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Biomedical subjects

A Volpe

Publications and source records attributed to A Volpe.

At least 217 records · Page 12Linked to original sources
PubMed1989

Effect of oral contraceptives or dexamethasone on plasma beta-endorphin during the menstrual cycle.

Several studies have showed a significant increase of plasma beta-endorphin levels during the periovulatory days of the menstrual cycle. The aim of the present study was to investigate the origin of the periovulatory changes of plasma beta-endorphin, trying to discriminate between a possible ovarian and/or pituitary origin. Daily plasma beta-endorphin, luteinizing hormone (LH), and cortisol levels were measured from the 8th to the 20th day of the menstrual cycle in healthy normal-cycling women (10 cases) before and during dexamethasone (DEX; 6 cases) or estroprogestinic treatment with monophasic (5 cases) or triphasic (5 cases) pill. In the control menstrual cycle, during the preovulatory days, a significant increase of plasma beta-endorphin was found. While oral contraceptives abolished the midcycle increase of plasma beta-endorphin, the periovulatory plasma beta-endorphin peak was present during DEX treatment. Plasma cortisol levels did not show any significant change throughout the control menstrual cycle, while they were significantly lowered by the DEX administration and significantly increased during estroprogestinic treatment. These results suggest that the increase of plasma beta-endorphin during the periovulatory days is related to the ovulatory function, and suggest a possible ovarian origin.

Adolescent↗
PubMed1989

Plasma and amniotic fluid immunoreactive neuropeptide-Y level changes during pregnancy, labor, and at parturition.

This study was designed to determine the presence of and possible changes in plasma and amniotic fluid immunoreactive neuropeptide-Y (irNPY) levels in pregnant women during gestation and at parturition. We studied 127 healthy pregnant and 12 nonpregnant women. The peptide was extracted from plasma or amniotic fluid with a propanolformic acid mixture and measured by RIA. The mean plasma irNPY concentration in 15 pregnant women during the first trimester of gestation was 129 +/- 12 (+/- SE) pmol/L, compared to 40 +/- 8 pmol/L in nonpregnant women (p less than 0.01). The mean values were 144 +/- 13 and 156 +/- 24 pmol/L, respectively, in 15 pregnant women during the second trimester and 33 women during the third trimester. These values did not differ from that during the first trimester. Amniotic fluid irNPY levels were similar to those in plasma and did not vary among the 3 groups of women studied during the various trimesters of gestation. During labor, plasma irNPY levels progressively increased, reaching the highest levels at the most advanced stages of cervical dilatation (greater than 8 cm, 351 +/- 38 pmol/L) and at the time of vaginal delivery (416 +/- 73 pmol/L). Plasma irNPY levels then decreased significantly 2 h after vaginal delivery. The amniotic fluid irNPY levels in women during the early or late stages of labor were similar. Moreover, plasma and amniotic fluid irNPY levels at the time of elective cesarean section also were similar. These results indicate that pregnant women have high plasma and amniotic fluid irNPY levels and that the stress of labor results in a further increase in plasma levels, suggesting a possible role of NPY in human pregnancy and parturition.

Adult↗
PubMed1989

Glucocorticoids but not vasopressin or oxytocin inhibit luteinizing hormone secretion in patients with psychogenic amenorrhea.

Activation of the hypothalamus-pituitary-adrenal (HPA) axis is suggested to play a role in the stress-related inhibition of LH secretion. The aim of our study was to investigate the effects of vasopressin and oxytocin, which are increased in pituitary portal plasma in response to stress, and of glucocorticoids, the final product of HPA activation during stress, on basal plasma LH levels and on pituitary LH response to the GnRH test in amenorrheic (n = 33) and fertile (n = 13) women. Plasma LH levels were evaluated by radioimmunoassay in 2 different experimental conditions: 1. Basal secretion; 2. The GnRH test (10 micrograms + 10 micrograms after a 120-minute interval). These 2 evaluations were done in the presence of both placebo and a pharmacological dose of desmopressin (an analogue of vasopressin) (16.6 ngr/minute), oxytocin (0.2 ngr/minute) or hydrocortisone (4.1 mg/minute). None of these drugs modified basal plasma LH levels either in amenorrheic patients or in controls. Hydrocortisone inhibited the GnRH-induced LH increase in amenorrheic women. These data suggest that the glucocorticoids might play a role in LH secretion and indicate a possible participation of the HPA axis in the impairment of the hypothalamus-pituitary-gonadal axis in women with psychogenic amenorrhea.

Adult↗
PubMed1989

Ovarian response to combined growth hormone-gonadotropin treatment in patients resistant to induction of superovulation.

