Search PubMed⌕ Search

Biomedical subjects

A Volpe

Publications and source records attributed to A Volpe.

At least 235 records · Page 13Linked to original sources
PubMed1986

Effects of sodium valproate and diazepam on beta-endorphin, beta-lipotropin and cortisol secretion induced by hypoglycemic stress in humans.

Evidence that gamma-aminobutyric acid (GABA) and benzodiazepine receptors play a role in the inhibition of ACTH-cortisol secretion in humans has until now been drawn only from data indicating that sodium valproate, a GABA mimetic, and diazepam, a benzodiazepine, decrease hypothalamus-pituitary-adrenal (HPA) axis secretion in patients affected by pathological hypersecretion of the axis. Therefore, the present study investigated the effects, in the same healthy subjects, of sodium valproate or diazepam, on both basal and stress-stimulated concentrations of beta-endorphin (beta-EP), beta-lipotropin (beta-LPH) and cortisol. A single maximal dose of sodium valproate (400 mg) or diazepam (10 mg) did not significantly modify basal concentrations of beta-EP, beta-LPH and cortisol. On the other hand, in the same subjects, pretreatment with sodium valproate (20 mg X 3) or diazepam (10 mg X 2) blocked the increases in these hormones produced by hypoglycemic stress in all patients tested (p less than 0.01 vs. placebo at 45, 60 and 90 min after insulin injection), without affecting the decrease in blood glucose levels. The present data show that sodium valproate and diazepam inhibit stress-induced beta-EP, beta-LPH and cortisol secretion in humans, suggesting that endogenous GABA and benzodiazepine receptors participate in physiological mechanisms regulating the activity of the HPA axis.

Adult↗
PubMed1986

Reduction of beta-endorphin levels in the amniotic fluid of heroin addicts.

Plasma levels of beta-endorphin and beta-lipotropin in 18 heroin addicts were found to be similar to those in pregnant control subjects at all stages of gestation. In contrast, amniotic fluid levels of beta-endorphin were significantly lower in heroin abusers than in controls in both the first and second trimesters. Amniotic fluid levels of beta-lipotropin were reduced only in the second trimester. At term, when the patients were almost drug free, the amniotic fluid levels of both peptides were in the control range. These data support the existence of a specific control mechanism for amniotic fluid levels of beta-endorphin and beta-lipotropin, independent of the maternal pituitary, and show that exogenous opiates interfere with it negatively.

Amniotic Fluid↗
PubMed1985

Short-term effects of ovariectomy: the opioid control of LH secretion in fertile climacteric and postmenopausal women.

The aim of this study was to evaluate the activity of opiate receptors involved in the regulation of LH secretion in relationship to ovariectomy. Menstruating fertile (n = 5) and climacteric (n = 7) patients and postmenopausal (n = 5) women who underwent therapeutical bilateral ovariectomy were studied in the first week postsurgery and LH plasma levels were evaluated after naloxone (4 mg in bolus plus 4 mg infusion/90 min), LHRH (10 micrograms + 10 micrograms iv) and saline administration. Two groups of fertile (n = 6) and postmenopausal (n = 6) subjects were studied as controls. Since the LH responsiveness to naloxone was impaired in climacteric patients after ovariectomy, the test was repeated in 5 of them after 1 and 6 months of estrogen-gestagen treatment (conjugated estradiol + noretisterone acetate), showing a significant increase in all patients in both cases. In four subjects treated with only gestagen, naloxone was still unable to significantly modify LH plasma levels. These results indicate that ovariectomy affects the activity of opiate receptors, resulting in the first week postsurgery LH rise inversely related to basal LH levels. Furthermore, these results indicate that one or six cycles of estrogen-gestagen treatment in ovariectomized patients similarly induces a restoration of the opiate receptors neuroendocrine activity.

Adult↗
PubMed1985

Hypothalamus-pituitary-adrenal axis of heroin addicts.

The hypothalamus-pituitary-adrenal axis of heroin addicts was investigated by evaluating plasma cortisol levels throughout the day in 37 heroin abusers (HA), 17 of whom showed detectable morphine levels, indicating heroin administration in the previous hours and in 12 controls. All HA showed lower cortisol levels in basal condition (100.7 +/- 61.7 ng/ml, M +/- S.D.) compared to the control group (159.7 +/- 40.6, P less than 0.05). Moreover all HA (65.1 +/- 28.9%), and in particular those taking heroin during the study (39.1 +/- 41.4%), show a reduced cortisol decrease in the evening, which was significantly lower than in controls (85.3 +/- 10.1%; P less than 0.01). As far as the acute effects of opiates are concerned morphine (0.1 mg/kg) significantly reduced plasma cortisol levels within 60 min in a group of 8 healthy subjects. The same pattern was displayed by only 3/8 HA whose morphine levels were higher than 1 ng/ml, i.e. in those reaching the highest plasma morphine concentrations. These data indicate that chronic opiate abuse leads to a hypoadrenalism which could be the result of morphine-induced changes at the hypothalamic level.

