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Biomedical subjects

C Foresta

Publications and source records attributed to C Foresta.

At least 127 records · Page 7Linked to original sources
PubMed1986

Localization of met-enkephalin on human spermatozoa and evidence for its physiological role.

Pro-opio-melano-cortino-derived peptides have been identified in rat testicular extracts and in human seminal plasma, but their physiological role is still unknown. We report that met-enkephalin is localized on human spermatozoa, by means of an indirect immunofluorescent technique. Furthermore, we demonstrate that a met-enkephalin analog (D-Ala2-Mephe4-Met-(o)-ol-enkephalin, FK 33-824, Sandoz, Basel, Switzerland: DAMME) inhibits in a dose-dependent manner the acrosome reaction induction. The hypothesis of a physiological role of seminal met-enkephalin on human spermatozoa fertilizing ability is briefly discussed.

Acrosome↗
PubMed1985

Testosterone and calcitonin plasma levels in hypogonadal osteoporotic young men.

The aim of this study was to ascertain whether there was an interrelationship between male osteoporosis, calcitonin and androgens. Ten young hypogonadal osteoporotic men were studied: testosterone and calcitonin plasma levels were measured before and after therapy with testosterone enanthate (200 mg im every three weeks for four months). In these patients testosterone and calcitonin plasma levels were significantly lower than controls, before therapy (p less than 0.001 and p less than 0.01 respectively). Testosterone treatment significantly increased (p less than 0.05) serum calcitonin. The conclusion was that androgen deficiency may cause osteoporosis also by decreasing calcitonin secretion.

Adult↗
PubMed1985

Lack of effect of im diazepam administration on hGH and hPRL secretion in normal and acromegalic subjects.

The usefulness of diazepam as a provocative stimulus for hGH secretion has been suggested as a simple, reliable test in clinical hGH assessment of pituitary disorders. We have investigated the effects of diazepam (10 mg im) on plasma hGH and hPRL in 5 normal and 7 acromegalic subjects. No significant variations in hGH and hPRL levels have been observed in any of the studied subjects. These findings indicate that the drug is ineffective on hGH and hPRL release and that it cannot be considered a valid provocative test either in normal or acromegalic subjects.

Acromegaly↗
PubMed1985

Serotonin but not dopamine is involved in the naloxone-induced luteinizing hormone release in man.

Endogenous opioid peptides exert a tonic inhibition on gonadotropin secretion at the hypothalamic level, but the mechanisms by which they act are still unknown. Previous experimental studies suggest that the endogenous opioid peptides change dopaminergic and serotoninergic tones at the hypothalamic level. We have investigated whether the stimulatory effect of naloxone on luteinizing hormone (LH) secretion is due to its influence on these neurotransmitters. Two experimental models were studied, and two sets of effects on LH secretion induced by intravenous naloxone infusion (20 mg over 2 hours) in 14 normal men 20 to 25 years of age were evaluated: the effect of oral sulpiride (150 mg), a potent dopaminergic antagonist, and the effect of oral fenfluramine (60 mg), a drug that stimulates the serotoninergic receptors by releasing serotonin and inhibiting its reuptake. The study demonstrated that naloxone infusion significantly stimulated the LH secretion throughout the period of observation (P less than 0.01 versus saline). The pretreatment with sulpiride did not change the LH response to naloxone. After fenfluramine pretreatment, naloxone failed to induce any rise in LH secretion. Follicle-stimulating hormone did not show any important variation in either test. The data suggest that in man the stimulatory ability of the opiate receptor antagonist naloxone to elicit a rise in LH plasma levels may involve the serotoninergic, but not the dopaminergic, hypothalamic system. This hypothesis, however, does not exclude the involvement of other hypothalamic neurotransmitters.

Adult↗
PubMed1985

Dopamine is not involved in the opioid control of luteinizing hormone secretion in man.

