Circadian Rhythm of Corticotropin-Releasing Activity in the Hypothalamus of Normal and Adrenalectomized Rats

Hiroshige, Tsutomu; Sakakura, Muneki

doi:10.1159/000121952

Cited by 71 publications

(23 citation statements)

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“…The peak in CRF content is reached at the time of maximum activity within the pituitary-adrenocortical system, that is, just prior to the time of lights off. These findings are in agreement with those of Hiroshige and Sakakura [9], but in contrast to those of Moldow and Fischman [21], who reported that CRF content as measured by radio-immunoassay was lower in the evening than in the morning. The neural inputs to the hypothalamus are essential for initiating changes in CRF secretion, as hypothalami removed prior to the time of max imum CRF secretion do not go on to produce the expected increase in CRF release.…”

Section: Discussionsupporting

confidence: 92%

“…In some studies, the peak of hypothalamic CRF con tent [9] and release [11] occurred late in the afternoon, where as in others, a morning peak in CRF content, both bioactive [6,25] and immunoreactive, [21], was reported. The work described in this paper was carried out in or der to establish whether the CRF activity of the hypothala mus shows circadian variation, and to test the responsive ness of the components of the hypothalamo-pituitaryadrenocortical axis to their trophic hormones at various times of the day.…”

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confidence: 91%

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Diurnal Variations in Responsiveness of the Hypothalamo-Pituitary-Adrenocortical Axis of the Rat

Nicholson¹,

Lin²,

Mahmoud³

et al. 1985

Neuroendocrinology

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Hypothalami, anterior pituitary gland segments and adrenal glands were removed from female Wistar-derived rats decapitated at various times of the day. Blood and tissue hormone concentrations were measured and the tissues challenged with appropriate stimuli in vitro. Both bioactive and immunoreactive corticotrophin-releasing factor (CRF) content of the hypothalami were significantly higher in the evening than in the morning, as was the basal release of bioactive CRF in vitro. The response of the hypothalami to serotonin or acetylcholine added in vitro did not change with time of day. Basal bioactive and immunoreactive adrenocorticotrophin (ACTH) release from the anterior pituitary gland was significantly increased in the evening, as was the response to synthetic ovine CRF in vitro. Plasma ACTH concentrations in intact rats given crude CRF (hypothalamic extract) in vivo were higher in the evening at all times after injection tested, but this difference was markedly reduced in animals with mediobasal hypothalamic lesions. Corticosterone released basally from adrenal glands in vitro was significantly increased in the evening and the response to added ACTH 1–24 was slightly enhanced. For adrenal glands removed from lesioned rats, the pattern was reversed, corticosterone release in vitro being lower in the evening for all doses of ACTH added. Similarly in vivo, in intact rats given ACTH 1–24, plasma corticosterone concentrations and corticosterone release in vitro from adrenal glands removed after the injection were higher in the evening. After the placement of basal hypothalamic lesions, the situation was reversed, the response to ACTH administration in vivo being greater in the morning. The peaks in plasma concentrations of ACTH and corticosterone occurred 1 h later than the peak in hypothalamic CRF release. Therefore, it appears that the timing of the diurnal variation in plasma levels is dictated by the hypothalamus, but circadian changes in the output and responsiveness of the pituitary gland to CRF and the adrenal glands to ACTH play a major role in determining the amplitude of the rhythm.

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Section: Discussionsupporting

confidence: 92%

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confidence: 91%

Diurnal Variations in Responsiveness of the Hypothalamo-Pituitary-Adrenocortical Axis of the Rat

Nicholson¹,

Lin²,

Mahmoud³

et al. 1985

Neuroendocrinology

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“…Conversely, impairment of resting-stage hypothalamic OXT release mediates diurnal feeding arrhythmicity to cause obesity. We recognize that several other PVN neuropeptides, such as vasopressin, thyrotropin-releasing hormone, corticotropin-releasing factor, and somatostatin, were known to have diurnal rhythmicity (5,21,22,24). While the primary actions of these neuropeptides are to control various physiological activities other than feeding, they may secondarily contribute to the action of OXT in the regulation of metabolic rhythmicity.…”

Section: Discussionmentioning

confidence: 99%

“…Our attention was directed to the PVN because it represents the converging site that integrates the metabolic regulatory neurons in the arcuate nucleus (3,18) and the circadian pacemaker neurons in the suprachiasmatic nucleus (23,49). Although diurnal rhythmicity of several PVN neuropeptides, such as vasopressin, thyrotropin-releasing hormone, corticotropin-releasing factor, and somatostatin, were documented in the literature (5,21,22,24), the primary actions of these neuropeptides are to control various physiological activities other than feeding. Interestingly, we found that OXT, a PVN neuropeptide that we recently found to critically regulate feeding and body weight (56), exhibited diurnal rhythmicity in mice.…”

Section: Feeding Circadian Rhythm Affects Body Weight Independently Omentioning

confidence: 99%

Circadian intervention of obesity development via resting-stage feeding manipulation or oxytocin treatment

