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Biomedical subjects

E Palazidou

Publications and source records attributed to E Palazidou.

15 recordsLinked to original sources
PubMed1995

Evidence for 5-hydroxytryptamine1A receptor involvement in the control of prolactin secretion in man.

The effects of pindolol pretreatment (2 days) on prolactin and cortisol responses to a single dose of (+)-fenfluramine (30 mg po) were examined in nine healthy male volunteers. Pindolol pretreatment attenuated the (+)-fenfluramine-induced increase in prolactin concentrations but failed to affect the (+)-fenfluramine-induced cortisol increase. These data provide evidence in support of 5-HT1A receptor involvement in the regulation of prolactin secretion but question its importance in the regulation of cortisol secretion in man.

Adult↗
PubMed1994

Involvement of the 5-HT2 receptor in the 5-HT receptor-mediated stimulation of prolactin release.

The present study examined the involvement of 5-HT1C and 5-HT2 receptors in the regulation of prolactin release in the rat. Both the mixed 5-HT2/5-HT1C receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), and the preferential 5-HT1C agonist, 2-chloro-6-(1-piperazinyl)pyrazine monohydrochloride (MK-212), elicited a significant increase in plasma prolactin concentration with DOI about 20 times more potent than MK-212. Treatment with DOI, but not with MK-212, induced head twitching in the rat, and this behavior was inhibited by both the mixed 5-HT2/5-HT1C receptor antagonist, ritanserin, and the selective 5-HT2 receptor antagonist, amperozide. DOI-induced prolactin release was also antagonized by ritanserin and amperozide, whereas only ritanserin affected MK-212-induced prolactin release. Furthermore, amperozide did not attenuate d-fenfluramine-elicited prolactin release, which is known to be antagonized by ritanserin. These data suggest that the pharmacological stimulation of prolactin release by DOI is mediated via the 5-HT2 receptor and that the 5-HT1C receptor may be of importance for the physiological regulation of prolactin release.

Amphetamines↗
PubMed1993

Seasonal affective disorder: response to light as measured by electroencephalogram, melatonin suppression, and cerebral blood flow.

This study was designed to test the hypothesis that patients with SAD have significantly different physiological responses to light than healthy age- and sex-matched controls. We studied retinal contrast sensitivity, visual evoked EEG responses, and melatonin suppression by, and cerebral blood flow response to, full-spectrum artificial daylight. There was no significant difference between 10 patients and 11 controls in retinal contrast sensitivity, or amplitude or latency of N2, P2, P100 or P300 on EEG. We compared melatonin suppression in 12 SAD patients and 12 controls. During exposure to 500 lux and 1500 lux artificial daylight both the SAD patients and controls had a significant melatonin percentage suppression; however, the percentage suppression did not differ significantly between the SAD patients and the controls. In addition, we carried out a small pilot study into the effect of light on cerebral blood flow in four SAD patients and four controls. Before exposure to 1500 lux artificial daylight there was no significant difference between patients and controls in global, regional or cerebral hemispheric blood flow. After light exposure the SAD patients and controls had a significantly different percentage change in cerebral blood flow. We suggest that patients with SAD do not have significantly physiological responses to light than controls, except perhaps in cerebral blood flow. Furthermore, mechanisms other than supersensitivity of melatonin suppression must explain both the pathophysiology of the disorder and its response to treatment with light.

Bipolar Disorder↗
PubMed1993

Melatonin rhythms in seasonal affective disorder.

We examined 24-hour melatonin rhythms from 20 patients with seasonal affective disorder (SAD) and 20 healthy volunteers. Patients and controls were individually matched for age, sex, and month of study. Plasma samples were taken at hourly intervals, and were assayed for melatonin by radio-immunoassay. The 24-hourly melatonin estimations for each individual were fitted to a cosine curve, and the significance of the curve fits was calculated. Two analyses were performed. In analysis 1 the following were calculated: (a) cosine fit, (b) significance of fits, (c) mean amplitude and acrophase (peak) and (d) mean melatonin levels. The curve fits were highly significant for all but three subjects (two patients, one control), but there were no significant differences in any measure between the two groups. In analysis 2 the comparisons were repeated and restricted to the 18 patients and 19 controls in whom there was a significantly significant melatonin rhythm. Again there were no significant differences between groups. These results suggest that the circadian rhythm of melatonin is not abnormal in SAD, and that the therapeutic effect of light in SAD is not mediated by phase shifts in melatonin secretion.

Adult↗
PubMed1992

Noradrenaline uptake inhibition increases melatonin secretion, a measure of noradrenergic neurotransmission, in depressed patients.

Eight patients with endogenous depression who had received no antidepressant treatment for the previous year were treated with the noradrenaline (NA) uptake inhibitor, desipramine (DMI). Pre-treatment plasma melatonin concentrations were normal. After one day of DMI treatment plasma melatonin concentrations were increased but the response was impaired compared to normal subjects. The acute effect of DMI on plasma melatonin persisted after six weeks of treatment. These findings question the hypothesis that beta adrenoceptors are supersensitive in depression and that antidepressant drugs act by down-regulating these receptors.

Adult↗
PubMed1992

The acute and chronic effects of (+) and (-) oxaprotiline upon melatonin secretion in normal subjects.

