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C Giovannini

Publications and source records attributed to C Giovannini.

At least 55 records · Page 3Linked to original sources
PubMed1990

Beta-endorphin, insulin, ACTH and cortisol plasma levels during oral glucose tolerance test in obesity after weight loss.

In order to clarify a possible relationship between opioid peptides and glucose homeostasis in obesity we studied Beta-Endorphin (B-Ep), ACTH, cortisol and insulin plasma levels in response to an oral glucose tolerance test (OGTT) in 8 subjects after a hypocaloric diet for 90 days. We obtained through this treatment a weight loss superior to 30% of the initial weight excess (WE) compared with ideal body weight. Moreover, we compared the obtained results with our preliminary study that was performed with the same protocol but without caloric restriction. B-Ep was measured by RIA after silicic acid extraction and G75 Sephadex column chromatography. ACTH, insulin and cortisol were measured directly on plasma by an RIA method. Basal and during OGTT-induced levels of glucose, insulin, ACTH and cortisol decreased in comparison with the values obtained before diet. Conversely, B-Ep remained higher than normal both in the basal condition and during OGTT, and showed values consistently similar to those before diet. These data show that hyperinsulinemia is corrected by weight loss, while hyperbetaendorphinemia remains unchanged. Accordingly, it can be suggested that no direct relationship occurs between hyper-B-Ep-hyper-IRI in obesity. A further insight into the role of hyper-B-Ep in obesity is, thus, necessary, assuming as hypothesis that the increase in B-Ep may be a cause and not a corollary of the polymorphic aspects of obesity.

Adrenocorticotropic Hormone↗
PubMed1990

Modulation of non-N-methyl-D-aspartate receptors in cultured cerebellar granule cells.

Kainic acid (KA), quisqualic acid (QUIS), and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) stimulated D-[3H]aspartate release from cultured cerebellar granule cells in a concentration-dependent way. The EC50 values were 50 microM for KA (Gallo et al., 1987) and 20 microM for both QUIS and AMPA, but the efficacy of QUIS appeared to be greater than that of AMPA. The release of D-[3H]aspartate induced by KA, QUIS, and AMPA was blocked, in a dose-dependent way, by the new glutamate receptor antagonist 6-cyano-2,3-dihydroxy-7-nitroquinoxaline (CNQX); IC50 values were 0.7 microM in the case of AMPA (50 microM) and 1 microM in the case of KA (50 microM). AMPA (50-300 microM) inhibited the effect of 50 microM KA on D-[3H]aspartate release. At 300 microM AMPA, the effect of KA plus AMPA was not antagonized by the KA receptor antagonist kynurenic acid (KYN). In contrast, when KA was used at an ineffective concentration (10 microM), the addition of AMPA at concentrations below the EC50 value (10-20 microM) resulted in a synergistic effect on D-[3H]aspartate release. In this case, the evoked release of D-[3H]aspartate was sensitive to KYN. KA stimulated the formation of cyclic GMP, whereas QUIS, AMPA, and glutamate were ineffective. The accumulation of cyclic GMP elicited by KA (100 microM) was prevented not only by the antagonists CNQX (IC50 = 1.5 microM) and KYN (IC50 = 200 microM), but also by the agonists AMPA (IC50 = 50 microM) QUIS (IC50 = 3.5 microM), and glutamate (IC50 = 100 microM). We conclude that AMPA, like QUIS, may act as a partial agonist at KA receptors. Moreover, CNQX effectively antagonizes non-N-methyl-D-aspartate receptor-mediated responses in cultured cerebellar granule cells.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1990

[Neuroendocrine changes and affective disorders in patients with hyperphagic obesity].

Circulating levels of cortisol and beta-endorphin were evaluated in basal condition and following dexamethasone administration in 20 healthy subjects and in 60 subjects suffering from hyperphagic obesity. Moreover, mental tests were administered to these subjects in order to evaluate the affective state. Our data showed that in obese patients B-Ep plasma levels were significantly higher than those of the control group, while cortisol plasma levels were similar in the two groups. Dexamethasone administration decreased cortisol plasma levels in normal and obese subjects, while did not modify B-Ep plasma levels in obese subjects. However, after dexamethasone administration 16.6% of the obese subjects did not show a complete decrease of cortisol level. This group of subjects obtained the highest scores for depression and hypochondria to MMPI.

