinical and prognostic correlations]. / Rivalutazione del test alla I-dopa nell'acromegalia: correlazioni anatomo-cliniche e prognostiche.

It is known that in acromegalic patients the GH secretion exhibits a pattern of response to various stimuli that differs from that observed in normal subjects. We have evaluated the paradoxical GH response to 1-Dopa in acromegaly, in order to clarify the relationships between this datum and the tumour size, the basal GH secretion, the GH response to TRH and the long-term prognosis. MATERIALS AND METHODS. 34 acromegalic patients, 12 men and 22 women, aged 35-70 yr, participated in this study. They were divided in 4 classes, according to Hardy's classification of pituitary neoplasias: (1) intrasellar microadenomas, < 10 mm (n = 8); (2) intrasellar macroadenomas, > 10 mm (n = 14); 3) adenomas with local expansion (n = 9); (4) adenomas with extrasellar expansion (n = 3). All patients underwent a 1-Dopa-test; 18 of them underwent a TRH-test. Basal postoperative GH and basal pre- and postoperative PRL levels were also determined. RESULTS. The basal preoperative GH values in all patients ranged between 16 and 278 ng/ml. 22 patients showed a paradoxical response to 1-Dopa, 12 were non-responders. The following results were observed in the different classes: [table: see text] Moreover, 10 subjects (56%) were TRH-responders (9 of them were also 1-Dopa-responders, 1 was non-responder) and 8 were TRH non responders (6 were 1-Dopa non-responders, 2 were 1-Dopa responders). Basal postoperative GH values were > 5 in 17 1-Dopa responders and in 9 non responders. Basal preoperative PRL levels were > 25 ng/ml in 7 1-Dopa responders and in 2 non responders. After surgery, basal PRL became normal in 5 responder patients. DISCUSSION. In a previous work we have correlated the paradoxical GH response to TRH with tumour size and GH levels, observing a higher percentage of paradoxical response in patients in class I and II and, postoperatively, lower GH levels in preoperative TRH responders. So, we have underlined the good prognostic feature of a preoperative paradoxical response. In this paper we have evaluated the paradoxical GH response to 1-Dopa in the different Hardy's classes and compared it with the GH levels and the GH response to TRH. The results show that a paradoxical response can be observed more frequently in small (class I) adenomas than in greater size ones, and in presence of lower GH basal levels. Moreover, a concordance between 1-Dopa and TRH tests can be observed. CONCLUSIONS. The results clearly indicate that the responses to dynamic GH tests should be evaluated considering the anatomic characteristics of the neoplasias. It could be suggested that the paradoxical response can be expressed only when hypothalamus-pituitary interactions are intact.

Pyridostigmine effects on TSH response to TRH in adult and children obese subjects.

Thyrotropin releasing hormone (TRH) administration is known to induce a greater TSH response in normal subjects than in obese subjects. In obesity even GH and PRL response to various stimuli are blunted, presumably because of an augmented somatostatinergic tone in obese subjects. Further studies have shown that pyridostigmine (Pyr), an acetylcholinesterase inhibitor, is capable of augmenting GH in obesity by means of somatostatin inhibition. In order to evaluate the possible interference of an increased somatostatinergic tone on TSH secretion, we studied the TSH response to a TRH bolus in 5 obese children with or without a pyr pretreatment. Similarly, we tested a group of 10 obese adult subjects, with TRH alone or TRH plus pyr administration, 30 min or 60 min before TRH. All subjects had a body weight of 30-50% greater than I.B.W. Our data show that a pretreatment with pyr, 60 min before TRH administration, significantly augments the TSH response in adult obese subjects but not in children; the modality of pyr administration seems to be crucial to evidenciate such an alteration since the pyr pretreatment is not effective when administered 30 min before TRH. The absence of this pyr effect in obese children induces to hypothesize that somatostatinergic tone is differentially modulated in children vs adult obese subjects.

Opioid-dopaminergic interactions in primary empty sella.