Zhang

Cai

2011

American Journal of Physiology-Endocrinology and Metabolism

145

204

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Zhang G, Cai D. Circadian intervention of obesity development via resting-stage feeding manipulation or oxytocin treatment. Am J Physiol Endocrinol Metab 301: E1004 -E1012, 2011. First published August 9, 2011; doi:10.1152/ajpendo.00196.2011.-The obesity pandemic can be viewed as a result of an imbalanced reaction to changing environmental factors. Recent research has linked circadian arrhythmicity to obesity and related diseases; however, the underlying mechanisms are still unclear. In this study, we found that high-fat diet (HFD) feeding strikingly promoted daytime rather than nighttime caloric intake in mice, leading to feeding circadian arrhythmicity. Using scheduled feeding with a defined amount of daily HFD intake, we found that an increase in the ratio of daytime to nighttime feeding promoted weight gain, whereas a decrease of this ratio rebalanced energy expenditure to counteract obesity. In identifying the underlying mechanism, we found that hypothalamic release of anorexigenic neuropeptide oxytocin displayed a diurnal rhythm of daytime rise and nighttime decline, which negatively correlated with the diurnal feeding activities of normal chow-fed mice. In contrast, chronic HFD feeding abrogated oxytocin diurnal rhythmicity, primarily by suppressing daytime oxytocin rise. Using pharmacological experiments with hypothalamic injection of oxytocin or oxytocin antagonist, we showed that daytime manipulation of oxytocin can change feeding circadian patterns to reprogram energy expenditure, leading to attenuation or induction of obesity independently of 24-h caloric intake. Also importantly, we found that peripheral injection of oxytocin activated hypothalamic oxytocin neurons to release oxytocin, and exerted metabolic effects similar to central oxytocin injection, thus offering a practical clinical avenue to use oxytocin in obesity control. In conclusion, resting-stage oxytocin release and feeding activity represent a critical circadian mechanism and therapeutic target for obesity.oxytocin; obesity; feeding; circadian OBESITY IS AN OUTCOME OF IMBALANCED interactions between environmental factors and the body's metabolic regulation (13,38). Recent research has established that the hypothalamus in the brain plays an essential role in the regulation of appetite and body weight balance (9,17,37,44,57). The underlying molecular basis involves hormone-dependent and nutrientdependent pathways in the mediobasal hypothalamus (1,3,4,9,12,17,25,29,37,44). In addition to metabolic regulation, the hypothalamus governs the circadian rhythms of various physiological activities, primarily dictated by the circadian pacemaker in the hypothalamic suprachiasmatic nucleus (14,40,51,52). The circadian pace in this hypothalamic region is predominantly exerted by the Clock-directed transcriptiontranslation oscillation loop (16,20,52), which can synchronize the physiological activities of various organs, including peripheral metabolic tissues (2, 53, 54). A recent study revealed that knockout of the Clock gene led to the prominent met...

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“…It has been reported to depress CRF production in the hypothalamus of stressed rats without altering the pituitary sensitivity to a hypothalamic extract with CRF activity [Hedge and Smelik, 1969;T akebe et al, 1971]. Moreover, animals blocked by dexamethasone have been largely used for determinations of corticotropin-releasing activity of hypothalamic extracts [Arimura et al, 1967;Hiroshige et al, 1968aHiroshige et al, , b, 1969Hiroshige andSato, 1970, 1971; H iroshige and Sakakura, 1971; Zarrow et al, 1972]. An implant of dexamethasone in the rat median eminence produced pituitary and adrenal atrophy and prevented the stressinduced rise in plasma corticosterone [Davidson et al, 1968], In contrast, others found that dexamethasone had an inhibitory effect at the pituitary level: it abolished ACTH release induced by CRF both in vivo [de Wied, 1964;Arimura et al, 1969;D avid-N elson and Brodish, 1969;Russel et al, 1969] and in vitro [Arimura et al, 1969;Berthold et al, 1970].…”

Section: Discussionmentioning

confidence: 99%

Sites of the Negative Feedback Action of Corticosteroids on the Hypothalamo-Hypophisial System of the Rat Fetus

Dupouy¹

1974

Neuroendocrinology

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Dexamethasone, corticosterone and deoxycorticos-terone were given to intact, encephalectomized or decapitated rat fetuses from mothers treated with metyrapone, in order to deter-mine the location of the sites of the negative feedback action of corticosteroids. The corticosterone concentration dropped in the adrenals and plasma of intact fetuses, measured on the 22nd day of pregnancy (21-day-old fetuses), after metyrapone (30 mg) had been given to the mothers on the 21st day of pregnancy (20-day-old fetuses). Adrenal hypertrophy was observed in intact (35%) and encephalectomized (18%) but not in decapitated fetuses. Corticosterone acetate (100 µg) prevented adrenal hypertrophy in both intact and encephalectomized fetuses. Dexamethasone acetate (125 µg) prevented adrenal hypertrophy only in the intact fetuses. A high level of deoxycorticosterone acetate (600 µg) also prevented adrenal hypertrophy. These results are discussed. These data suggest that the pituitary as well as the hypothalamus and/or the upper nervous structures contain sites sensitive to the negative feedback action of corticosterone. They also point toward a hypothalamic site of action of dexamethasone.

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Circadian Rhythm of Corticotropin-Releasing Activity in the Hypothalamus of Normal and Adrenalectomized Rats

Cited by 71 publications

References 0 publications

Diurnal Variations in Responsiveness of the Hypothalamo-Pituitary-Adrenocortical Axis of the Rat

Diurnal Variations in Responsiveness of the Hypothalamo-Pituitary-Adrenocortical Axis of the Rat

Circadian intervention of obesity development via resting-stage feeding manipulation or oxytocin treatment

Sites of the Negative Feedback Action of Corticosteroids on the Hypothalamo-Hypophisial System of the Rat Fetus

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