Role of pituitary in the thyroid hypertrophy of pinealectomized rats

Houssay, Alberto B.; Pazo, Jorge H.

doi:10.1007/bf02144887

Cited by 25 publications

(10 citation statements)

References 9 publications

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“…Hypertrophy of the rat thy roid gland has also been reported after pinealectomy [23,40, 60,96]. Losada [56] found that the thyroid gland of pinealectomized rats had increased mitotic activity of the fol licular epithelial cells, increased height of the cells lining the follicles and a decreased amount of colloid in the follicles.…”

Section: Effects Of Pinealectomy On the Neuroendocrine-thyroid Axismentioning

confidence: 95%

“…This histological data suggested increased activity of the thyroid gland after pinealectomy. Although the histological changes were similar to those induced by TSH administra tion, one group of investigators considered the enlargement of the thyroid gland after pinealectomy to be independent of pituitary TSH [40,76]. They interpreted their studies as evidence that the pineal gland had a direct effect on the thy roid gland.…”

mentioning

confidence: 99%

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Evidence for Pineal Gland Modulation of the Neuroendocrine-Thyroid Axis

Vriend¹

1983

Neuroendocrinology

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Experiments with rats and hamsters have provided evidence for an inhibitory action of the pineal gland on the neuroendocrine-thyroid axis. While maintenance of these animals in short photoperiod results in reduced levels of circulating thyroxin (T4), pinealectomy restores the levels to normal. Recent studies suggest that an active pineal gland produces a substance which inhibits thyrotrophin-releasing hormone release from the hypothalamus. Several investigators have concluded that endogenous melatonin, produced in the pineal gland, could account for the inhibitory action of the pineal gland on blood T4 levels. Although melatonin administration has been reported to inhibit blood T4 levels in both rats and hamsters, under certain experimental conditions melatonin administration can be demonstrated to have a counter-antithy-rotrophic effect resulting in increased blood levels of T4 and thyrotrophin. Assay of blood levels of melatonin of rats and hamsters under various experimental conditions will be necessary to distinguish physiological from pharmacological effects of melatonin. Lesion studies as well as studies with melatonin implants in the brain, suggest that the site of action is in the anterior hypothalamus. The effects of melatonin on the neuroendocrine-thyroid axis are similar to its effects on the neuroendocrine-gonadal axis, leading to the hypothesis of a common site of action for the thyroid and gonadal effects of melatonin. Although many pineal ‘factors’ have been postulated to account for the action of this gland, an action of melatonin on the serotonergic system of the brain stem could account for the data.

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Section: Effects Of Pinealectomy On the Neuroendocrine-thyroid Axismentioning

confidence: 95%

mentioning

confidence: 99%

Evidence for Pineal Gland Modulation of the Neuroendocrine-Thyroid Axis

Vriend¹

1983

Neuroendocrinology

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“…This effect is prevented by pinealectomy. In contrast, pinealectomy induced thyroid hypertrophy, an effect reversed by melatonin [21,22]. Chronic night treatment with melatonin in the drinking water for mice significantly lowers night levels of T 3 and T 4 in peripheral blood [22].…”

Section: Discussionmentioning

confidence: 93%

The Effect of Melatonin on Liver Superoxide Dismutase Activity, Serum Nitrate and Thyroid Hormone Levels.

Öztürk

Coşkun²,

Erbaş³

et al. 2000

JJP

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“…Injection of melatonin prevented the development of thyroid hyperplasia in pinealectomized animals [12,21]. Injections of melatonin also smoothed methylthiouracyl-induced effects resulting in the development of goiter [22].…”

Section: Introductionmentioning

confidence: 96%

“…Later on, experiments with injections of melatonin into laboratory animals demonstrated that this hormone exerts significant effects on various links of the functioning of the hypothalamo-hypophyseal-thyroid axis (HHTA) [23]. It was found that melatonin injection leads to a considerable decrease in the mass of the thyroid gland [21,22], suppresses the absorption of 131 I by thyroid parenchyma [24,25], disturbs intrathyroid hormonogenesis toward the predominance of iodotyrosine above iodothyronine [8,26], decreases the rate of secretion of thyroid hormones [10,27,28] and the index of free Т 4 [29], significantly decreases the concentration of thyroid hormones circulating in the blood, and also decreases the relative level of saturation of thyroid-binding globulin. Although species-and age-related peculiarities, diurnal or seasonal alterations of illumination in the given experiment, as well as the doses of melatonin used and pathways of its injections, were noticeably reflected on the data of examination of the above aspects of the effects of exogenous melatonin, the data obtained allowed researchers to qualify the epiphysis and its main hormone melatonin as factors responsible for inhibition of thyroid activity.…”

Section: Introductionmentioning

confidence: 99%

Role of Melatonin in the Mechanisms Underlying Neuroendocrine Control of the Hypothalamo-Hypophyseal-Thyroid Axis

2008

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The authors of this review generalize and analyze the published data, as well as their own findings, related to melatonin-mediated interaction of the pineal gland (the brain epiphysis) with the hypothalamo-hypophysealthyroid axis (HHTA). The review deals with (i) historical aspect of development of the concepts on neuroendocrine mechanisms underlying the control of functions of the thyroid gland, (ii) data on circadian and seasonal rhythms of the functioning of the epiphysis and HHTA, (iii) basic facts about direct and feedback connections between the brain epiphysis and HHTA, and (iv) overview of the experimental data on age-related changes in the epiphysis-thyroid axis.

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Role of pituitary in the thyroid hypertrophy of pinealectomized rats

Cited by 25 publications

References 9 publications

Evidence for Pineal Gland Modulation of the Neuroendocrine-Thyroid Axis

Evidence for Pineal Gland Modulation of the Neuroendocrine-Thyroid Axis

The Effect of Melatonin on Liver Superoxide Dismutase Activity, Serum Nitrate and Thyroid Hormone Levels.

Role of Melatonin in the Mechanisms Underlying Neuroendocrine Control of the Hypothalamo-Hypophyseal-Thyroid Axis

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