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Biomedical subjects

A Polleri

Publications and source records attributed to A Polleri.

84 records · Page 5Linked to original sources
PubMedDate not supplied

Circadian rhythmicity of prolactin secretion in elderly subjects: changes during bromocriptine treatment.

Prolactin has been taken as an index of neuroendocrine function in aging, where dopaminergic neurotransmission in considered to be impared. The mean concentration of the hormone in the 24 h is higher in the aged men than in the adult controls. A sleep entrained periodicity is present in both aged subjects and controls, but a harmonic analysis of rhythmicity shows that secretory episodes have in aged men a slower periodicity than in adults. In aged men bromocriptine decreases the mean PRL values in the 24 h and the periodicity analysis shows the occurrence of harmonics with shorter period.

Adult↗
PubMedDate not supplied

[Correlations between E.E.G. spectral and plasma prolactin levels in elderly subjects (author's transl)].

Measurement of plasma prolactin levels in elderly subjects demonstrated the presence of a hyperprolactinemia with loss of normal circadian rhythm, regressing after bromocriptine treatment. The administration of bromocriptine to elderly subjects in a normal state of health provokes marked changes in the E.E.G. spectrum (slowing of delta activity, increase in alpha and decrease in beta rhythms). These findings show that there is an alteration in central dopaminergic systems during aging.

Aged↗
PubMedDate not supplied

Prolactin secretion in epileptic subjects treated with phenobarbital: sex differences and circadian periodicity.

Circulating basal prolactin (PRL) levels were evaluated in 126 subjects of both sexes with partial or generalized epilepsy, who were treated with phenobarbital (PB) alone or in combination with either phenytoin or benzodiazepines. A significant increase in PRL levels was observed in male, but not in female, patients compared with a sex- and age-matched healthy volunteer group. Circadian PRL secretion, studied in six male epileptic patients on PB monotherapy and in nine normal subjects, showed comparable 24-h PRL mean values and a preserved PRL surge during the night in both groups; however, a statistically significant additional peak was found in male epileptic subjects during the late afternoon. The cosinor analysis of the data, used to evaluate PRL rhythmicity, showed a disruption of the 24-h periodicity in epileptic subjects, while the 12-h periodicity was maintained. These results indicate that central and/or peripheral mechanisms involved in PRL secretion control are more sensitive to PB alone or in combination with other antiepileptic drugs in male than in female subjects. However, the changes of PRL secretion we found were small and unrelated to the different clinical conditions.

Adolescent↗
PubMedDate not supplied

Cholinergic modulation of growth hormone-releasing hormone effects on growth hormone secretion in dementia.

An impairment of cholinergic and somatostatinergic neurotransmission have been reported in dementia. Both acetylcholine and somatostatin are involved in the regulation of growth hormone (GH) secretion. The effects of GH-releasing hormone (GHRH) 1-44 on GH release have been studied before and after the pretreatment with pyridostigmine or pirenzepine in subjects with senile dementia of the Alzheimer type, multi-infarct dementia and mixed dementia. The data have been compared with those obtained in an age-matched healthy control group. The GH response to GHRH is similar in the patients and in the controls, though the peak occurrence is significantly delayed in dementia. The cholinesterase inhibitor pyridostigmine enhances significantly the GH response to GHRH in both groups. The responses obtained in demented subjects are significantly larger than those found in the controls. Pirenzepine, a muscarinic receptor blocker, inhibits the GHRH effect on GH secretion in both groups. The findings may be interpreted in terms of an underlying impairment of the hypothalamic cholinergic neurotransmission, with an acetylcholine receptor supersensitivity that becomes apparent when the cholinergic tonus is enhanced by the inhibition of cholinesterase by pyridostigmine. No significant differences, due to the type of dementia, have been observed.

Acetylcholine↗
PubMedDate not supplied

The 24-h pattern of human prolactin in serum.

Radioimmunoassay determinations of serum prolactin every 2 hrs in twelve healthy subjects (six women and six men), aged between 22 and 34, reveal that several episodes of hormone secretion occur over a 24-h period. The two episodes displaying significant oscillations have 24-h and 8-h periods, with maxima occurring respectively at 04(30) and at 07(00), 15(00) and 23(00). Accordingly, the highest prolactin levels in serum occur during the night, but oscillations are present throughout the day. The observation schedule adopted leads us to conclude that the main secretory rhythm is synchronized with sleep. The 8-h periods seem to be rather dependent on the course of time.

Adult↗
PubMedDate not supplied

[The neuroendocrine aspects of chronic alcoholism: the effect of alcohol intake and its withdrawal].