The aim of this study was to examine the role of the central dopaminergic system in the mechanisms by which opioid peptides exert their influence on luteinizing hormone (LH) secretion in man. The effects of sulpiride and naloxone on the changes in LH secretion induced by a metenkephalin analog (D-Ala2-MePhe4-Met-(o)-ol-Enkephalin, FK 33824, Sandoz, Basel, Switzerland) (DAMME) and dopamine infusion in four castrated men (21 to 25 years of age) were studied. In these patients, sulpiride pretreatment counteracted the inhibitory effect of dopamine but did not alter the fall of LH plasma levels that DAMME induced. Moreover, in these subjects naloxone reduced the inhibitory effects induced by DAMME but did not change the inhibitory effect of dopamine on LH secretion. These findings confirm that central dopaminergic and opiatergic systems play a role in the control of LH secretion; the data also exclude any interaction between these systems in regulating LH secretion.

Adult↗
PubMed1985

Gonadal steroids deficiency and prolactin response to a met-enkephalin analog in man.

The aim of this study was to ascertain whether there is a correlation between gonadal steroids and opioid control of prolactin (PRL) secretion. Four castrated men, aged 18 to 24 years were submitted to intravenous injection of 250 ug of a met-enkephalin analog (D-Ala2-Mephe4-Met-(o)-ol-Enkephalin, FK 33824) (DAMME). In normal men DAMME injection was also performed on the 6th day after treatment with clomiphene citrate (CC) (200 mg/day for 5 days), a specific nonsteroidal estrogen receptor blocker. In castrated men and in normal men after CC treatment, there was a lower PRL response to DAMME than in controls (P less than 0.0005). These results suggest that gonadal steroid deficiency seems to cause a change in the opioid system and/or dopaminergic control of prolactin secretion.

Adolescent↗
PubMed1985

Naloxone reduces the fenfluramine-induced prolactin release in man.

In order to ascertain whether there is a relation between opioids and the serotoninergic system in prolactin (PRL) secretion increase, we investigated in seven healthy men (21 to 26 years of age) the effect of naloxone, a specific opioid antagonist, on PRL secretion induced by fenfluramine, a drug that stimulates serotonin release and inhibits its re-uptake. We observed that subjects receiving fenfluramine (60 mg orally) had a significantly (P less than 0.001) higher increase in PRL plasma levels than the controls receiving placebo. In all subjects naloxone infusion at a dose of 15 mg caused a significant reduction (P less than 0.0005) in the PRL response to fenfluramine. Higher doses of naloxone (30 mg) do not further inhibit the PRL secretion induced by fenfluramine. These results suggest that naloxone may interact with opiate receptors on serotonin neurons thereby reducing the synthesis and release of serotonin. It seems that in man, therefore, there is an interplay between opiates and the serotoninergic system in the facilitatory influence on PRL release.

Adult↗
PubMed1985

Effects of a met-enkephalin analogue on motility, O2 consumption, and ATP content of human spermatozoa.

Opioid narcotics are present in seminal plasma, although their physiological effect on spermatozoa is still unknown. This study reports data on metabolic parameters of human spermatozoa in the presence of a met-enkephalin analogue: D-Ala2-Mephe4-Met-(o)-ol-Enkephalin, FK 33824, Sandoz, Basel, Switzerland (DAMME), and its receptor antagonist naloxone hydrochloride, Endo Laboratories, Garden City, New York. Our findings indicate that the metenkephalin analogue reduces sperm motility and cellular O2 consumption without affecting cellular ATP content and viability. The hypothesis that DAMME acts on adenylate-cyclase is briefly discussed.

Adenosine Triphosphate↗
PubMed1984

The influence of gonadal steroids on the dopamine inhibitory effect on gonadotropin release in men.

The aim of this study was to ascertain whether an interrelationship exists between gonadal steroids and the inhibition of gonadotropin secretion by dopamine. The effect of dopamine infusion (4 micrograms/kg/minute intravenously) on gonadotropin plasma levels in four castrated men (18 to 23 years of age) and in four age-matched normal men was studied. Normal subjects were studied before and after treatment with a specific nonsteroidal estrogen receptor antagonist, CC. LH plasma levels in normal subjects receiving CC had a maximum decrease percentage and a net decrease significantly greater (P less than 0.005 and P less than 0.012, respectively) than those before CC treatment. In castrated subjects the maximum decrease percentage was significantly greater (P less than 0.005) than in control subjects, but it did not show any difference from that of normal subjects receiving CC. In none of the group were significant changes in FSH concentration observed. The findings suggest that whenever there is a gonadal steroid deficiency, dopamine infusion causes an increased sensitivity to LH inhibition. This may be due to a lower endogenous dopaminergic influence on LH secretion.

