What is the role of melatonin within the anterior pituitary?

Hazlerigg, David G.

doi:10.1677/joe.0.1700493

Cited by 47 publications

(33 citation statements)

References 75 publications

(69 reference statements)

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“…23 This sleepenhancing effect may be partly attributable to increased night-time melatonin levels, which have been found among practitioners of another stress reduction procedure, meditation. 24 Melatonin is thought to play an important role in regulating sleep-wake cycles, 25 and as noted earlier, NES subjects have been shown to have an attenuated nocturnal rise in melatonin. 6 Third, dysphoric mood has been reported among NES subjects, 1,6 and those in the present study who practiced APRT for 1 week showed significant drops in selfrated depression, anger, and fatigue.…”

Section: Discussionmentioning

confidence: 77%

Night eating syndrome: effects of brief relaxation training on stress, mood, hunger, and eating patterns

2003

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BACKGROUND: Night eating syndrome (NES) is characterized by a lack of appetite in the morning, consumption of 50% or more of daily food intake after 6:00 p.m., and difficulty falling and/or staying asleep. It has been associated with stress and with poor results at attempts to lose weight. OBJECTIVE: The purpose of this study was to determine whether a relaxation intervention (Abbreviated Progressive Muscle Relaxation Therapy, APRT) that has been shown to significantly reduce stress levels in normal, healthy adults would also benefit an NES sample. RESEARCH METHODS AND PROCEDURES: A total of 20 adults with NES were randomly assigned to either a relaxation training (APRT) or a Control (quietly sitting for the same amount of time) group, and all subjects attended two laboratory sessions 1 week apart. Pre-and postsession indices of stress, anxiety, relaxation, and salivary cortisol were obtained, as well as Day 1 and Day 8 indices of mood. Food diaries and hunger ratings were also obtained. RESULTS:The results indicated that 20 min of a muscle relaxation exercise significantly reduced stress, anxiety, and salivary cortisol immediately postsession. After practicing these exercises daily for a week, subjects exhibited lowered stress, anxiety, fatigue, anger, and depression on Day 8. APRT was also associated with significantly higher a.m. and lower p.m. ratings of hunger, and a trend of both more breakfast and less night-time eating. DISCUSSION: These data support the role of stress and anxiety in NES and suggest that practicing relaxation may be an important component of treatment for this condition.

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Section: Discussionmentioning

confidence: 77%

Night eating syndrome: effects of brief relaxation training on stress, mood, hunger, and eating patterns

2003

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“…Melatonin is exclusively secreted at night, and the duration of the melatonin signal corresponds to the duration of the dark period, thereby providing photoperiodic information to melatonin receptors (von Gall et al 2002). This indicates that melatonin has physiological functions in the PTand that the PT might play an important role in the mediation of seasonal or circadian signals (Hazlerigg 2001). In fact, the duration of the photoperiod affects the structure of TSH cells and TSHb mRNA expression in the PT cells of the Djungarian hamster (Bergmann et al 1989, Bockmann et al 1996, Arai & Kameda 2004.…”

Section: Introductionmentioning

confidence: 99%

Glutamine and glutamic acid enhance thyroid-stimulating hormone β subunit mRNA expression in the rat pars tuberalis

Aizawa¹,

Sakai²,

Sakata³

2012

Journal of Endocrinology

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Thyroid-stimulating hormone (TSH)-producing cells of the pars tuberalis (PT) display distinct characteristics that differ from those of the pars distalis (PD). The mRNA expression of TSHb and aGSU in PT has a circadian rhythm and is inhibited by melatonin via melatonin receptor type 1; however, the detailed regulatory mechanism for TSHb expression in the PT remains unclear. To identify the factors that affect PT, a microarray analysis was performed on lasercaptured PT tissue to screen for genes coding for receptors that are abundantly expressed in the PT. In the PT, we found high expression of the KA2, which is an ionotropic glutamic acid receptor (iGluR). In addition, the amino acid transporter A2 (ATA2), also known as the glutamine transporter, and glutaminase (GLS ), as well as GLS2, were highly expressed in the PT compared to the PD. We examined the effects of glutamine and glutamic acid on TSHb expression and aGSU expression in PT slice cultures. L-Glutamine and L-glutamic acid significantly stimulated TSHb expression in PT slices after 2-and 4-h treatments, and the effect of L-glutamic acid was stronger than that of L-glutamine. In contrast, treatment with glutamine and glutamic acid did not affect aGSU expression in the PT or the expression of TSHb or aGSU in the PD. These results strongly suggest that glutamine is taken up by PT cells through ATA2 and that glutamic acid locally converted from glutamine by Gls induces TSHb expression via the KA2 in an autocrine and/or paracrine manner in the PT.

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“…As this region differentiates into the adenohypophysis, melatonin receptors are transiently expressed in the pars distalis (PD) during late fetal development and then disappear over the initial 2-3 weeks of postnatal life (6). In contrast, MT 1 melatonin receptors remain expressed in the pars tuberalis (PT) into adulthood (7). Hence, there is developmental and tissue-specific control of melatonin receptor expression in the pituitary.…”

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confidence: 99%

Gonadotrophin-releasing hormone drives melatonin receptor down-regulation in the developing pituitary gland

Johnston

Messager

Ebling

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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Melatonin is produced nocturnally by the pineal gland and is a neurochemical representation of time. It regulates neuroendocrine target tissues through G-protein-coupled receptors, of which MT1 is the predominant subtype. These receptors are transiently expressed in several fetal and neonatal tissues, suggesting distinct roles for melatonin in development and that specific developmental cues define time windows for melatonin sensitivity. We have investigated MT 1 gene expression in the rat pituitary gland. MT1 mRNA is confined to the pars tuberalis region of the adult pituitary, but in neonates extends into the ventral pars distalis and colocalizes with luteinizing hormone ␤-subunit (LH␤) expression. This accounts for the well documented transient sensitivity of rat gonadotrophs to melatonin in the neonatal period. Analysis of an upstream fragment of the rat MT 1 gene revealed multiple putative response elements for the transcription factor pituitary homeobox-1 (Pitx-1), which is expressed in the anterior pituitary from Rathke's pouch formation. A Pitx-1 expression vector potently stimulated expression of both MT 1-luciferase and LH␤-luciferase reporter constructs in COS-7 cells. Interestingly, transcription factors that synergize with Pitx-1 to trans-activate gonadotroph-associated genes did not potentiate Pitx-1-induced MT 1-luciferase activity. Moreover, the transcription factor, early growth response factor-1, which is induced by gonadotrophinreleasing hormone (GnRH) and trans-activates LH␤ expression, attenuated Pitx-1-induced MT 1-luciferase activity. Finally, pituitary MT 1 gene expression was 4-fold higher in hypogonadal (hpg) mice, which do not synthesize GnRH, than in their wild-type littermates. These data suggest that establishment of a mature hypothalamic GnRH input drives the postnatal decline in pituitary MT 1 gene expression.

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What is the role of melatonin within the anterior pituitary?

Cited by 47 publications

References 75 publications

Night eating syndrome: effects of brief relaxation training on stress, mood, hunger, and eating patterns

Night eating syndrome: effects of brief relaxation training on stress, mood, hunger, and eating patterns

Glutamine and glutamic acid enhance thyroid-stimulating hormone β subunit mRNA expression in the rat pars tuberalis

Gonadotrophin-releasing hormone drives melatonin receptor down-regulation in the developing pituitary gland

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