Neuroendocrine dysfunctions, in part similar to those found in depression, are present in chronic alcoholism. The aim of this investigation was to evaluate the effects of chronic alcohol intake on cortisol secretion in basal conditions, after dexamethasone (DXT) suppression or corticotropin (ACTH) stimulation in 10 alcoholic men, during active drinking and after two weeks of alcohol withdrawal. The 24-hour, day- and night-time urinary cortisol and melatonin levels, and the effects of thyrotropin releasing hormone (TRH) on thyrotropin (TSH) and prolactin (PRL) secretions were studied in the same subjects. The data were correlated to the scores obtained by the Hamilton Rating Scale for depression and compared to those found in healthy subjects. Increased cortisol levels and the lack of DXT suppression of cortisol secretion are considered to be alcohol-dependent inasmuch as they disappear in most patients after alcohol withdrawal. The cortisol response to ACTH 1-24 infusion measured before and after alcohol withdrawal was similar in the patients we studied; moreover no significant difference was found between patients and controls. The increment of urine free cortisol levels in active alcoholics was not statistically significant. Urine cortisol levels became similar to those of the control subjects after alcohol withdrawal. The increased diurnal values of urine melatonin and the inversion of the physiological ratio between nocturnal and diurnal levels observed during alcohol intake became normal upon alcohol withdrawal. The TSH and PRL responses after the administration of 50 or 200 micrograms TRH were higher in alcoholics than in controls, while a blunted response is known to occur in depression.

Adult↗
PubMedDate not supplied

TSH circadian secretions in aged men and effect of phosphatidylserine treatment.

In 20 euthyroid aged men (from 65 to 85 years of age) no significant circadian periodicity of thyrotropin (TSH) secretion has been shown by the population mean cosinor method. At the end of a period of 30 days of hospitalization the cosinor evaluation of TSH secretion showed a restored highly significant (p less than 0.001) circadian rhythmicity in phosphatidylserine (PS) (400 mg/daily) treated group (10 aged subjects). By contrast, hospitalization seems to further deteriorate the periodicity of the hormone secretion in 10 placebo-treated subjects.

Aged↗
PubMedDate not supplied

Melatonin and cortisol circadian secretion during ethanol withdrawal in chronic alcoholics.

Changes in central neurotransmission and in hypothalamo-pituitary function occur in both ethanol (ETOH) intake and withdrawal. Melatonin (MLT) secretion is regulated by the noradrenergic system, which is activated upon ETOH withdrawal. Experimental evidence exist that pineal gland may have a role in ETOH intake and preference in rats. Twenty-four hour urinary excretion of MLT was found to be increased during ETOH intake in chronic alcoholics. In this study we have determined 24h plasma levels of MLT and cortisol in 8 chronic alcoholic males hospitalized for a detoxication program and in 8 healthy controls. The study was performed just after admission, on the first day of ETOH withdrawal and after 14 days of controlled abstinence. Circadian periodicity has been evaluated by the cosinor method. The initial determinations corresponded to the acute withdrawal phase. Twenty-four hour plasma MLT mean levels on acute withdrawal were higher than after 14 days abstinence and than those found in controls. Large interindividual differences prevented the detection of statistical significance. The cosinor analysis disclosed the loss of circadian periodicity in the acute withdrawal. Significant 24h periodicity was restored after 14 days abstinence. Cortisol levels were significantly higher than those found on day 14 and in healthy controls. Twenty-four hour periodicity was maintained in both alcoholics series. A delay in cortisol acrophase occurred in acute withdrawal. The effects of Corticotropin Releasing Hormone infusion on cortisol secretion were significantly enhanced in the acute withdrawal phase in comparison with those occurring when patients were retested and with healthy controls.

Adult↗
PubMedDate not supplied

Effects of valproate, phenobarbital, and carbamazepine on sex steroid setup in women with epilepsy.

Serum levels of sex-hormones, sex-hormone binding globulin, gonadotropin, and prolactin were evaluated during the follicular and the luteal phases in 65 women with epilepsy and in 20 healthy controls. Twenty-one patients were treated with sodium valproate (VPA), 21 with phenobarbital (PB), and 23 with carbamazepine (CBZ). VPA does not stimulate liver microsome enzymes, whereas PB and CBZ do. Patients on VPA therapy showed higher body weight and body mass index, but no significant differences in hirsutism score, or in ovary volume or polycystic ovary prevalence (at ultrasound examination). Estradiol levels were lower in all patient groups than in healthy controls in the follicular but not in the luteal phases. VPA affected luteal progesterone surge in 63.6% of cases. This effect was significantly lower in the CBZ and PB groups. Furthermore, increases in testosterone and delta 4-androstenedione levels and in free androgen index, along with a higher luteinizing hormone-follicle-stimulating hormone ratio in the luteal phase, were observed in women treated with VPA. Although sex-hormone binding globulin levels were higher in CBZ and PB than in VPA-treated patients, the differences were not significant because of the wide dispersion of the carrier protein levels. Inducer antiepileptic drugs decreased dehydroepiandrosterone sulfate levels, which remained unchanged during VPA treatment. No significant differences occurred in basal gonadotropin and prolactin levels.

Adolescent↗