The influence of exogenous melatonin on the seasonal patterns of ovulation and oestrus in sheep

Staples, L. D.; McPhee, S. R.; Kennaway, David J.; Williams, A.E.

doi:10.1016/0378-4320(92)90011-2

Cited by 46 publications

(18 citation statements)

References 25 publications

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“…The daily plasma melatonin pattern in Romney Marsh and Suffolk no-implanted ewes seems to be the same of those raised under natural or artificial conditions in lower, intermediate or higher latitudes in southern or northern hemispheres [2,16,21,30]. The melatonin treatment also produced a similar model of daily melatonin levels as re-ported previously by others (9,12,13,17,28,33,39], which is characterized by high plasma melatonin concentrations during the light phase of the day.…”

Section: Discussionsupporting

confidence: 77%

Plasma Melatonin and Progesterone Profiles of Suffolk and Romney Marsh Ewes Implanted with Melatonin during Anoestrus Season at Lower Latitudes in Southern Hemisphere

Sasa

Rodrigues

Nonaka

et al. 2016

Acta Scientiae. Vet.

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Background: The subcutaneous implants of melatonin are stimulatory and mimic the positive effects of short photoperiod on reproduction in small ruminants. This study investigated the daily plasma melatonin profiles in ewes treated with melatonin implants and kept under natural photoperiod in Southeastern Brazil. The plasma progesterone concentrations were also investigated before and after melatonin implantation.Materials, Methods & Results: Romney Marsh (n = 11) and Suffolk (n = 10) ewes, which had been isolated from rams for at least 2 months prior to the beginning of the trial, were randomly allocated in two groups based on melatonin implant treatment (with or without melatonin implant). For plasma melatonin concentration, 43 days after melatonin implantation and 3 days before the ram introduction blood samples were collected every 2 hours during 24 hours. For plasma progesterone concentrations, blood samples were collected every once to twice a week for 2 different periods: prior to melatonin implantation and 46 days after the melatonin implantation and at the same day of the introduction of rams. The hormonal concentrations were determined by the radioimmunoassay method (RIA). The data were analyzed according to MIXED procedure (SAS) as repeated measurements for random animal effects. The effect of melatonin treatment on plasma melatonin 24-h period varied according to the breed. At the dark-phase, there were no plasma melatonin differences (P > 0.05) between implanted and no-implanted (228.02 ± 58.39 vs. 169.59 ± 48.39) Romney Marsh ewes whereas for Suffolk ewes the plasma melatonin levels were higher in implanted (305.61 ± 68.39 pg/mL) than no-implanted (151.26 ± 38.35 pg/mL) ones. At the light-phase, melatonin treatment effects could be evidenced and these differences (P < 0.01) consisted of higher melatonin values for implanted ewes and basal values for no-implanted ones in both breed groups. Before the melatonin implantation, the plasma progesterone levels were ˂ 1 ng/mL for Romney Marsh (0.41 ± 0.02 ng/mL) and Suffolk (0.47 ± 0.02 ng/mL) ewes. During the ram introduction period, no melatonin treatment effect was observed on plasma progesterone concentrations in both breed groups, but 2 days after ram introduction the plasma progesterone concentrations increased the mean values > than 1 ng/mL in implanted and no-implanted Suffolk ewes. In implanted Romney Marsh ewes the elevation of progesterone mean values was weak whereas in no-implanted Romney Marsh ewes the progesterone levels were maintained ˂ 1 ng/mL during all the blood sample collection times.Discussion: The melatonin treatment also produced a similar model of daily melatonin levels as reported previously by others, which is characterized by high plasma melatonin concentrations during the light phase of the day. The effect of melatonin implants on plasma melatonin profiles interacted with breed confirming an individual response to melatonin implantation which is proportional to genetic individual variation pattern of melatonin secretion. Before the melatonin implantation all Romney Marsh and Suffolk ewes were judged to be in non-ovulatory period (anoestrus) with plasma progesterone mean values lower than 1 ng/mL. The melatonin treatment helped to induce the ovulatory activity in most of the ewes that were in anestrous at the time of melatonin implantation and the efficacy of this treatment depends on the individual variation in ovulatory response to ram introduction. In Southeastern Brazil., melatonin implant altered the daily plasma melatonin profiles of Suffolk and Romney Marsh ewes by increasing the melatonin levels during the light-phase of the day. Melatonin implant also induced an ovulatory response in Suffolk and Romney Marsh after the introduction of the rams. For no-implanted Suffolk ewes, the male effect is sufficient to provoke an ovulatory response.

