Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0030567 (Parkinson's disease)
 63,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Somatostatin (SRIF) actions in the brain and pituitary are mediated by specific receptors. Using radioiodinated ligands it has been possible to characterize the kinetics of specific binding sites in the brain and pituitary, and to determine their cellular localization by autoradiography. At the pituitary level, the inhibition of growth hormone, prolactin and thyrotropin secretions induced by SRIF is mediated through a single binding site which is coupled to the inhibition of adenylate cyclase. In the brain, SRIF receptors are localized on neurons and glial cells and are also coupled to adenylate cyclase inhibition. Two sites are differentiated in the brain with an analogue of somatostatin, SMS 201995. In humans, SRIF-binding sites have been related to a number of pathologies. At the pituitary level, it has been shown that the number of binding sites was negatively correlated to growth hormone levels in acromegaly. Furthermore, SRIF-binding sites were undetectable in a patient which did not respond to SMS 201995 therapy. In the brain, meningiomas and gliomas are rich in SRIF binding sites. This suggests a possible role for SRIF on glia. In neurodegenerative diseases, cortical SRIF concentrations are decreased in Alzheimer's and Parkinson's disease associated with dementia while SRIF-binding sites are only affected in Alzheimer's disease. In conclusion, the physiological role of SRIF in the brain and pituitary can be evaluated by studying the receptors of the peptide. Such studies allow to question the implication of SRIF in endocrine and neuropathologies.
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PMID:Somatostatin receptors in brain and pituitary. 256 73

It is currently believed that Parkinson disease (PD) is due to a degenerative process that independently damages multiple areas of the central and peripheral nervous system. Loss of nigrostriatal dopamine is now widely recognized as being directly related to the motor symptoms in Parkinson's disease. Parkinsonian patients also exhibit symptoms and signs suggestive of hypothalamic dysfunction (e.g. dysautonomia, impaired heat tolerance). The latter clinical features are supported by pathological, biochemical and endocrinological findings. Lewy body formation has been demonstrated in every nucleus of the hypothalamus, specifically the tuberomamillary and posterior hypothalamic. Preferential involvement of the hypothalamus was also noted in patients after post-encephalitic parkinsonism. Loss of dopamine (30-40%) in the hypothalamus of affected patients has been shown in recent studies, and is compatible with the reported abnormalities of growth hormone release in response to L-dopa administration, elevated plasma levels of MSH, and reduced CSF levels of somatostatin and beta-endorphins in these patients. Deranged immunological mechanisms have been found in PD patients including the presence of autoantibodies against sympathetic ganglia neurons, adrenal medulla and caudate nucleus. On the evidence of on pathological studies demonstrating the early vulnerability of the hypothalamus in aging and PD, and the known role of the hypothalamus in immune modulation, we expect that it will be shown that primary damage of the hypothalamus leads to subsequent secondary degeneration of structures receiving direct projections from the hypothalamus. Within this framework, the dopaminergic systems may be damaged, since striatal dopamine synthesis and receptor sensitivity have been shown to be regulated by ACTH and alpha-MSH through direct arcuate nucleus-striatal projections.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The hypothalamus in Parkinson disease. 288 37

The neuroendocrine function is regulated by several neurotransmitters (acetylcholine, dopamine, somatostatin and noradrenaline) known to be reduced in brains of patients with Alzheimer's disease (AD). Moreover, the hypothalamus also has pathological changes. In spite of these findings suggesting neuroendocrine dysfunctions, this function has seldom been investigated in AD patients so far. We have compared patients with clinically 'probable' AD of mild-to-moderate severity with nondemented age- and sex-matched controls. Plasma levels of prolactin (PRL), growth hormone (GH) and thyroid-stimulating hormone (TSH) were measured by commercially available radioimmunoassays (RIA) before and after stimulation with metoclopramide, l-dopa or thyrotropin-releasing hormone. Basal plasma levels of beta-endorphin and beta-lipotropin were measured by RIA after high-performances liquid chromatography. Basal and stimulated plasma levels of PRL, GH, TSH and beta-lipotropin were similar in the two groups. Basal lamina levels of beta-endorphin were significantly higher in the patient group. Of doubtful clinical importance, this might be attributed to decreased tuberoinfundibular dopaminergic activity and has also been seen in patients with Parkinson's disease.
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PMID:Neuroendocrinological function in Alzheimer's disease. 297 29

