Effects of photoperiod on the secretion of growth hormone in female goats

Jin, Jin; Yaegashi, Tomoyoshi; Sawai, Ken; Hashizume, Takumi

doi:10.1111/j.1740-0929.2011.00998.x

Cited by 12 publications

(33 citation statements)

References 37 publications

(79 reference statements)

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“…Therefore, the present results where lactating goats were exposed to 16 h light resulted, as in these previous studies, in increased plasma IGF-1 levels. Therefore, as long days increased the GH secretion in female goats (Jin et al 2012), we can suppose that in the present study the increased plasma IGF-1 concentration is a result of increased GH secretion. Indeed, GH stimulates IGF-1 production in the liver, thus resulting in the increased plasma IGF-1 levels (Kendall et al 2003).…”

Section: Discussionsupporting

confidence: 53%

Effects of exposure to artificial long days on milk yield, maternal insulin‐like growth factor 1 levels and kid growth rate in subtropical goats

Hernández

Flores

Delgadillo

et al. 2015

Animal Science Journal

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This study was designed to determine whether any relationship exists between exposure to artificial long days, milk yield, maternal plasma insulin-like growth factor 1 (IGF-1) levels, and kid growth rate in goats. One group of lactating goats was maintained under naturally decreasing day length (control group; n = 19), while in another one, they were kept under artificial long days (LD group; n = 19). Milk yield was higher in goats from the LD group than that in the control group (P < 0.05). Maternal IGF-1 levels at day 57 of lactation were higher (P < 0.05) in goats from the LD group than the levels in the control group and were positively correlated with the total milk yields per goat at days 43 and 57 of lactation (r = 0.77 and r = 0.84, respectively; P < 0.01). Daily weight gain at week 4 was higher (P < 0.01) in kids from the LD group than that in kids from the control group and was correlated with total and average IGF-1 maternal levels (r = 0.60 and r = 0.60, P < 0.05). It was concluded that submitting lactating goats to artificial long days increases milk yield, plasma IGF-1 maternal levels and the growth rate of the kids.

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Section: Discussionsupporting

confidence: 53%

Effects of exposure to artificial long days on milk yield, maternal insulin‐like growth factor 1 levels and kid growth rate in subtropical goats

Hernández

Flores

Delgadillo

et al. 2015

Animal Science Journal

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“…Melatonin has been implicated in gonadotropin regulation and more recently glucose metabolism/insulin sensitivity [12-15]. Recently, GH response to GH-releasing hormone and spontaneous GH secretion in sheep were demonstrated to be greater during a long versus short photoperiod, and GH amplitude was reduced by melatonin administration [16]. Effects of daylight hours on energy metabolism, other signaling at the level of the growth plate, or even GH secretion that were not identified in previous studies due to small numbers of patients evaluated may play a role.…”

Section: Discussionmentioning

confidence: 99%

Is there “seasonal” variation in height velocity in children treated with growth hormone? Data from the National Cooperative Growth Study

Shulman

Frane

Lippe³

2013

Int J Pediatr Endocrinol

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BackgroundGrowth rate In children is reported to have seasonal variability. There are fewer published data regarding seasonal variability while on growth hormone (GH) therapy, and none analyzing growth rate with respect to number of daylight hours.MethodsWe analyzed 11,587 3-month intervals in 2277 prepubertal children (boys ages 3–14 years, girls ages 3–12 years) with idiopathic GH deficiency from the National Cooperative Growth Study (NCGS) database. All were naive to recombinant human GH (rhGH) therapy. Data were submitted from 31 US study centers. Seasonal variation in height velocity (HV) was assumed to be associated with the average number of daylight hours during the interval of time over which HV was computed. Number of daylight hours was determined from the date of the measurement and the latitude of the study center. Other independent variables evaluated included: height standard deviation score (SDS) at the beginning of the interval, chronologic age at the beginning of the interval, time from the start of rhGH treatment to the middle of the interval, month of the year, body mass index SDS at the beginning of the interval, rhGH dose/kg, mother’s height SDS, father’s height SDS, and log base 10 of the maximum stimulated GH concentration.ResultsAll variables examined, except month of the year, correlated significantly with interval HV. There was significant “seasonal” variability at all latitudes, with summer annualized HV being greater than winter HV. This difference was greatest in the first year of therapy (0.146 cm/yr/daylight hour; P < 0.0001) but persisted in subsequent years (0.121 cm/yr/daylight hr; P < 0.0001). The difference increased with distance from the equator. Growth rate over the year was not different among the latitudes reflected in this North American study.ConclusionsThere is “seasonal” variation in growth of children on rhGH therapy that correlates with number of daylight hours. The effect is modest and is greatest in the first year of therapy. Annual growth rate appears to be equal in children among latitudes covered by the US consistent with exposure to an equal number of daylight hours over the year. The physiologic mechanism behind this seasonal variation is not yet understood.