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Section: Discussionsupporting

confidence: 77%

Plasma Melatonin and Progesterone Profiles of Suffolk and Romney Marsh Ewes Implanted with Melatonin during Anoestrus Season at Lower Latitudes in Southern Hemisphere

Sasa

Rodrigues

Nonaka

et al. 2016

Acta Scientiae. Vet.

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“…Indeed, when melatonin is administered to female sheep (ewes) during the time of year when they are not ovulating, it can actually promote the re‐initiation of ovulation and subsequent fertility. My group used these findings to develop a veterinary drug preparation of melatonin (Regulin; Ceva Animal Health Pty Ltd., Glenorie, NSW, Australia) that produces continuous levels of melatonin for more than 10 weeks in the night‐time physiological range and which is used to advance the start of the fertile period and increase their ovulation rate and offspring numbers . It is still available as a registered veterinary drug in Australia and elsewhere.…”

Section: What Does Melatonin Do?mentioning

confidence: 99%

Potential safety issues in the use of the hormone melatonin in paediatrics

Kennaway

2015

J Paediatrics Child Health

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Melatonin is a hormone produced by the pineal gland during the night in response to light/dark information received by the retina and its integration by the suprachiasmatic nucleus. When administered to selected populations of adults, in particular those displaying delayed sleep phase disorder, melatonin may advance the time of sleep onset. It is, however, being increasingly prescribed for children with sleep disorders despite the fact that (i) it is not registered for use in children anywhere in the world; (ii) it has not undergone the formal safety testing expected for a new drug, especially long-term safety in children; (iii) it is known to have profound effects on the reproductive systems of rodents, sheep and primates, as well as effects on the cardiovascular, immune and metabolic systems; and (iv) there is the potential for important interactions with drugs sometimes prescribed for children. In this review, I discuss properties of melatonin outside its ability to alter sleep timing that have been widely ignored but which raise questions about the safety of its use in infants and adolescents.

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“…The administration of melatonin, with different modalities, has shown to improve the reproductive efficiency in different sheep breeds, and subcutaneous implants are the most widely used both in Europe and in other continents (Chemineau et al, 1996;de Nicolo et al, 2009). The melatonin implants are able to mimic the short days, without causing an inhibition of pineal secretion of indoleamine, and stimulate reproductive activity in sheep (Staples et al, 1992). In dairy sheep, at Mediterranean latitudes, the advance of lambing at the beginning of Autumn is an essential condition for a duration of 6-7 months of lactation (Carcangiu et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Melatonin treatment in spring and reproductive recovery in sheep with different body condition score and age

Luridiana

Mura

Daga

et al. 2015

Animal Reproduction Science

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The influence of exogenous melatonin on the seasonal patterns of ovulation and oestrus in sheep

Cited by 46 publications

References 25 publications

Plasma Melatonin and Progesterone Profiles of Suffolk and Romney Marsh Ewes Implanted with Melatonin during Anoestrus Season at Lower Latitudes in Southern Hemisphere

Plasma Melatonin and Progesterone Profiles of Suffolk and Romney Marsh Ewes Implanted with Melatonin during Anoestrus Season at Lower Latitudes in Southern Hemisphere

Potential safety issues in the use of the hormone melatonin in paediatrics

Melatonin treatment in spring and reproductive recovery in sheep with different body condition score and age

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