The efficacy of combined growth hormone (GH)-gonadotropin treatment has been studied in patients previously resistant to sole gonadotropins for induction of superovulation. Eleven patients (aged 26-41) with a mechanical cause of infertility were treated. All were given the same dosage of gonadotropins as in previous cancelled cycles (6-17 ampules/cycle of menofollitropin; 34-80 ampules/cycle of human menopausal gonadotropin) plus a standard dosage of GH (0.1 IU per kg body weight, daily). Younger patients (n = 6, age 26-36) showed a considerable improvement of ovarian response in terms of number of mature follicles aspirated by laparoscopy (performed on day 11-13). Older patients (n = 5, age 39-41) did not show any significant improvement of ovarian response with combined treatment and all had their stimulatory cycle cancelled. Follicular fluid (FF) levels of GH, 17 beta-estradiol (E2) and progesterone (P) were significantly higher in the group of younger GH-treated patients (n = 53 follicles) than in 4 controls treated with gonadotropins only (n = 32 follicles). FF insulin-like growth factor-I (IGF-I) did not significantly differ between the two groups. A significant positive linear correlation has been found between FF GH and IGF-I in the GH-treated group. In conclusion, GH-gonadotropin combined treatment considerably improves ovarian response in protocols for superovulation induction in younger gonadotropin-resistant patients. A local action of GH and IGF-I in the ovaries may be hypothesized.

Adult↗
PubMed1988

Steroid replacement treatment increases beta-endorphin and beta-lipotropin plasma levels in postmenopausal women.

The present study shows the effects of two different steroid replacement therapies, with conjugated estrogens or with a new synthetic steroid derivative, ORG OD14, on plasma beta-endorphin (beta-EP) and beta-lipotropin (beta-LPH) levels in postmenopausal subjects. Blood samples were collected before treatment and after 1, 2 and 4 months of treatment; a third group of patients was treated with placebo. After 2 months of treatment both groups of patients who underwent steroid supplementation showed circulating levels of beta-EP and beta-LPH higher than basal levels. ORG OD14 treatment increased beta-EP and beta-LPH levels more than conjugated estrogens at the 2nd month of therapy. No further change was found after 4 months. The two drugs were effective in reducing hot flushes and improving physical and psychological symptoms. These data indicate that sex steroids are able to increase beta-EP and beta-LPH secretion in postmenopausal women, with a concomitant relief of climacteric symptoms.

Adult↗
PubMed1988

Evidences for a dopamine-regulated peripheral source of circulating beta-endorphin.

Circulating beta-endorphin (beta EP) and beta-lipotropin (beta LPH) concentrations increase after the administration of acetylcholine or serotonin agonist drugs. In this study we examined the effect of dopamine receptor agonists and/or antagonists on plasma beta EP, beta LPH, cortisol, and PRL levels in normal subjects. Neither direct dopamine (DA) agonist drugs, DA (1 microgram/kg min for 120 min), bromocriptine (2.5 mg po), L-dopa (500 mg po) or an indirect DA agonist, nomifensine (200 mg po), significantly altered plasma beta EP and beta LPH levels. The administration of metoclopramide, a DA antagonist (10 mg iv), significantly increased plasma beta EP, beta LPH, PRL, and cortisol levels. This effect was completely reversed by pretreatment with L-dopa (500 mg po) and only partially antagonized by DA infusion. Domperidone (10 mg iv), a DA antagonist which does not cross the blood brain barrier, increased only plasma beta EP levels, an effect inhibited both by L-dopa and DA. After dexamethasone (2 mg/day for 2 days) domperidone still increased plasma beta EP and PRL levels. The concomitant increase of beta EP, beta LPH, and cortisol after metoclopramide suggests that endogenous DA inhibits the secretion of proopiomelanocortin-related peptides. Moreover, since domperidone increases only beta EP and this effect is not altered by dexamethasone, there may be a corticotropin-releasing hormone-independent source of circulating beta EP in humans, which is inhibited by DA.

Acetylcholine↗
PubMed1988

Impairment of the opioidergic control of luteinizing hormone secretion in Turner's syndrome: lack of effect of gonadal steroid therapy.