Ten healthy male subjects were treated for three weeks with (+)oxaprotiline, a selective inhibitor of noradrenaline (NA) uptake and with (-)oxaprotiline which does not inhibit NA uptake. Plasma melatonin concentrations were measured throughout the night at 0, 1, 7 and 21 days and were higher during treatment with (+)oxaprotiline than with (-)oxaprotiline for the entire three weeks of treatment. Since NA stimulates the production and secretion of melatonin, these results are consistent with a sustained increase in noradrenergic activity within the pineal, during 21 days of treatment with an effective NA uptake inhibitor.

Administration, Oral↗
PubMed1991

Endocrine function, psychiatric and clinical consequences in patients with macroprolactinomas after long-term treatment with the new non-ergot dopamine agonist CV205-502.

Although bromocriptine is the mainstay of treatment of macroprolactinomas, its therapeutic usefulness may be limited by poor tolerance, lack of consistent reduction in serum prolactin levels and tumour size, and the necessity for multiple dosing. Consequently new dopamine agonists have been developed, including the long acting non-ergot agonist CV205-502 which has been shown to date to be consistently effective in reducing serum PRL levels and causing tumour shrinkage. Twelve patients were treated for periods of up to 24 months with CV205-502 in doses ranging from 0.075 mg to 1.65 mg once daily. Clinical and psychiatric assessments, biochemical parameters, tumour size determination, and anterior pituitary function tests were performed regularly. Tumour shrinkage was noted in all patients, and varied from 11 per cent reduction to complete disappearance of tumour. Prolactin levels became normal in seven patients and were reduced by more than 90 per cent in the remaining five. Normal menstruation resumed in six of the eight women, one of whom conceived after one year of therapy; libido returned in all patients. Psychiatric complications occurred in three patients necessitating withdrawal of therapy in one. Significant weight loss was noted in 11 of 12 patients. Triglyceride concentrations fell from 1.5 +/- 0.1 to 1.0 +/- 0.1 mmol/l at 12 months (p = 0.006), and cholesterol fell from 6.3 +/- 0.4 to 5.3 +/- 0.3 mmol/l (p = 0.04). The mean TSH response 20 min following TRH injection fell from 14.3 +/- 2.9 to 8.7 +/- 1.3 mU/l at 2 months (p = 0.027). There was a significant increase in the peak growth hormone response to the insulin stress test from basal median (25th-75th centiles) values of 15 (4.4-25.5) mU/l to 24.5 (9-37) mU/l at 2 months (p less than 0.01) and 31 (19.3-63.5) at 12 months (p less than 0.005). CV205-502 is highly effective in the medical management of patients with macroprolactinomas, reducing prolactin levels and tumour size and restoring normal anterior pituitary function. It is, however, associated with the important side effects of weight loss and psychiatric complications which should be drawn to the attention of clinicians.

Adult↗
PubMed1990

In vivo characterisation of 3-iodo-6-methoxybenzamide 123I in humans.

3-Iodo-6-methoxybenzamide (123I-IBZM), a new Dopamine D2 receptor ligand, was used in conjunction with SME 810 brain tomography to study six subjects (one normal volunteer, four schizophrenics and one DAT patient). Initial Dynamic SPET was followed by multislice SPET. High-resolution images of the D2 receptor distribution in the basal ganglia were obtained. The specific binding in D2 receptors of the basal ganglia is highest from 2-4 h p.i. Patients on anti-psychotic drugs showed significantly lower specific binding. Dopamine D2 brain receptor availability in man may now be studied with SPET. Continuous data acquisition with single slice tomography is particularly important in the study of this type of radiotracers.

Adult↗
PubMed1990

Neuroradiological and neuropsychological assessment in anorexia nervosa.

Seventeen patients with anorexia nervosa were examined by computed tomography (CT) and psychometry and compared with ten normal control subjects. The patients were found to have enlarged external cerebrospinal fluid spaces compared to controls. No differences were found in ventricular size and X-ray absorption density measurements between patients and controls. The patients performed abnormally on the symbol digit test, the scores of which displayed a significant negative correlation with the CT scan changes.

Adolescent↗
PubMed1989

An alpha 2 adrenoceptor antagonist, Org 3770, enhances nocturnal melatonin secretion in man.

Nocturnal plasma melatonin concentration was significantly increased in ten normal volunteers following the administration of an alpha 2 adrenoceptor antagonist, Org 3770 (30 mg). This result supports the existence of an alpha 2 adrenergic influence on melatonin secretion in man and provides a possible clinical neuroendocrine marker of the action of an alpha 2 antagonist.

Adrenergic alpha-Antagonists↗
PubMed1988

Pharmacologic exploitation of neurotransmitter receptors for the design of novel antidepressant drugs.

The term 'psychopharmacology' was coined as early as 1920, by David Macht, but it was not until three decades later that the discipline started to develop in a substantial way. The fortuitous discovery of the first antipsychotics and antidepressants, in the 1950s, presented new horizons and gave impetus to the study of drug treatments in psychiatry. In the 1980s, advances in the basic neurosciences, and especially in the characterisation of neurotransmitter receptors, are presenting new opportunities for understanding the biology of mental illness and for designing new drug treatments. This article reviews the evidence linking the action of antidepressant drugs to the regulation of neurotransmitter receptors. We then show how this information has led to a pharmacologic model (melatonin secretion by the human pineal) for the study of antidepressants in depressed patients. Finally, we outline how pharmacologic exploitation of neurotransmitter receptors might lead to new approaches for the design of novel antidepressant drugs.

Animals↗