Concentrations of plasma melatonin and luteinizing hormone in domestic gilts reared under artificial long or short days

Paterson, Andrew M.; Martin, G. B.; Foldes, A.; Maxwell, Colin A.; Pearce, G.P.

doi:10.1530/jrf.0.0940085

Cited by 43 publications

(35 citation statements)

References 23 publications

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“…Recently, we have shown that domestic gilts display a diurnal variation in plasma melatonin concentration (Paterson et al, 1992) which is similar to that observed in other species that use melatonin for this purpose (Lincoln et al, 1982;Arendt, 1986). The pattern of plasma melatonin we observed in the dark phase, with peak concentrations measured 1-2 h after lights off followed by a gradual decline towards baseline, was almost identical to that reported for European wild pigs (Mauget et al, 1990).…”

Section: Introductionsupporting

confidence: 83%

“…Reproductive activity in this species exhibits a high degree of seasonality, which is controlled by photoperiod (Mauget, 1982) and, as in other species, the diurnal variation in melatonin is believed to be the means by which photoperiodic information is transduced. The findings of Paterson et al (1992) suggest that this physiological mechanism also operates in domestic pigs.…”

Section: Introductionmentioning

confidence: 73%

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Seasonal inhibition of puberty in domestic gilts is overcome by melatonin administered orally, but not by implant

Paterson

Maxwell²,

Foldes³

1992

Reproduction

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The ability of exogenous melatonin, applied either orally or by implant, to overcome the seasonal inhibition of puberty in domestic gilts was tested in two experiments. In Expt 1, 24 gilts received two melatonin implants at 126 days of age and again at 161 days and 196 days, while 24 gilts acted as controls. All gilts were slaughtered at a mean age of 223 days. Blood samples were collected by venepuncture from eight gilts in each treatment at 126, 144 and 178 days of age and the plasma was assayed for melatonin concentration by direct radioimmunoassay. In Expt 2A, four gilts (125 days of age) were fed either 0, 1, 2 or 4 mg of melatonin at 14:00 h on each of four consecutive days. Blood samples for melatonin assay were collected via indwelling jugular catheters every 30 or 60 min from 12:00 to 22:00 h. In Expt 2B, 27 gilts were fed 1 mg of melatonin at 15:00 h each day from 129 days of age until slaughter at 221 days, while 25 gilts acted as controls. In both experiments, the presence of morphologically normal corpora lutea at slaughter was the criterion for puberty. In Expt 1, constant-release melatonin implants had no effect on the percentage of gilts which reached puberty. Among the 24 control gilts, two (8.3%) reached puberty compared with one of the 24 (4.2%) gilts with implants. In all the samples from control gilts, and in the samples taken from treated gilts prior to implantation at 126 days of age, mean plasma melatonin concentration was below the sensitivity of the assay (3.6 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Introductionsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 73%

Seasonal inhibition of puberty in domestic gilts is overcome by melatonin administered orally, but not by implant

Paterson

Maxwell²,

Foldes³

1992

Reproduction

Self Cite

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“…The inverse relationship between photoperiod and the length of the nocturnal peak concentration of melatonin in the pineal and in serum has been demonstrated in a number of species [8,[22][23][24][25]. In sheep, it has also been shown that systemic infusions that restore a rhythm of melatonin in the blood of pinealectomized animals can also induce neuroendocrine responses characteristic of long or short photoperiods [8].…”

Section: Discussionmentioning

confidence: 99%

Testicular Regression in Pinealectomized Syrian Hamsters following Infusions of Melatonin Delivered on Non-Circadian Schedules1

Grosse

Maywood

Ebling

et al. 1993

Biology of Reproduction

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The aims of this study were to validate the use of a timed infusion protocol for restoring physiologically appropriate rhythms of melatonin in the circulation of pinealectomized hamsters and, using such infusions, to compare the relative importance of the parameters of the nocturnal melatonin signal--frequency, phase, and duration of the interval between signals--in the photoperiodic control of testicular function in male Syrian hamsters. Hamsters were pinealectomized and fitted with a chronic s.c. cannula enabling them to receive timed infusions of melatonin (50 ng/h) or saline vehicle (50 microliters/h). In experiment 1, RIA of serum samples confirmed that s.c. infusions produced a pattern of melatonin in the blood equivalent in amplitude and duration to that observed previously in pineal-intact animals exposed to a short photoperiod. In experiment 2, we investigated the relative importance of the frequency of the melatonin signal and the duration of the interval between signals. Pinealectomized animals that received infusions of saline for 6 wk had large testes and high concentrations of LH in the serum. Animals that received a series of short-day-like infusions of melatonin of 14-h duration, separated by an interval of either 10 h or 6 h, underwent gonadal regression and had low serum concentrations of LH. Animals that received infusions of melatonin of 8-h duration, separated by intervals of 12 h, also exhibited full gonadal collapse. However, animals that received the same 8-h infusions separated by intervals of 8 h (i.e., once every 16 h) did not undergo gonadal regression and their circulating levels of LH remained high.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…Melatonin concentration in the medium samples was measured by a direct RIA with the use of Prospect 6C antiserum (Paterson et al 1992) and 3 H-melatonin according to the previously described and validated procedure (Fraser et al 1983, Prusik 2005.…”

Section: Melatonin Radioimmunoassaymentioning

confidence: 99%

Regulation of melatonin secretion in the pineal organ of the domestic duck – an in vitro study

Prusik¹,

Lewczuk²,

Ziółkowska³

et al. 2015

Polish Journal of Veterinary Sciences

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The aim of study was to determine the mechanisms regulating melatonin secretion in the pineal organs of 1-day-old and 9-month-old domestic ducks. The pineals were cultured in a superfusion system under different light conditions. Additionally, some explants were treated with norepinephrine.The pineal glands of 1-day-old ducks released melatonin in a well-entrained, regular rhythm during incubation under a 12 hrs light : 12 hrs dark cycle and adjusted their secretory activity to a reversed 12 hrs dark : 12 hrs light cycle within 2 days. In contrast, the diurnal changes in melatonin secretion from the pineals of 9-month-old ducks were largely irregular and the adaptation to a reversed cycle lasted 3 days. The pineal organs of nestling and adult ducks incubated in a continuous light or darkness secreted melatonin in a circadian rhythm. The treatment with norepinephrine during photophases of a light-dark cycle resulted in: 1) a precise adjustment of melatonin secretion rhythm to the presence of this catecholamine in the culture medium, 2) a very high amplitude of the rhythm, 3) a rapid adaptation of the pineal secretory activity to a reversed light-dark cycle. The effects of norepinephrine were similar in the pineal organs of nestlings and adults.In conclusion, melatonin secretion in the duck pineal organ is controlled by three main mechanisms: the direct photoreception, the endogenous generator and the noradrenergic transmission. The efficiency of intra-pineal, photosensitivity-based regulatory mechanism is markedly lower in adult than in nestling individuals.

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Concentrations of plasma melatonin and luteinizing hormone in domestic gilts reared under artificial long or short days

Cited by 43 publications

References 23 publications

Seasonal inhibition of puberty in domestic gilts is overcome by melatonin administered orally, but not by implant

Seasonal inhibition of puberty in domestic gilts is overcome by melatonin administered orally, but not by implant

Testicular Regression in Pinealectomized Syrian Hamsters following Infusions of Melatonin Delivered on Non-Circadian Schedules1

Regulation of melatonin secretion in the pineal organ of the domestic duck – an in vitro study

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