We studied the activity of endogenous opioid peptides in regulating LH secretion in patients with Turner's syndrome. To do so, we determined the LH secretory response to opiate receptor blockade by naloxone (0.08 mg/kg BW, iv) in 17 patients (age range, 9-23 yr). Eight patients were untreated (3 of whom had had spontaneous menarche), and 9 patients were taking ethinyl estradiol/medroxyprogesterone acetate treatment (5 of these patients were also studied before treatment). In addition, the plasma LH responses to GnRH (50 micrograms, iv) and placebo were determined in the patients as well as in 13 age-matched normal girls (6 prepubertal and 7 pubertal). Naloxone did not increase plasma LH levels in the amenorrheic untreated and treated patients with Turner's syndrome. However, in the 3 patients who had had spontaneous menarche and in normal pubertal girls naloxone increased plasma LH levels. GnRH was effective to the same extent in the patients and normal subjects. These results indicate that in patients with Turner's syndrome the opioidergic inhibition of LH secretion is impaired and is not restored by gonadal steroid replacement therapy. Moreover, the normal plasma LH responses to naloxone in the spontaneously menstruating patients with Turner's syndrome indicate both the clinical variability of this syndrome and the participation of endogenous opioid peptides in the regulation of normal menstrual function.

Adolescent↗
PubMed1987

Effects of Org OD 14 on pituitary and peripheral beta-endorphin in castrated rats and post-menopausal women.

The aim of the first part of this study was to evaluate the effects of a new synthetic steroid (7 alpha,17 alpha)-17-hydroxy-7-methyl-19-norpregn-5(10)-en-20-yn-3-one (Org OD 14), on anterior pituitary (AP) and neurointermediate pituitary lobe (NIL) contents and on circulating levels of beta-endorphin (beta-EP) in rats. Three weeks after ovariectomy, groups of 9 rats were treated with either Org OD 14 (2 or 10 micrograms/day/rat for 14 days) or a placebo. In addition, 2 groups of ovariectomized rats were also treated with oestradiol benzoate (EB) (2 or 10 micrograms/day/rat for 14 days) to compare the effectiveness of the new steroid with that of a classical oestrogenic substance. beta-Ep concentrations were measured in plasma and in AP and NIL extracts by means of double-antibody radioimmunoassay (RIA), employing a specific anti-camel beta-EP (C-terminal fragment). Both doses of Org OD 14 induced a significant dose-related increase in plasma and pituitary lobe beta-EP concentrations as compared with the results on placebo treatment. By comparison, EB was active only at a dose of 10 micrograms/day. Despite the common stimulatory effects of EB and Org OD 14 on pituitary beta-EP, these findings suggest that the two steroids have different modes of action. The second part of the study investigated the changes in beta-EP and beta-lipotrophin (beta-LPH) plasma levels in a group of post-menopausal women treated for 6 months with Org OD 14 (2.5 mg/day) in comparison with the levels in a placebo-treated group. The clinical efficacy of Org OD 14 treatment in post-menopausal symptoms was confirmed, as well as its lack of or only transient effect on plasma lipids and lipoproteins. beta-EP and beta-LPH plasma levels were significantly higher in the Org OD 14-treated group than in the placebo group as from the second month until the end of the observation period.

Adult↗
PubMed1987

Proopiomelanocortin-related peptides and methionine enkephalin in human follicular fluid: changes during the menstrual cycle.

Several studies indicate the presence of different pituitary hormones or neuropeptides in ovarian follicular fluid from various species. Recently our group showed that the ovarian follicular fluid of health women contains two of the endogenous opioid peptides, beta-endorphin and methionine enkephalin, in concentrations that are tenfold to twentyfold higher than in circulating plasma. The presence of immunoreactive beta-lipotropin was also shown. The aim of the present study was to evaluate whether adrenocorticotropic hormone, which in pituitary cells is synthesized from proopiomelanocortin such as beta-endorphin and beta-lipotropin, is also present in follicular fluid and the possible changes of proopiomelanocortin-related peptides during the menstrual cycle. Concentrations of beta-endorphin, methionine enkephalin, adrenocorticotropic hormone, and beta-lipotropin were measured in 60 healthy menstruating women at different periods of the menstrual cycle (20 during the follicular, 22 in the preovulatory days, and 18 during the luteal phase). Thirteen women participated in an in vitro fertilization program and thus received clomiphene citrate (100 mg/day from the fifth to the ninth day) plus 5000 IU human chorionic gonadotropin before starting the program. All samples were collected at laparoscopy under general anesthesia. In another eight patients fluid was collected from follicular cysts. Peptides were extracted on octadodecasilyl silica columns with 80% methanol in 0.5 mol/L acetic acid. The identity of follicular fluid beta-endorphin, methionine enkephalin, adrenocorticotropic hormone, and beta-lipotropin and standard peptides was demonstrated with high-pressure liquid chromatography. Peptide concentrations were measured in extracts by radioimmunoassays either directly by (methionine enkephalin and adrenocorticotropic hormone) or after (beta-endorphin and beta-lipotropin) gel filtration on Sephadex G-75. The concentrations of methionine enkephalin, adrenocorticotropic hormone, and beta-lipotropin were similar in the different periods of the cycle. Conversely, beta-endorphin concentrations were significantly higher in preovulatory days than in the other periods; no differences were evident between spontaneous and stimulated cycles. These results indicate that proopiomelanocortin-related peptides are present in the follicular fluid and that beta-endorphin concentrations change during the menstrual cycle, with the highest values occurring in the preovulatory follicle.