Adolescent↗
PubMed1985

Impairment of opioid control of luteinizing hormone secretion in menstrual disorders.

With the aim of examining central opioid influences on the control of luteinizing hormone (LH) secretion, we evaluated the LH response to naloxone, an opioid receptor antagonist, in patients affected by normo-, hyper-, and hypogonadotropic amenorrhea, polycystic ovarian disease and hyperprolactinemia. The results indicate that opioid influences are altered in well-defined pathologic conditions (hyperprolactinemia, obesity), in addition to being modified by gonadal steroids.

Adenoma↗
PubMed1985

Recombination-deficient Streptococcus sanguis.

A UV-sensitive derivative was obtained from Streptococcus sanguis Challis. The organism could be transformed with a number of small streptococcal plasmids at frequencies equal to, or 1 logarithm below, the transformation frequencies for the parent organism. However, transformation with chromosomal DNA was greatly impaired in the UV-sensitive derivative.

Methyl Methanesulfonate↗
PubMed1985

Lack of beta-endorphin plasma level rise in oxytocin-induced labor.

beta-Endorphin (beta-EP), beta-lipotropin (beta-LPH) and cortisol plasma levels were measured during labor in 18 pregnant women. In 7 cases labor progressed spontaneously and in 11 cases oxytocin (5 mIU/min) was administered to stimulate uterine contractions. In control and oxytocin-treated subjects hourly blood samples were taken until delivery. In spontaneous labor all three hormones showed a progressive and significant increase until parturition. In oxytocin-treated patients, however, both beta-EP and beta-LPH remained constant until parturition. Cortisol levels in oxytocin-treated patients presented a significant increase but reached values significantly lower than in control patients. These results indicate that women with uterine hypocontractility during labor requiring oxytocin showed no rise in their plasma beta-EP and beta-LPH and a blunted cortisol rise during oxytocin administration.

Adult↗
PubMed1985

Impairment of adrenergic-induced proopiomelanocortin-related peptide release in heroin addicts.

The effects of iv stimulation with clonidine on plasma levels of beta-lipotropin (beta-LPH), beta-endorphin (beta-EP), cortisol, growth hormone (GH) and adrenocorticotrophic hormone (ACTH) were tested in a group of 10 healthy volunteers and in 8 heroin abusers. Hormones were measured either by direct radioimmunoassay (RIA) (GH, cortisol) or after plasma extraction and Sephadex G-75 column chromatography (beta-LPH and beta-EP) or by immunoradiometric assay (IRMA) (ACTH). Plasma levels of GH increased in a similar fashion in the two groups. In the controls, clonidine induced release of beta-LPH and beta-EP after 30 min (from 8.9 +/- 1.0 to 19.1 +/- 4.6 fmol/ml, P less than 0.01 and from 8.1 +/- 0.6 to 17.9 +/- 4.6, P less than 0.01) and of ACTH after 60 min (from 12.1 +/- 1.8 to 18.1 +/- 1.8, P less than 0.05) while in addicts beta-EP but not beta-LPH showed a significant increase (from 8.5 +/- 0.7 to 19.8 +/- 4.2, P less than 0.05), 90 min after the injection. In heroin addicts, plasma cortisol levels decreased continuously after clonidine stimulation while in controls they showed a biphasic pattern, decreasing until the 60th min (from 135.2 +/- 30.4 ng/ml to 74.0 +/- 13.3, P less than 0.05) and regaining basal levels 1 h later (122.0 +/- 24.8, P less than 0.05 vs 60th min value). These data demonstrate the existence in human beings of noradrenergic control of proopiomelanocortin (POMC)-related peptides and indicate that chronic opiate abuse greatly interferes with this control. Clonidine-induced release of plasma beta-EP may be of importance with regard to its therapeutic effects in detoxification.

Adolescent↗
PubMed1985

Opioid peptides of the pituitary and hypothalamus: changes in pregnant and lactating rats.