Thirteen drug-free and not severely affected patients with idiopathic Parkinson's disease underwent an insulin-hypoglycaemia test, a TRH test and a levodopa test. The responses of growth hormone, prolactin, cortisol and thyrotropin were measured, and retested under stable therapy with levodopa and benserazide. Mean basal and stimulated hormonal concentrations were in the normal range before and during therapy. Minor abnormalities were observed in individual cases, but did not indicate a hypothalamic dopamine deficit.
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PMID:Effect of hypoglycaemia, TRH and levodopa on plasma growth hormone, prolactin, thyrotropin and cortisol in Parkinson's disease before and during therapy. 308 17

A deficit of nigrostriatal, mesocortical and mesolimbic dopamine systems in Parkinson's disease is well known. We know less about the involvement of tuberoinfundibular dopamine (TID) systems. In untreated (naive or wash-out) men with Parkinson's disease, we studied TID function through basal and stimulated plasma levels of growth hormone, prolactin and thyrotropin. Only minor abnormalities in prolactin responses to thyrotropin-releasing hormone were found, probably reflecting denervation hypersensitivity. TID function is preserved in men with Parkinson's disease.
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PMID:Tuberoinfundibular dopaminergic function in Parkinson's disease. 313 13

Bromocriptine, a specific dopamine receptor agonist, has been used for the treatment of various hyperprolactinemic conditions and as adjunctive therapy for acromegaly (with or without concomitant hyperprolactinemia) and Parkinson's disease. Bromocriptine is extremely effective in suppressing prolactin secretion regardless of the cause, in restoring gonadal function and fertility, and in decreasing the size of prolactin-secreting pituitary tumors. Most patients with acromegaly have clinical improvement with this drug. When bromocriptine is added to a regimen of levodopa or carbidopa, patients with Parkinson's disease frequently have additional clinical improvement and, in most patients, the levodopa or carbidopa dose can be reduced. Withdrawal of bromocriptine therapy is associated in most patients with reversal of its beneficial effects--return of hyperprolactinemia, return of excess growth hormone secretion, and exacerbation of Parkinson's disease.
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PMID:Drugs five years later. Bromocriptine. 622 5

Plasma prolactin (PRL) and growth hormone (GH) levels were measured in 8 patients with Parkinson's disease (PD) and in 6 patients with Huntington's chorea (HC) during the night. The sleep was evaluated with all-night poligraphic recordings. Plasma PRL levels were significantly lower in parkinsonian patients than in age-matched controls. Plasma GH values did not differ between the two groups. In HC patients no statistically significant differences were found in the PRL and GH secretory patterns when compared to the age-matched control subjects. These data indicate that changes of nocturnal PRL and GH profile in PD and HC patients in respect to age-matched healthy subjects, may be present, but a straight forward differentiation among groups is not possible because of the wide individual variations.
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PMID:Spontaneous nocturnal plasma prolactin and growth hormone secretion in patients with Parkinson's disease and Huntington's chorea. 644 54