Adrenocorticotropic Hormone↗
PubMed1987

Penicillin tolerance in Streptococcus faecium ATCC 9790.

Tolerant strains of Streptococcus faecium had higher levels of muramidase 2 and lower levels of trypsinactivable muramidase 1 than did susceptible strains. Susceptible strains lysed faster than did tolerant strains in buffer and at some antibiotic concentrations. The addition of Triton X-100 produced equal lysis rates for susceptible and tolerant cultures.

Bacteriolysis↗
PubMed1987

Opioid control of luteinizing hormone secretion in patients with hirsutism and hyperandrogenemia.

The present study was designed to evaluate the influence of hyperandrogenemia on the activity of the opioid system regulating LH secretion in menstruating women. Ten subjects presenting with hirsutism and hyperandrogenemia and 9 healthy normally cyclic subjects participated in the study. Naloxone or saline was administered on 2 different days both during the follicular (6-8 days after menstrual bleeding) and during the luteal phase of the menstrual cycle. Naloxone significantly increased plasma LH levels in the luteal, but not during the follicular phase of the cycle in both subject groups. It may be inferred from these observations that opioid-mediated inhibition of LH secretion is not altered in menstruating hyperandrogenic patients, suggesting that the circulating androgens are not an important determinant of the functional neuroendocrine activity of the opioid system.

Adult↗
PubMed1987

Progesterone and progestins modulate beta-endorphin concentrations in the hypothalamus and in the pituitary of castrated female rats.

Hypothalamic and pituitary beta-endorphin (B-EP) concentrations are modified by ovariectomy and estrogen treatments, supporting a direct interaction between this peptidergic system and gonadal steroids. Because the use of progestins is becoming even more diffuse in clinical practice, we evaluated the effect of progesterone and of the synthetic progestins medroxyprogesterone acetate (MPA), norethisterone acetate (NET) and desogestrel on the concentration of B-EP in the medial-basal hypothalamus and the anterior and neurointermediate pituitary lobes in ovariectomized rats (OVX), treated or untreated with estradiol benzoate (EB). B-EP concentrations were significantly increased by desogestrel in the anterior lobe and by progesterone, desogestrel and medroxyprogesterone acetate in the neurointermediate lobe. Progesterone and progestins significantly reduced B-EP increase induced by estradiol benzoate in the anterior lobe. Estradiol benzoate treatment did not modify the effect of progesterone and desogestrel on B-EP in the neuro-intermediate pituitary lobe. Norethisterone acetate and progesterone increased B-EP concentrations in the medial-basal hypothalamus, while the other steroids were inactive. In contrast, in the hypothalamus all progestins attenuated the increase of B-EP induced by estradiol benzoate (p less than 0.01). These data indicate that progesterone and progestins modulate the hypothalamic and pituitary B-EP concentrations in concert with estrogens. The capacity of progestins to modify the hypothalamic contents of B-EP may represent one of the mechanisms of action of these steroids in influencing brain function.

Animals↗
PubMed1986

Opioid control of LH secretion in humans: menstrual cycle, menopause and aging reduce effect of naloxone but not of morphine.

A number of studies have been made on the role played by endogenous opioid peptides in the secretion of LH in humans. However no previous studies have compared the effects of the most potent pharmacological agonist and antagonist, morphine and naloxone, in the same subjects. The present study examined the acute effects of injections of morphine and naloxone on plasma LH levels in 30 healthy subjects (18 women and 12 men). Fertile women were subdivided into follicular (n = 6) and luteal (n = 6) phase groups; the remaining 6 were postmenopausal women. The 12 men were sub-divided in two groups of 6 subjects according to age (24-33 years, and over 60 years). There was a two day interval between injection studies in the same subjects. Morphine significantly decreased plasma LH levels in all groups examined (P less than 0.01). On the other hand, naloxone caused a significant increase in plasma LH levels in fertile women during the luteal phase of the cycle, but not during the follicular phase or in postmenopausal subjects, and in young but not in aged men (P less than 0.01). These results indicate that in humans there is a change in the activity of the opioids regulating LH secretion during the menstrual cycle, after menopause and in aged men and that these may be studied by the use of naloxone. The inability of naloxone under certain conditions to increase LH levels reflects the decreased activity of the endogenous system, while morphine, being active in all the subjects, seems to be less discriminative, at least in physiological conditions.