Previous studies have indicated different abnormalities of PRL secretion in patients with primary empty sella (PES). Since it is known that endogenous opiates and dopamine interact in modulating PRL secretion, we have studied the effect of an opiate receptor blockade (with Naloxone, NAL, 1.6 mg/h as a continuous infusion) on anterior pituitary hormones and on PRL responsiveness to metoclopramide (MCP), in 10 premenopausal normoprolactinemic patients with PES, studied in follicular phase, in order to investigate neurotransmitter abnormalities present in such a syndrome. NAL failed to significantly affect LH and FSH basal levels; on the contrary, slight but significant increases in PRL and GH secretion were observed. NAL partially blunted the PRL responsiveness to the dopaminergic blockade, which was very marked when tested after MCP alone. These data confirm that the modulation of anterior pituitary hormone secretion is different in PES patients, when compared with normal subjects. The infusion of NAL induced a "paradoxical" increase in hormones (PRL and GH) which are normally stimulated by endogenous opiates; but, on the other side, it blocked the marked PRL responsiveness to the dopaminergic blockade, which is characteristic of PES syndrome. This phenomenon seems to indicate that the relationships between dopaminergic and opiatergic neurons could be modified by the neuroanatomic alteration which is present in this complex syndrome.

Influence of pyridostigmine on growth hormone (GH) response to GH-releasing hormone pre- and postprandially in normal and obese subjects.

The effect of pyridostigmine (PYR), an inhibitor of acetylcholinesterase, on the GH response to GH-releasing hormone (GHRH) before and after a meal was studied in 14 normal subjects (8 females and 6 males) and 21 obese subjects (13 females and 8 males). In normal subjects tested in a fasting state, PYR was capable of stimulating GH secretion and increasing the GH response to GHRH. These effects were not apparent after food, suggesting a reduction in cholinergic hypothalamic activity. In obese subjects tested in a fasting state, PYR was ineffective when administered alone. On the contrary, it was able to increase the GH response to GHRH. After food, the augmenting effect of PYR on the GH response to GHRH was not observed, whereas a delayed inhibition of the GH response was found after PYR plus GHRH treatment. Our findings support the hypothesis that cholinergic hypothalamic activity plays a pivotal role in impaired GH regulation and the altered sensitivity of GH secretion to metabolic fuels in obese subjects.

Effects of progesterone administration on follicle-stimulating hormone and prolactin release in estrogen treated eugonadal adult men.

In order to investigate the modulatory effect of steroids on FSH secretion in vivo, we studied 16 human males, aged 51-81 years, affected by prostatic carcinoma. They were given estradiol or E2 plus progesterone (P), added at different times during E2 treatment. Daily blood samples were collected in order to determine LH, FSH, and PRL levels; moreover, blood samples were collected at 2 h intervals for 12 h on the day of P administration. We observed the expected biphasic effect on LH secretion, whereas daily basal FSH levels, during E2 treatment, decreased gradually and progressively from the first day until the end of the study. FSH levels exhibited, after P administration, wide fluctuations, with peak levels observed from 2 to 6 h after P in 4 of 6 patients studied (at 72 h during E2 treatment). A clear trend toward FSH increase was also observed in 3 out of 5 patients in whom P was administrated 96 h after starting E2 administration. In this case, FSH increases were delayed, becoming evident between 8th and 10th h after P injection. Finally, during E2 administration basal PRL levels showed a progressive increase, which was significant in all three groups. In conclusion, these data confirm the biphasic effects of estrogen administration on LH secretion in eugonadal adult human males; while estrogens alone showed an inhibitory effect on FSH secretion, the addition of P induced also a positive action, resulting in a clear FSH peak in some patients tested. The time course of E2 and P administration seems to be critical for the hormone response pattern.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of 2 different genetic markers for the detection of frameshift and missense mutagens in A. nidulans.

21 chemicals, known to induce missense and/or frameshift mutations directly, were assayed for their ability to forward mutate a haploid strain of A. nidulans. 2 genetic markers for forward mutations were used, namely 8-azaguanine resistance and induction of meth A1 suppressors. Missense mutagens were usually active when tested with the plate-incorporation technique, whereas frameshift agents were ineffective; some of these, on the other hand, turned out to be positive when tested with a liquid-test procedure. The 2 genetic markers used showed a similar sensitivity (with only 2 exceptions) in detecting the chemical mutagens assayed.