Adolescent↗
PubMed1984

Naloxone fails to increase LH levels in clomiphene treated men.

The gonadotrophin response to the opiate antagonist naloxone administered per infusion has been investigated before and after 5 days of clomiphene treatment in 5 male subjects. Before clomiphene treatment, naloxone caused a significant increase in LH levels, however, after clomiphene, naloxone failed to induce the same effect. An important role for gonadal steroids on the opiatergic inhibitory tone of LH secretion in man is suggested.

Adult↗
PubMed1984

Osteoporosis and decline of gonadal function in the elderly male.

The bone mineral content was evaluated in 30 male subjects aged between 60 and 90 years using the relief of the percent cortical area (PCA) at the level of the second phalanx of the left-hand index finger, by Garn's method. This was to evaluate the rate of bone loss with increasing age. Testosterone, androstenedione, estrone, 17 beta-estradiol plasma levels were determined in all subjects by the RIA method. 60% of our patients showed increased bone resorption (PCA less than 55%); in these subjects testosterone and androstenedione plasma levels were significantly lower than in subjects not affected by osteoporosis. A positive linear correlation is evident between PCA and testosterone, androstenedione and estrone plasma levels. Thus, like in women, decline of gonadic function determines an increased bone resorption in men too.

Aged↗
PubMed1984

Autoantibodies against Leydig cells in patients after spermatic cord torsion.

This study is aimed at searching for the presence of circulating antibodies against frozen sections of human testis, ovary and trophoblast in patients that had spermatic cord torsion. Sixty-eight sera samples were studied. Nine patients (13.2%) were positive for organ specific anti-testis autoantibodies. Six patients were positive for antibodies against Leydig cells: five were positive only with the indirect immunofluorescence technique of complement fixing (ITT/CF), the sixth patient was positive only with the indirect immunofluorescence technique (ITT). The other three patients were positive for antibodies against germ line cells: two patients were positive with both techniques, the third was positive only with indirect immunofluorescence technique. Eight of these patients were negative for antibodies against adrenal cortex while only one case was positive with indirect immunofluorescence technique both on adrenal cortex and Leydig cells. Human lyophilized testis absorbed the reactive antibodies against Leydig cells and germ line cells, while adrenal cortex and lyophilized testosterone were ineffective. This study shows the identification of a specific antibody against Leydig cells and germ line cells in patients after spermatic cord torsion.

Adolescent↗
PubMed1983

Gonadal steroids and opioid control of gonadotropin secretion in man.

The aim of this study was to ascertain whether there was an interrelationship between gonadal steroids and endogenous opioid peptides. The effects of naloxone (20 mg, intravenously) and of a met-enkephalin analog (DAMME) (250 micrograms, intravenously) on gonadotropin secretion in three castrated men (18 to 23 years of age) and in five age-matched normal men were studied. Normal subjects were studied before and after treatment with a specific nonsteroidal estrogen receptor antagonist, clomiphene. Naloxone caused a significant increase in luteinizing hormone (LH) (P less than 0.05); in these subjects, clomiphene treatment significantly increased LH and follicle-stimulating hormone plasma levels but totally suppressed the naloxone-induced rise in LH. In castrated men, naloxone failed to increase plasma LH levels. However, DAMME significantly reduced plasma LH levels in normal, in castrated, and in clomiphene-treated normal subjects. The results demonstrate that in castrated subjects who lack gonadal steroids and in normal subjects with blocked estrogen receptors there is a reduced opioid inhibitory tone on gonadotropin secretion. The effect of DAMME on gonadotropin secretion, however, is not influenced by the gonadal steroid environment.

Adolescent↗
PubMed1983

Sex hormone-binding globulin and saliva testosterone levels in men with androgenetic alopecia.

Sex hormone binding globulin (SHBG), plasma testosterone and saliva testosterone were measured in sixty-four men with androgenetic alopecia and in forty males within the same age range without alopecia. There was a significant reduction in SHBG levels in bald men, compared with controls. Plasma testosterone levels were not raised in bald men, but their salivary testosterone levels were significantly higher than in controls.

Adolescent↗