Adult↗
PubMed1986

Reduced estriol and dehydroepiandrosterone sulphate plasma levels in methadone-addicted pregnant women.

The plasma levels of human chorionic somatomammotropin (hCS), estriol (E3), dehydroepiandrosterone sulphate (DHA-S), cortisol and the circadian changes of the two last adrenal hormones were studied in 25 pregnant methadone-addicted women (MA) and 21 pregnant drug-naive controls (C) at different periods of gestation and in 13 non-pregnant women (7 MA and 6 drug-naive). MA pregnant women showed normal plasma levels of hCS both at the second (6.9 +/- 0.1 vs. 7.2 +/- 0.1 micrograms/ml) and third (9.6 +/- 0.2 vs. 9.3 +/- 0.2) trimester, while plasma concentrations of E3 at term were lower than normal (MA: 4.4 +/- 0.8; C: 8.2 +/- 1.0 ng/ml, P less than 0.05). DHA-S plasma levels of MA pregnant women were half the normal values in three trimesters of gestation, while there were no differences in non-pregnant subjects. Circadian variations of cortisol and DHA-S plasma levels were present in both MA and C. The blunted DHA-S but normal cortisol plasma levels found in MA pregnant women indicate that opiate abuse interferes with adrenal function, mainly of the fetus. Due to the scarce availability of adrenal precursors, these data suggest that E3 measurements should not be considered as a useful index of fetal well-being in the presence of opiate addiction.

Adult↗
PubMed1986

Benefits and risks of different hormonal replacement therapies in post-menopausal women.

A total of 113 women who presented with climacteric symptoms participated in the study. They were randomly allocated to seven groups of 10-27 subjects, who received for 6 mth the following therapies, respectively: conjugated oestrogens (CE) 0.625 mg/day for 21 days + norethisterone (NET) 5 mg/day from day 12 to day 21; CE + cyproterone acetate (CPA) 12.5 mg/day from day 1 to day 10; oestradiol valerate (EV) 2 mg/day for 21 days + NET; EV + CPA; oestriol (E3) 2-4 mg/day; tibolone (ORG OD14) 2.5 mg/day; and placebo, one tablet/day. Hot flushes decreased significantly over the treatment period in all seven groups. However, E3 was less effective at the dose used than CE, EV or ORG OD 14. At the end of the 6 month treatment period histological examination revealed no changes in endometrial morphology in any of the patients treated. Indeed, the addition of a progestogen even induced regression of endometrial hyperplasia in 8 cases. No significant variation in the plasma levels of triglycerides, total cholesterol, high-density lipoprotein (HDL) or low-density lipoprotein (LDL) was observed after the second and sixth months of treatment with E3 or ORG OD 14. After 6 months, treatment with CE/EV + CPA produced a significant increase in HDL, while treatment with CE/EV + NET brought about a reduction in total cholesterol and HDL and an increase in LDL.

Adult↗
PubMed1986

Somatostatin and oxytocin infusion inhibits the rise of plasma beta-endorphin, beta-lipotrophin and cortisol induced by insulin hypoglycaemia.

The present study investigated the possible effect of somatostatin and oxytocin on the basal and stress-induced rise of beta-endorphin (beta-END), beta-lipotrophin (beta-LPH) and cortisol in the human. For this purpose somatostatin (4.1 micrograms/min for 120 min or oxytocin (0.4 micrograms/min for 120 min) was infused into two different groups of seven healthy subjects; 30 min after the start of the infusion, placebo or insulin (0.1 IU/kg body weight, B.W.) was injected on two different days. In a third experimental step, an insulin tolerance test was performed during saline infusion to evaluate stress-related effects on the different hormonal secretions under basal conditions. Plasma levels of beta-END, beta-LPH and cortisol were measured by radioimmunoassay. Extraction and chromatographic procedures preceded the assay for beta-END and beta-LPH. Neither somatostatin nor oxytocin significantly modified basal plasma levels of beta-END, beta-LPH and cortisol. However these treatments blunted the rise of the three hormones seen at 45 and 60 min during insulin-induced hypoglycaemia (P less than 0.01). These results indicate that somatostatin and oxytocin may influence the beta-END, beta-LPH and cortisol increase induced by stress in humans, without affecting their basal secretion.

Adult↗