Adult↗
PubMed1990

[Plasma levels of beta-endorphin , ACTH and cortisol in obese patients subjected to several weight-loss treatments].

It is now well-known that the plasmatic levels of beta-endorphin (B-Ep) in subjects suffering from hyperphagie obesity during childhood, adolescence and adult age, are higher than those of normal weight standard-wright. The causes are still unknown. In obese subjects, there is also a dissociation between plasmatic levels of B-Ep and of ACTH, in spite of the common origin of Proopiomelanocortin (POMC). On the basis of these observations we studied the plasmatic levels of B-Ep, ACTH and cortisol, basal and after DXM, before and after the reduction of body weight. With the aim of evaluating pharmacological interference, the obese subjects were treated with diet alone or diet associated with an anorectic and serotoninergic drug (fenfluramin). The results have shown that after slimming, obtained with diet alone or with the help of the serotoninergic drug, the hyperendorphinemia persists both in basal conditions and after the DXM test. The verification of such behaviour in some psychiatric diseases supports our assumption of a link between hyperendorphinemia, behaviour alterations, hyperphagy and obesity.

Adrenocorticotropic Hormone↗
PubMed1989

Expression of excitatory amino acid receptors by cerebellar cells of the type-2 astrocyte cell lineage.

We have used postnatal rat cerebellar astrocyte-enriched cultures to study the excitatory amino acid receptors present on these cells. In the cultures used, type-2 astrocytes (recognized by the monoclonal antibodies A2B5 and LB1) selectively took up gamma-[3H]aminobutyric acid ([3H]GABA) and released it when incubated in the presence of micromolar concentrations of kainic and quisqualic acids. The releasing effect of kainic acid was concentration dependent in the range of 5-100 microM. Quisqualate was more effective than kainate in the lower concentration range but less effective at concentrations at which its releasing activity was maximal (approximately 50 microM). N-Methyl-D-aspartic acid and dihydrokainate (100 microM) did not stimulate [3H]GABA release from cultured astrocytes. L-Glutamic acid (20-100 microM) stimulated [3H]GABA release as effectively as kainate. The stimulatory effects of kainate and quisqualate on [3H]GABA release were completely Na+ dependent; that of kainate was also partially Ca2+ dependent. Kynurenic acid (50-200 microM) selectively antagonized the releasing effects of kainic acid and also that of L-glutamate; quisqualate was unaffected. Quisqualic acid inhibited the releasing effects of kainic acid when both agonists were used at equimolar concentrations (50 microM). D-[3H]aspartate was taken up by both type-1 and type-2 astrocytes, but only type-2 astrocytes released it in the presence of kainic acid. Excitatory amino acid receptors with a pharmacology similar to that of the receptors present in type-2 astrocytes were also expressed by the immature, bipotential progenitors of type-2 astrocytes and oligodendrocytes.

Animals↗
PubMed1989

Quisqualic acid modulates kainate responses in cultured cerebellar granule cells.

The activation of kainic acid and quisqualic acid receptors in cultured cerebellar granule cells stimulated the release of preaccumulated D-[3H]aspartate. The effect of kainate could be distinguished from that of quisqualate by its sensitivity to the antagonists kynurenic acid and 2,3-cis-piperidine dicarboxylic acid. At a concentration of kainic acid (50 microM) close to its half-maximal releasing effect, simultaneous addition of quisqualic acid (10-50 microM) resulted in a significant dose-dependent inhibition of the kainate-induced component of D-[3H]aspartate release, which was monitored by the progressive decrease in sensitivity of the evoked release to kynurenic acid. In contrast, when kainic acid was used at a subeffective concentration (10 microM), addition of low doses of quisqualate (2-5 microM) resulted in a synergistic effect on D-[3H]aspartate release. Under these conditions, the effect of the two agonists was sensitive to kynurenic acid. Kainic acid (50-100 microM) also caused a dose-dependent, kynurenic acid-sensitive accumulation of cyclic GMP (cGMP) in granule cell cultures. Quisqualic acid was, by itself, ineffective and prevented, in a dose-dependent manner, the kainate-induced cGMP formation (IC50 = 5 microM). Finally, the guanylate cyclase activator sodium nitroprusside greatly enhanced cGMP formation but had no effect on D-[3H]aspartate release. Together, these results demonstrate the existence of complex interactions between quisqualic and kainic acids and indicate that the effects of the two glutamate agonists on D-[3H]aspartate release and on cGMP accumulation are independent.