The thyrotrophin (TSH) and prolactin (Prl)-releasing effects of TSH-releasing hormone (TRH) were investigated in 20 subjects with Parkinson's disease (PD), unmedicated, on chronic treatment with a combination levodopa-benserazide (Madopar) or levodopa-carbidopa (Sinemet) or withdrawn from therapy. Administration of TRH (200 micrograms iv) induced in unmedicated patients TSH and Prl responses significantly lower than those of sex-and age-matched controls. In patients on Madopar therapy the TSH and Prl responses to TRH were greater than in unmedicated patients and comparable to those of controls, while in patients on Sinemet therapy the pituitary responses were undistinguishable from those of unmedicated subjects. Withdrawal of Madopar therapy resulted in a marked diminution of the TSH response but did not affect the Prl response to TRH. Withdrawal of Sinemet therapy did not alter the TSH and Prl responses to TRH. Concomitant evaluation of growth hormone (GH) levels, in none of the subjects evidenced non-specific changes in plasma GH following TRH. Since TSH and Prl responses to TRH are inhibited by an enhancement of the dopaminergic tone, it would appear that the latter is preserved in the tuberoinfundibular system of unmedicated subjects and subjects on chronic Sinemet therapy, but is defective in subjects on chronic Madopar therapy.
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PMID:Thyrotrophin and prolactin responses to thyrotrophin-releasing hormone in patients with Parkinson's disease. 680 85

Circadian rhythms of prolactin have been evaluated in thirteen untreated parkinsonian patients before and after 15 days of treatment with L-Dopa + carbidopa. The 24th secretory pattern was not significatively different from that observed in controls. The L-Dopa + carbidopa therapy does not change the basal circadian prolactin (PRL) rhythm. These results suggest that the tubero-infundibular dopaminergic system (TIDA) and the PRL secretion are conserved in untreated parkinsonian patients (PP). During chronic L-Dopa + carbidopa therapy, the basal PRL levels, evaluated in 21 PP, showed a correlation with the severity of clinical features. The effects of single doses of apomorphine, bromocriptine, lisuride and haloperidol, were studied on serum levels of PRL in 21 PP divided in two groups of "responders" and "non-responders". Haloperidol induced an enhancement of serum PRL; the dopaminergic drugs, apomorphine, bromocriptine and lisuride inhibited basal PRL secretion. It seems that the TIDA system, in Parkinson disease is not significatively altered, even though presenting a remarkable slower response in "non-responders" to L-Dopa therapy. We also evaluated the effect of L-Dopa, L-Dopa + carbidopa, bromocriptine, lisuride, nomifensine and deprenyl on growth hormone secretion in six PP. The endocrine effects of dopaminergic drugs show a mild rise in comparison with controls suggesting an important alteration in the dopamine (DA) control of growth hormone (GH).
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PMID:Prolactin response as an index of dopaminergic receptor function in Parkinson's disease. Correlation with clinical findings and therapeutic response. 726 25

Madopar, a combination of levodopa with benserazide, induced an inconsistent rise in plasma growth hormone in unmedicated patients with Parkinson's disease and in controls, and a greater growth hormone rise in Parkinsonian subjects on chronic Madopar therapy. In subjects on chronic therapy with levodopa and carbidopa (Sinemet), the growth hormone releasing effect of Madopar was blunted. Madopar increased plasma prolactin (PRL) in controls, unmedicated patients and patients on Madopar therapy while in patients on Sinemet therapy the PRL-releasing effect of Madopar was strikingly reduced. Since these data were interpreted as due to a defective dopamine tone in the hypothalamus of Parkinsonian subjects on Madopar but not Sinemet therapy, a direct dopamine receptor agonist, lisuride was administered. Lisuride, however, elicited a blunted growth hormone response both in patients on Madopar and Sinemet therapy, without revealing a state of supersensitivity of dopamine receptors for growth hormone control in Parkinsonian subjects on Madopar therapy. No difference was present in the PRL-lowering effect of lisuride in the different experimental groups. These findings suggest that: (1) hypothalamic dopamine function is impaired in Parkinsonian subjects on Madopar therapy, preserved in unmedicated patients and enhanced in patients on Sinemet therapy; (2) the endocrine effects observed in Parkinsonian subjects on chronic Madopar therapy may be due to some penetration of benserazide across the blood brain barrier in the region of the hypothalamus; (3) since Madopar and Sinemet are in essence equally effective antiparkinsonian remedies, penetration of benserazide does not occur across the blood brain barrier surrounding the nigrostriatal system.
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PMID:Growth hormone and prolactin stimulation by Madopar in Parkinson's disease. 733 6


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