Immunoreactive (Ir) beta-endorphin concentrations were determined in plasma, anterior pituitary (AP), neurointermediate pituitary lobe (NIL) and mediobasal hypothalamus (MBH) of pregnant (12-14 and 18-20 days) and fertile control rats, during labour and lactation. Immunoreactive Met-enkephalin concentrations were also evaluated in the MBH. Concentrations of Ir beta-endorphin in plasma, AP and NIL of rats during early and late pregnancy were significantly higher than in controls, the plasma and AP contents showing an increasing pattern in the second half of gestation. During labour, Ir beta-endorphin concentrations in plasma and AP reached the highest values, whereas those in NIl remained unchanged. Lactating rats showed Ir beta-endorphin concentrations in NIL and plasma in a range similar to that found in pregnant rats, resulting in concentrations in the AP not significantly different from those of nonpregnant controls. Immunoreactive beta-endorphin and Ir Met-enkephalin concentrations in MBH of pregnant rats were almost twice as high as in controls, rising markedly during labour; during lactation levels were in the same range as in non-pregnant controls. These results indicate that pregnancy and labour are characterized by high plasma, pituitary and hypothalamic concentrations of Ir-beta-endorphin as well as by high hypothalamic Ir Met-enkephalin levels, and that Ir beta-endorphin concentrations vary differently during pregnancy, lactation and labour in the two pituitary lobes, supporting the existence of different control mechanisms in the AP and NIL.

Animals↗
PubMed1985

Estrogen changes as a critical factor in modulation of central opioid tonus: possible correlations with post-menopausal migraine.

The effects exerted by ovarian steroids on the modulation of opioid activity were investigated in post-menopausal migraine sufferers and in healthy controls. In order to evaluate central opioid tonus, plasma LH rise after naloxone injection was measured, bearing in mind the tonic inhibition of endogenous opioid on hypothalamic LH-RH. There was no response of plasma LH to naloxone in post-menopausal women or in patients submitted to ovariectomy in fertile life. When the subjects underwent a sequential estrogens + progestagens therapy, such a response was noted from the first month of treatment; progestagens alone were ineffective. The same phenomena were also evident in post-menopausal migraine sufferers. These data indicate that ovarian steroids modulate the activity of opiate receptors in both healthy women and migraine sufferers. Interestingly, replacement therapies through ovarian steroids restored the activity of central opioid tonus in patients affected by migraine.

Adult↗
PubMed1984

Increase of proopiomelanocortin-related peptides during subjective menopausal flushes.

The present study reports the plasma levels of gonadotropins (luteinizing hormone, follicle-stimulating hormone), proopiomelanocortin-related peptides (adrenocorticotropic hormone, beta-endorphin, and beta-lipotropin), and cortisol in eight menopausal women experiencing frequent hot flushes. beta-Endorphin and beta-lipotropin levels were measured by radioimmunoassay after extraction and Sephadex G-75 column chromatography. Plasma levels of adrenocorticotropic hormone (after extraction), luteinizing hormone, follicle-stimulating hormone, and cortisol were measured by specific radioimmunoassay. All hormone levels showed a prompt and significant rise on occurrence of hot flushes (18 total recordings), remained high for 15 minutes, and decreased to basal levels 35 minutes later. The evaluation of the behavior pattern of single hormone levels revealed a more pronounced increase of proopiomelanocortin-related peptides and cortisol than of gonadotropins (p less than 0.01).

Adrenocorticotropic Hormone↗
PubMed1984

Lack of correlation between amniotic fluid and maternal plasma contents of beta-endorphin, beta-lipotropin, and adrenocorticotropic hormone in normal and pathologic pregnancies.

Reported are the concentrations of beta-endorphin, beta-lipotropin, and adrenocorticotropic hormone (ACTH) in the amniotic fluid and plasma of 40 healthy pregnant women at different stages of gestation. Moreover, the amniotic fluid levels of the three peptides were evaluated in 20 other pregnant women affected by different pathologic conditions (Cooley's disease, gestosis, diabetes, placental insufficiency, etc.). A silicic acid extraction procedure was performed on the samples. Each extract was subjected to Sephadex G-75 column chromatography, and the two fractions corresponding to beta-lipotropin and beta-endorphin were collected, freeze-dried, and assayed by two specific radioimmunoassays. Levels of ACTH were measured by radioimmunoassay directly on the extracts. Levels of beta-endorphin in amniotic fluid showed the highest values in the first trimester (173 +/- 30 fmol/ml, mean +/- SEM) but were significantly decreased in the second (75.2 +/- 14) and third trimesters (14.3 +/- 1.8). An inverse trend characterized plasma levels of beta-endorphin, which showed a progressive increase from the first trimester to term (10.4 +/- 11.1). Amniotic fluid levels of beta-lipotropin remained stable during the first (48.6 +/- 6.3) and second (54.6 +/- 11.1) trimesters, but decreased significantly in the third trimester (17.9 +/- 2.3). The plasma concentrations of beta-lipotropin showed the highest levels in the first trimester (10.9 +/- 0.9), and decreased significantly at term (8.9 +/- 1.3). Last, amniotic fluid levels of ACTH decreased from 55.3 +/- 4.75 fmol/ml in the first trimester to 12.5 +/- 1.16 in the second trimester, and rose again in the third trimester to 34.4 +/- 6.6 fmol/ml. Plasma levels of ACTH were characterized in the first two trimesters by values twice those recorded for nonpregnant women, and decreased at term to 8.9 +/- 1.4 fmol/ml. In the pregnant patients with fetuses affected by Cooley's disease (second trimester) and in those with edema-proteinuria-hypertension (EPH) gestosis (third trimester), amniotic fluid levels of beta-endorphin, beta-lipotropin, and ACTH were in the same range as those in healthy pregnant women.