Animals↗
PubMed1988

Plasma B-endorphin resistance to dexamethasone suppression in obese patients.

Patients with simple exogenous obesity are characterized by increased B-endorphin (B-EP) plasma levels, despite normal ACTH and B-Lipotropin (B-LPH). To evaluate the origin of such an hyperendorphinemia, 42 obese patients were submitted to a short overnight dexamethasone suppression test (DST: 1 mg at 23:00 h). Blood samples were taken in basal conditions and 9, and 17 h after DST. The same procedure was applied in 12 healthy, normal weight volunteers. In further five patients, 0.5 mg per 4/die were given. B-EP was measured by radioimmunoassay (RIA) after silicic acid extraction and Sephadex G-75 column chromatography. ACTH and Cortisol were measured by direct IRMA and RIA, respectively. Basal B-EP levels of patients (24.2 +/- 16.5, fmol/ml, M +/- SD) were double than in normal weight controls (10.8 +/- 4.6), while ACTH and cortisol fell in the normal range. ACTH and cortisol were significantly reduced by DST in both patients and controls, while B-EP in patients did not. Cortisol, however, was not suppressed in 7 patients (16%). At 08:00, the suppression of B-EP in controls was 49.0 +/- 18.4%, while in obese patients it was only 21.2 +/- 38.8% (p less than 0.01). However, patients with weight excess below 50% normally suppressed B-EP (41.6 +/- 15.3%), while those with weight excess over 75% did not (11.3 +/- 47.5%). The doubling of dexamethasone intake does not lead to a suppression of plasma B-EP in these last patients. These data indicate the existence of neuroendocrine abnormalities in the hypothalamus-pituitary-adrenal axis of obese patients and suggest that their hyperendorphinemia originates outside the anterior pituitary.

Adolescent↗
PubMed1987

Plasma beta-endorphin in response to oral glucose tolerance test in obese patients.

In order to clarify the possible interaction between endogenous opioids and glucose homeostasis in obesity we studied Beta-Endorphin (B-Ep), ACTH, cortisol and insulin plasma levels in response to an oral glucose tolerance test (OGTT) in 8 females suffering from uncomplicated obesity and in 6 healthy volunteers of normal weight. Results were evaluated in terms of secretion areas subtracted from basal value. Basal glucose, insulin and B-Ep levels were significantly higher in the obese patients compared to controls, cortisol levels and ACTH were not statistically different between obese and normal subjects. During OGTT total areas of insulin secretion were significantly higher in the obese patients; cortisol, ACTH, B-Ep plasma levels did not change in controls, whereas obese patients showed a response to B-Ep which reached a peak at 60 minutes. The area of B-Ep response to OGTT in obese patients was significantly higher than in controls. On the basis of these results we may suggest that the opioid system belongs to the chain of neuroendocrine and metabolic events responsible for the origin and the growth of overweight. But the possibility exists that obesity itself can enhance the B-Ep secretion above all through overeating. In this regard it is to stress that glucose ingestion induces in obese patients, differently from normal subjects, insulin hypersecretion and the B-Ep secretion, possibly from gastro-enteric tract and/or pancreatic isles.

Adrenocorticotropic Hormone↗
PubMed1987

Glutamate receptor subtypes in cultured cerebellar neurons: modulation of glutamate and gamma-aminobutyric acid release.

