Electrical Responses of Pineal Cells to Thyroid Hormones and Parathormone

Semm, P.; Demaine, C.; Vollrath, Lutz

doi:10.1159/000123231

Cited by 21 publications

(8 citation statements)

References 24 publications

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“…Significantly more inhibitory re sponses to T4 were found when the cells were tested during the night than when tested during the day. Although other substances, for example thyrocalcitonin and parathor mone, were also found to influence electrical activity of cells in the pineal gland, the findings of Semm et al [97] are consistent with the original hypothesis of Miline [60] of a feedback loop between the pineal and the thyroid glands. The effects of T4 on pineal responses may reflect a general effect of thyroid hormones on target organs of the sympa thetic nervous system.…”

supporting

confidence: 76%

“…More direct studies of endo crine organ ablation showed that hypophysectomy, thyroid ectomy, and adrenalectomy (but not orchiectomy) were found to result in small, but significant, reductions of the nighttime elevation of melatonin in the pineal gland of male rats [90], Variations in the nighttime elevation of melatonin were also reported to occur during the rat estrous cycle [43]. T4 and T3 have been reported to stimulate both basal and noradrenaline-induced increases in melatonin production [68], In a microelectrophoretic study Semm et al [97] found that T4 influenced the electrical activity of cells in the pineal gland of guinea pigs. Significantly more inhibitory re sponses to T4 were found when the cells were tested during the night than when tested during the day.…”

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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supporting

confidence: 76%

mentioning

confidence: 99%

Evidence for Pineal Gland Modulation of the Neuroendocrine-Thyroid Axis

Vriend¹

1983

Neuroendocrinology

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“…Only one of the two putative Fra‐2 target genes that have been identified by the direct genetic approach used by Smith et al . (2001), namely the type II iodothyronine deiodinase (DII) gene which is thought to activate circulating iodothyronine at discrete sites of action (Semm et al . 1981), has been shown to be induced at night by a β‐adrenergic mechanism (Kamiya et al .…”

Section: Discussionmentioning

confidence: 99%

Adrenergic inducibility of AP‐1 binding in the rat pineal gland depends on prior photoperiod

Guillaumond

Becquet

Bosler

et al. 2002

Journal of Neurochemistry

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The main known function of the pineal gland in mammals is the temporal synchronization of physiological rhythms to seasonal changes of day length (photoperiod). In rat, the transcription factor activating protein-1 (AP-1) displays a circadian rhythm in its DNA binding in the pineal gland, which results from the rhythmic expression of Fra-2. We postulated that, if AP-1 is an important component of pineal gland functioning, then variations in photoperiodic conditions should lead to an adaptation of the AP-1 binding rhythm. Here we show that AP-1 binding patterns adapt to variations in lighting conditions, in the same way as the rhythm of arylalkylamine-N-acetyltransferase (AA-NAT) activity. This adaptation appeared to result from photoperiodic adaptation of the rhythmic fra-2 gene expression and was reflected by an adapted delay between the onset of night and the acrophase of the nocturnal peak. We further showed that photoperiodic adaptation of both the AP-1 binding and AA-NAT activity rhythms resulted from adapted changes in adrenergic inducibility of both variables at night onset. We finally provided evidence that AP-1 shared with the CREM gene encoding the transcriptional repressor protein inducible cAMP early repressor (ICER) the ability to be hypersensitive or subsensitive to adrenergic stimuli, depending on prior photoperiod.

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“…Another member of the group of selected candidates was DII, which is thought to activate circulating iodothyronine at discrete sites of action (41). The levels of DII mRNA and enzyme activity increase at night in the rat pineal gland (18,29).…”

Section: Discussionmentioning

confidence: 99%

Tissue-Specific Transgenic Knockdown of Fos-Related Antigen 2 (Fra-2) Expression Mediated by Dominant Negative Fra-2

Smith

Burke

Humphries

et al. 2001

Molecular and Cellular Biology

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Fos-related antigen 2 (Fra-2) is a member of the Fos family of immediate-early genes, most of which are rapidly induced by second messengers. All members of this family act by binding to AP-1 sites as heterodimeric complexes with other proteins. However, each appears to have a distinct role. The role and biology of Fra-2 are less well understood than those of its relatives c-Fos, Fra-1, and FosB; moreover, Fra-2 target genes remain largely unknown, as does the basis of its selective effects on transcriptional activity. To pursue these issues, we created a transgenic rat line (NATDNF2) in which a dominant negative fra-2 (DNF2) gene is strongly expressed in the pineal gland; tissue selectivity was achieved by putting the DNF2 gene under the control of the rat arylalkylamine N-acetyltransferase (AANAT) regulatory region, which targets gene expression to a very restricted set of tissues (pineal gland Ͼ Ͼ Ͼ Ͼ retina). Expression of AANAT is normally turned on after the onset of darkness in the rat; as a result, pineal DNF2 expression occurs only at night. This was associated with marked suppression of the nocturnal increase in fra-2 mRNA and protein levels, indicating that DNF2 expression inhibits downstream effects of Fra-2, including the maintenance of high levels of fra-2 gene expression. Analysis of 1,190 genes in the NATDNF2 pineal gland, including the AANAT gene, identified two whose expression is strongly linked to fra-2 expression: the genes encoding type II iodothyronine deiodinase and nectadrin (CD24).Fos-related antigen 2 (Fra-2) is a member of the Fos family of transcription factors (9,24,34

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Electrical Responses of Pineal Cells to Thyroid Hormones and Parathormone

Cited by 21 publications

References 24 publications

Evidence for Pineal Gland Modulation of the Neuroendocrine-Thyroid Axis

Evidence for Pineal Gland Modulation of the Neuroendocrine-Thyroid Axis

Adrenergic inducibility of AP‐1 binding in the rat pineal gland depends on prior photoperiod

Tissue-Specific Transgenic Knockdown of Fos-Related Antigen 2 (Fra-2) Expression Mediated by Dominant Negative Fra-2

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