<scp>L</scp>-Dopa Stimulated Growth Hormone Release in the Blind

Bellastella, Antonio; Colucci, C F; D'Alessandro, B; Cicero, M. Lo

doi:10.1210/jcem-44-1-194

Cited by 19 publications

(4 citation statements)

References 12 publications

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“…There is also some evidence that melatonin may modulate G H secretion in humans; while oral administration of melatonin causes a small increase in basal G H release, it greatly reduces the G H responses to insulin-induced hypoglycaemia and L-tryptophan (Smythe & Lazarus, 1974a, 1974bKoulu & Lammintausta, 1979). A physiological role for the pineal gland in the regulation of GH secretion is supported by the fact that blind human subjects show reduced GH responses to L-dopa administration (Bellastella et al, 1977) and have absent nocturnal peaks of GH release (Krieger & Glick, 1971). However this latter finding should be interpreted with caution, since blind subjects have a greatly reduced frequency of stage I11 and IV sleep.…”

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confidence: 99%

Effect of Oral Administration of Melatonin on Gh Responses to GRF 1–44 in Normal Subjects

Valcavi

Diéguez

Azzarito

et al. 1987

Clinical Endocrinology

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In order to investigate the role of melatonin on the neuroregulation of GH secretion, eight healthy male volunteers each underwent four separate tests in random order separated by at least 1 week. Following oral administration of melatonin (500 mg at -60 min and at -30 min) plasma GH levels were higher than after placebo at 45 min (mean +/- SEM 2.9 +/- 0.8 vs 0.9 +/- 0.4 ng/ml, P less than 0.01) and 60 min (mean +/- SEM 2.9 +/- 0.4 vs 0.8 +/- 0.1 ng/ml, P less than 0.05). Likewise, after prior administration of melatonin, GH responses to GRF 1-44 (1 micrograms/kg i.v. at 0 min) were greater than placebo plus GRF at 15 min (mean +/- SEM 22.4 +/- 6.1 ng/ml vs 11.3 +/- 2.3 ng/ml, P less than 0.05), 45 min (mean +/- SEM 26.2 +/- 5.3 ng/ml vs 13.3 +/- 2.5 ng/ml, P less than 0.01) and 60 min (mean +/- SEM, 24.7 +/- 7.4 ng/ml vs 11.1 +/- 2.5 ng/ml, P less than 0.05). In contrast we did not observe any effect of either 10(-9)M, 10(-7)M melatonin on in-vitro basal GH release and GH responses to 10(-8)M GRF by rat anterior pituitary cells in monolayer culture. These data suggest that melatonin plays a facilitatory role in the neuroregulation of GH secretion, probably by acting at the hypothalamic level.

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confidence: 99%

Effect of Oral Administration of Melatonin on Gh Responses to GRF 1–44 in Normal Subjects

Valcavi

Diéguez

Azzarito

et al. 1987

Clinical Endocrinology

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“…Several endocrine alterations have been found in blind subjects (Krieger & Glick, 1971;Smith et al, 1981;Lewy & Newsome, 1983;Sack et al, 1992;Bellastella et al, 1977;1990;1994). Several endocrine alterations have been found in blind subjects (Krieger & Glick, 1971;Smith et al, 1981;Lewy & Newsome, 1983;Sack et al, 1992;Bellastella et al, 1977;1990;1994).…”

Section: Discussionmentioning

confidence: 99%

Melatonin and the pituitary‐thyroid axis status in blind adults: a possible resetting after puberty

Bellastella

Criscuolo

et al. 1995

Clinical Endocrinology

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A possible resetting of pituitary-thyroid axis regulation can occur in blindness after puberty; variations of melatonin secretion could play a role in this. The inhibitory effect of melatonin on thyroid gland function found in animals does not seem to occur in humans. Elevated melatonin levels, both in patients with total blindness and in those with light perception only, suggest that more complex mechanisms other than light signalling are involved in the changes of melatonin secretion in blindness.

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“…Some lower peaks may be observed during inter-meal intervals and during afternoon naps. Even if sleep plays a pivotal role in regulating the daily variations in GH secretion, a complementary synchronizing role of the light/dark cycle on this secretion may not be excluded, considering that in blind subjects the nocturnal peak is lacking, the response of GH to L-Dopa stimulated test is impaired, and prepubertal subjects with total blindness show impairment of body growth [7,[61][62][63]. Moreover, disorders of GH secretion with impaired or absent nocturnal peak, have been described in obese patients, in patients with hypothalamic-pituitary diseases, and in prepubertal and adult patients with GH deficiency [5,8].…”

Section: Growth Hormonementioning

confidence: 99%

Chrono-Endocrinology in Clinical Practice: A Journey from Pathophysiological to Therapeutic Aspects

Mercadante,

Bellastella

2024

Life

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This review was aimed at collecting the knowledge on the pathophysiological and clinical aspects of endocrine rhythms and their implications in clinical practice, derived from the published literature and from some personal experiences on this topic. We chose to review, according to the PRISMA guidelines, the results of original and observational studies, reviews, meta-analyses and case reports published up to March 2024. Thus, after summarizing the general aspects of biological rhythms, we will describe the characteristics of several endocrine rhythms and the consequences of their disruption, paying particular attention to the implications in clinical practice. Rhythmic endocrine secretions, like other physiological rhythms, are genetically determined and regulated by a central hypothalamic CLOCK located in the suprachiasmatic nucleus, which links the timing of the rhythms to independent clocks, in a hierarchical organization for the regulation of physiology and behavior. However, some environmental factors, such as daily cycles of light/darkness, sleep/wake, and timing of food intake, may influence the rhythm characteristics. Endocrine rhythms are involved in important physiological processes and their disruption may cause several disorders and also cancer. Thus, it is very important to prevent disruptions of endocrine rhythms and to restore a previously altered rhythm by an early corrective chronotherapy.

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L-Dopa Stimulated Growth Hormone Release in the Blind

Cited by 19 publications

References 12 publications

Effect of Oral Administration of Melatonin on Gh Responses to GRF 1–44 in Normal Subjects

Effect of Oral Administration of Melatonin on Gh Responses to GRF 1–44 in Normal Subjects

Melatonin and the pituitary‐thyroid axis status in blind adults: a possible resetting after puberty

Chrono-Endocrinology in Clinical Practice: A Journey from Pathophysiological to Therapeutic Aspects

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