Adrenocorticotropic Hormone↗
PubMed1984

Serotoninergic agonists increase plasma levels of beta-endorphin and beta-lipotropin in humans.

A pharmacological approach was used to investigate the serotoninergic control of plasma levels on beta-endorphin (beta-EP) and beta-lipotropin (beta-LPH) in humans. Acute administration of L5-OH-triptophan, the physiologic precursor of serotonin (SE), induced a significant rise in plasma beta-EP and beta-LPH levels both when injected iv (20 and 40 mg) (four normal men) and when administered orally (200 and 400 mg) (seven normal men) (P less than 0.01 vs. placebo). The iv route of administration induced a prompt (mean peak values after 150 min) dose-dependent increase in beta-EP and beta-LPH levels. The responses evoked by oral administration (mean peak values after 130 and 240 min) were not dose dependent. Fluoxetine (15 and 30 mg orally) a blocker of SE reuptake, induced a significant dose-related rise in plasma beta-EP and beta-LPH levels in a group of seven normal men (P less than 0.01) (mean peak values after 150 min). Pretreatment with methysergide, a SE receptor antagonist (3 X 2.8 mg orally, five men), did not induce any significant changes in plasma beta-EP and beta-LPH levels, but blocked the increase in the two hormones evoked by L5-OH-triptophan (40 mg iv). Plasma cortisol levels changed similarly to those of beta-EP and beta-LPH in all the experiments, indicating that putative serotoninergic drugs exert a positive role on the various corticotropin-releasing hormone-mediated secretions.

5-Hydroxytryptophan↗
PubMed1984

Impaired circadian rhythmicity of beta-lipotrophin, beta-endorphin and ACTH in heroin addicts.

The circadian rhythm of plasma proopiocortin-related peptides was studied in 15 heroin addicts and in 6 sex- and age-matched controls. ACTH, beta-lipotrophin, (beta-LPH), beta-endorphin (beta-EP) and cortisol were measured by RIA either directly (cortisol), or after plasma extraction (ACTH) and Sephadex G-75 gel chromatography (beta-LPH and beta-EP) every 4 h from 8 a.m. to 8 p.m. and again at 8 a.m. the next morning. The means of the two 8 a.m. measurements of beta-LPH (2.67 +/- 0.34 fmol/ml, mean +/- SE), ACTH (2.74 +/- 0.71) and cortisol (218 +/- 31 pmol/ml) levels in heroin addicts were significantly lower than those in controls (6.28 +/- 0.61, 10.1 +/- 0.74 and 364 +/- 27, respectively, P less than 0.01) while beta-EP concentrations in heroin addicts (5.1 +/- 0.6) were similar to those of healthy volunteers (6.44 +/- 0.56). In controls, all three peptides and cortisol show a circadian rhythm of secretion, the lowest values being in the evening and the highest ones in the morning. Heroin addicts partially lack this phenomenon showing constant levels of the three proopiocortin-related peptides throughout the day, with a slight but significant decrease of plasma cortisol. In the 7 subjects who took heroin throughout the study, no systematic changes were observed in the three proopiocortin-related peptides, while it seems that this group of addicts shows a cortisol decrease in the evening to a lesser extent than subjects receiving methadone maintenance only.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

The renin-aldosterone system and electrolyte balance during tocolytic therapy.

The effects of short and long-term tocolytic therapy, with salbutamol on renin activity, aldosterone levels, sodium and potassium concentration in urine, blood, and red blood cells in 44 pregnant women were studied. No significant changes were observed in renin activity and aldosterone levels between the 1st and 5th days of i.v. or p.o. therapy and in 24-h sodium urinary excretion. Serum potassium levels significantly decreased by the 2nd and 4th h from start of i.v. infusion of salbutamol, returning to preinfusion levels within 24-36 h, whereas no concomitant increase in red cell potassium levels was detected. Urinary potassium excretion showed significant decrease within 24 h from start of i.v. therapy, returning to control levels after 48 h. No change in sodium concentration in blood and red blood cells was observed.

Administration, Oral↗
PubMed1983

Drug addiction during pregnancy.

On the basis of current literature and their own experience, the authors discuss (1) the major complications possible in pregnant drug addicts, (2) whether the complications can be attributed to deficient prenatal care or to effects of drug abuse, and (3) the best prenatal care of drug-addicted mothers.

Birth Weight↗