A transient ghrelin surge occurs just before feeding in a scheduled meal-fed sheep

Sugino, Toshihisa; Hasegawa, Yoshihisa; Kikkawa, Yuichiro; Yamaura, Junji; Yamagishi, Masako; Kurose, Yohei; Kojima, Masayasu; Kangawa, Kenji; Terashima, Yoshiaki

doi:10.1016/s0006-291x(02)00654-x

Cited by 172 publications

(116 citation statements)

References 20 publications

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“…Ghrelin stimulates GH secretion and promotes wakefulness, weight gain, and adrenocorticotropic hormone and cortisol release in humans and rodents (Frieboes et al, 1995;Wren et al, 2000;Diano et al, 2006;Szentirmai et al, 2007). Peripheral ghrelin levels rise sharply before main meals and decrease once the animal has been fed, most strikingly under restricted feeding conditions (Sugino et al, 2002;Kalra et al, 2003;Bodosi et al, 2004). Under fasting conditions, plasma ghrelin peaks match the previous pattern of daily meals in humans (Natalucci et al, 2005).…”

Section: Introductionmentioning

confidence: 88%

Ghrelin Effects on the Circadian System of Mice

Yannielli

Molyneux²,

Harrington³

et al. 2007

J. Neurosci.

120

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The orexigenic peptide ghrelin stimulates both food intake and growth hormone release and is synthesized in the stomach and in hypothalamic areas involved in feeding control. The suprachiasmatic nuclei of the hypothalamus (SCN) control most circadian rhythms, although there is evidence that some oscillators, such as food-entrainable oscillators, can drive activity rhythms even after SCN ablation. Ghrelin levels exhibit a circadian rhythm and closely follow feeding schedules, making this peptide a putative candidate for food-related entraining signals. We examined the response of the SCN to ghrelin treatments in vitro, by means of electrophysiological and bioluminescence recordings, and in vivo, by assessing effects on the phase of locomotor activity rhythms. Ghrelin applied at circadian time 6 in vitro to cultured SCN slices induced an ϳ3 h phase advance. In addition, ghrelin phase advanced the rhythm of PER2::LUC (Period2::Luciferase) expression in cultured SCN explants from mPer2Luc transgenic mice. In vivo, intraperitoneal administration of ghrelin or a synthetic analog, growth hormone-releasing protein-6 (GHRP-6), to ad libitum fed animals failed to alter circadian phase. When injected after 30 h of food deprivation, GHRP-6 induced a phase advance compared with saline-injected animals. These results indicate that ghrelin may play a role in the circadian system by exerting a direct action on the SCN and that the system as a whole may become sensitive to ghrelin and other feeding-related neuropeptides under conditions of food restriction.

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Section: Introductionmentioning

confidence: 88%

Ghrelin Effects on the Circadian System of Mice

Yannielli

Molyneux²,

Harrington³

et al. 2007

J. Neurosci.

120

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“…Plasma hormone measurement: Plasma hormones were measured by the time-resolved fluoroimmunoassay (TR-FIA) method [31].…”

Section: Methodsmentioning

confidence: 99%

“…Plasma FSH and LH levels were measured according to a modified method described previously [31] using Europium (Eu)-labeled rat FSH or rat LH, and diluted anti-FSH or -LH rabbit serum, respectively.…”

Section: Methodsmentioning

confidence: 99%

Progression of the Dose-Related Effects of Estrogenic Endocrine Disruptors, an Important Factor in Declining Fertility, Differs between the Hypothalamo-Pituitary Axis and Reproductive Organs of Male Mice

Warita

Sugawara

Yue

et al. 2006

The Journal of Veterinary Medical Science

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ABSTRACT. For the purpose of investigation of working mechanisms in endocrine disruptors, we evaluated the dose-related effects of fetal and/or neonatal exposure to an estrogenic compound on the male reproductive organs in adult mice, particularly with respect to gene expression of steroidogenic acute regulatory protein (StAR). The pregnant ICR mice were given subcutaneous injections of 10 µg/day/ animal of diethylstilbestrol (DES) to subject the fetal mice to in utero exposure (IUE). Subsequently, the newborn male mice were subjected to neonatal exposure (NE) by treatment with vehicle or 0.1-10 µg/day/animal of DES. Fertility rates of each group were as follows: control, 100%; IUE only, 60%; IUE+NE 0.1 µg, 25%; IUE+NE 1 µg, 0%; IUE+NE 10 µg, 0%. In general histology, germ cell layers in the seminiferous tubules were thinned in the group of IUE+NE 10 µg. Hypoplasia of the Leydig cells, in which the staining intensity of eosin was diminished, was also observed in the groups of IUE+NE 0.1-10 µg. The androgen receptor (AR) and estrogen receptor alpha (ERα) immunoexpression in the Leydig cells of IUE+NE 1-10 µg was slightly lower than that in the controls. Longterm dysfunction of the hypothalamo-pituitary-testicular axis, including sustained hypoproduction of gonadotropin and testosterone, and altered expressions of steroid hormone receptors and StAR genes were observed. The hypothalamo-pituitary control of gonadotropin secretion may be affected by the smaller doses of estrogenic agents than the reproductive organs. Furthermore, the fertility rate in the male mice exposed to this estrogenic agent was closely correlated with the testosterone levels, and even more so with the rate-limiting factor of steroidogenesis, StAR. This finding suggests that endocrine disruptors have an important pronounced effect on StAR gene expression. KEY WORDS: diethylstilbestrol (DES), endocrine disruptors, fertility rate, fetal and/or neonatal exposure, steroidogenic acute regulatory protein (StAR).

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“…Hormone Assay: The concentrations of plasma growth hormone and insulin were measured by time-resolved immunofluorometric assay as previous reported [24]. The intra-assay coefficients of variation were 4.1% and 9.3%, respectively.…”

Section: Cowsmentioning

confidence: 99%

Changes in Peripheral Blood Mononuclear Cells after Calving in Lactating Cows with Serious Decrease of Body Weight before and after Calving

Ohtsuka

Kase

Ando

et al. 2008

The Journal of Veterinary Medical Science

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ABSTRACT. The aim of this study was to clarify the hormonal and immunological changes in periparturient dairy cows with excessive weight loss following calving. We analyzed leukocyte populations and the peripheral blood mononuclear cell (PBMC) mRNA of IFN-γ, IL-4, growth hormone (GH)-receptor (R) and insulin -R and measured the GH and insulin concentrations. Ten dairy cows fed in one herd were used in this study and were divided into two groups. Five cows that experienced loss of body weight following calving of over 10% comprised the Weight Loss Group, and the remaining five cows, which experienced loss of body weight of 5% or less fol-

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A transient ghrelin surge occurs just before feeding in a scheduled meal-fed sheep

Cited by 172 publications

References 20 publications

Ghrelin Effects on the Circadian System of Mice

Ghrelin Effects on the Circadian System of Mice

Progression of the Dose-Related Effects of Estrogenic Endocrine Disruptors, an Important Factor in Declining Fertility, Differs between the Hypothalamo-Pituitary Axis and Reproductive Organs of Male Mice

Changes in Peripheral Blood Mononuclear Cells after Calving in Lactating Cows with Serious Decrease of Body Weight before and after Calving

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