Using cerebellar, neuron-enriched primary cultures, we have studied the glutamate receptor subtypes coupled to neurotransmitter amino acid release. Acute exposure of the cultures to micromolar concentrations of kainate and quisqualate stimulated D-[3H]aspartate release, whereas N-methyl-D-aspartate, as well as dihydrokainic acid, were ineffective. The effect of kainic acid was concentration dependent in the concentration range of 20-100 microM. Quisqualic acid was effective at lower concentrations, with maximal releasing activity at about 50 microM. Kainate and dihydrokainate (20-100 microM) inhibited the initial rate of D-[3H]aspartate uptake into cultured granule cells, whereas quisqualate and N-methyl-DL-aspartate were ineffective. D-[3H]Aspartate uptake into confluent cerebellar astrocyte cultures was not affected by kainic acid. The stimulatory effect of kainic acid on D-[3H]aspartate release was Na+ independent, and partly Ca2+ dependent; the effect of quisqualate was Na+ and Ca2+ independent. Kynurenic acid (50-200 microM) and, to a lesser extent, 2,3-cis-piperidine dicarboxylic acid (100-200 microM) antagonized the stimulatory effect of kainate but not that of quisqualate. Kainic and quisqualic acid (20-100 microM) also stimulated gamma-[3H]-aminobutyric acid release from cerebellar cultures, and kynurenic acid antagonized the effect of kainate but not that of quisqualate. In conclusion, kainic acid and quisqualic acid appear to activate two different excitatory amino acid receptor subtypes, both coupled to neurotransmitter amino acid release. Moreover, kainate inhibits D-[3H]aspartate neuronal uptake by interfering with the acidic amino acid high-affinity transport system.

Animals↗
PubMed1986

Hyperendorphinemia in obesity and relationships to affective state.

Eight obese patients (exceeding ideal body weight by 50% or more) with no endocrinological or metabolic disorders and 8 healthy, age-matched, normal-weight volunteers were submitted to an overnight short dexamethasone (DXM) suppression test and to a psychological assessment through various psychometric scales. Plasma B-Endorphin (B-EP), B-Lipotropin (B-LPH), ACTH and cortisol concentrations were evaluated in basal conditions, as well as 9 and 17 hours after late night administration of 1 mg DXM in both groups. All hormones were measured by radioimmunoassay, either directly in the plasma (ACTH and cortisol) or after silicic acid extraction and Sephadex G-75 column chromatography (B-LPH and B-EP). In obese patients, plasma B-EP levels in basal conditions were three times higher than in normal weight controls and remained unaltered by DXM suppression. ACTH and B-LPH, in contrast, were within the normal range and were significantly reduced by DXM. In 3 of the 8 patients, plasma cortisol concentrations at 17 hours post-DXM were greater than 50 ng/ml indicating an early escape from the suppression. Psychometric evaluations revealed a prevalence of depressive personality in obese patients. These data indicate an hypersecretion of B-EP in obese patients, which is only partially dependent on hypothalamic control.

Adrenocorticotropic Hormone↗
PubMed1984

[Influence of administration of pyridoxine on circadian rhythm of plasma ACTH, cortisol prolactin and somatotropin in normal subjects].

The influence of vitamin B6 in a dosage of 300 mg X 2 in 24 hrs, on circadian rhythm of plasmatic ACTH, cortisol, prolactin and somatotropin have been studied in 10 normal women. After vitamin B6 24 hrs pattern of ACTH and cortisol is unchanged; prolactin levels are slightly lower, in a statistically unsignificant proportion the night peak of growth hormone is higher in a statistically significant proportion (p. 0.05). The effect of vitamin B6 is likely to me mediated by dopaminergic receptors at hypothalamic level as previous studies by other Authors appear to prove.

Adrenocorticotropic Hormone↗
PubMed1983

[Behavior of circadian rhythm of ACTH and cortisol in 16 normal subjects after a balanced normocaloric diet and after a high protein diet (Cosinor mean method)].

In 16 normal subjects the circadian rhythm of ACTH has been studied during normal calories diet and after a 15 days period of high protein content diet (2 g/Kg body weight). The statistical study, according Cosinor method, has shown a significant increase of the mesor and of the amplitude, but has not shown any change of the ACTH and Cortisol rhythm, after hyperproteic diet. Data advise the increase of the tonic and fasic secretion of both hormones and shown the mantained acrophase. The action of the protein on the ACTH and Cortisol secretion does not seem related to mechanism like stress, neither to the probable mediation of intestinal like-ACTH messengers. On the contrary it seems related to a direct stimulus on the diencephalo-pituitary axis; it is possible that some amino-acids (tryptophan, arginine) act as a mediator, even if data concern just the effect of the over mentioned amino-acid in large doses.

Adrenocorticotropic Hormone↗