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“…The present study was performed using a long photoperiod, which was previously shown to enhance the secretion of GH in male and female goats (Jin et al . , , b). We previously reported that the GH pulse amplitude was slightly bigger and the mean GH concentrations were significantly higher in the long photoperiod (16:8 L : D) than in the short photoperiod (8:16 L : D) (Jin et al .…”

Section: Discussionmentioning

confidence: 99%

“…We previously reported that the GH pulse amplitude was slightly bigger and the mean GH concentrations were significantly higher in the long photoperiod (16:8 L : D) than in the short photoperiod (8:16 L : D) (Jin et al . , , b). The present study was conducted under such enhanced GH secretory conditions.…”

Section: Discussionmentioning

confidence: 99%

“…We recently demonstrated that a long photoperiod enhanced the secretion of GH in goats (Jin et al . , , b), suggesting that a long photoperiod may influence the hypothalamic DAergic system to modulate the secretion of GH in goats. Therefore, the relationship between GH secretion and the hypothalamic DAergic system in goats under a long photoperiod should be examined in more detail.…”

Section: Introductionmentioning

confidence: 99%

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Effects of hypothalamic dopamine on growth hormone‐releasing hormone‐induced growth hormone secretion and thyrotropin‐releasing hormone‐induced prolactin secretion in goats

Jin

Hashizume

2014

Animal Science Journal

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The aim of the present study was to clarify the effects of hypothalamic dopamine (DA) on the secretion of growth hormone (GH) in goats. The GH-releasing response to an intravenous (i.v.) injection of GH-releasing hormone (GHRH, 0.25 μg/kg body weight (BW)) was examined after treatments to augment central DA using carbidopa (carbi, 1 mg/kg BW) and L-dopa (1 mg/kg BW) in male and female goats under a 16-h photoperiod (16 h light, 8 h dark) condition. GHRH significantly and rapidly stimulated the release of GH after its i.v. administration to goats (P < 0.05). The carbi and L-dopa treatments completely suppressed GH-releasing responses to GHRH in both male and female goats (P < 0.05). The prolactin (PRL)-releasing response to an i.v. injection of thyrotropin-releasing hormone (TRH, 1 μg/kg BW) was additionally examined in male goats in this study to confirm modifications to central DA concentrations. The treatments with carbi and L-dopa significantly reduced TRH-induced PRL release in goats (P < 0.05). These results demonstrated that hypothalamic DA was involved in the regulatory mechanisms of GH, as well as PRL secretion in goats.

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Effects of photoperiod on the secretion of growth hormone in female goats

Cited by 12 publications

References 37 publications

Effects of exposure to artificial long days on milk yield, maternal insulin‐like growth factor 1 levels and kid growth rate in subtropical goats

Effects of exposure to artificial long days on milk yield, maternal insulin‐like growth factor 1 levels and kid growth rate in subtropical goats

Is there “seasonal” variation in height velocity in children treated with growth hormone? Data from the National Cooperative Growth Study

Effects of hypothalamic dopamine on growth hormone‐releasing hormone‐induced growth hormone secretion and thyrotropin‐releasing hormone‐induced prolactin secretion in goats

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