Seasonal variations of melatonin in ram seminal plasma are correlated to those of testosterone and antioxidant enzymes

Abstract

Background: Some breeds of sheep are highly seasonal in terms of reproductive capability, and these changes are regulated by photoperiod and melatonin secretion. These changes affect the reproductive performance of rams, impairing semen quality and modifying hormonal profiles. Also, the antioxidant defence systems seem to be modulated by melatonin secretion, and shows seasonal variations. The aim of this study was to investigate the presence of melatonin and testosterone in ram seminal plasma and their variations between the breeding and nonbreeding seasons. In addition, we analyzed the possible correlations between these hormones and the antioxidant enzyme defence system activity. Methods:Seminal plasma from nine Rasa Aragonesa rams were collected for one year, and their levels of melatonin, testosterone, superoxide dismutase (SOD), glutathione reductase (GRD), glutathione peroxidase (GPX) and catalase (CAT) were measured.Results: All samples presented measurable quantities of hormones and antioxidant enzymes. Both hormones showed monthly variations, with a decrease after the winter solstice and a rise after the summer solstice that reached the maximum levels in October-November, and a marked seasonal variation (P < 0.01) with higher levels in the breeding season. The yearly pattern of GRD and catalase was close to that of melatonin, and GRD showed a significant seasonal variation (P < 0.01) with a higher activity during the breeding season. Linear regression analysis between the studied hormones and antioxidant enzymes showed a significant correlation between melatonin and testosterone, GRD, SOD and catalase. Conclusions:These results show the presence of melatonin and testosterone in ram seminal plasma, and that both hormones have seasonal variations, and support the idea that seasonal variations of fertility in the ram involve interplay between melatonin and the antioxidant defence system. BackgroundMelatonin plays a central role in fine-tuning circadian rhythms [1] and seasonal changes [2] through its daily nocturnal increase in the blood [3]. In seasonally breeding mammals that use changes in the photoperiod to time

Casa Parameters of Mithun Semen Treated with Melatonin

“…The improvement of semen quality due to addition of exogenous melatonin recorded in the present study was previously reported (Casao et al, 2010;Ashrafi et al, 2011;Ashrafi et al, 2013;Perumal et al, 2015). Moreover, the addition of exogenous melatonin was significantly improving the percentages of DNA morphology, sperm viability and intact plasma membrane (swelling tails) especially at the optimum (3 mM) level of melatonin was reported in the previous study Perumal et al, 2015).…”

“…Moreover, it reduced the production malondialdehyde and cholesterol efflux as preserved in liquid state Perumal et al, 2015). However, many authors reported that MT has beneficial effects on preservation of mammalian sperm and improves the velocity and mobility parameters of spermatozoa (Ashrafi et al, 2011;Ashrafi et al, 2013) and also on semen quality parameters (Casao et al, 2010;Ashrafi et al, 2011;Ashrafi et al, 2013;Perumal et al, 2015).…”

“…Melatonin has improved the velocity and mobility parameters of mithun semen in dose depended manner in different seasons (Casao et al, 2010;Perumal et al, 2015) as 3 mM MT is being the most effective and optimum concentration and spring and winter are more suitable seasons. Thus, melatonin in the sperm extender induced higher viability rates, a greater percentage of total motile and progressive motile spermatozoa, a larger number of sperm with higher medium or rapid velocity and elevated intracellular ATP concentrations as reported in the previous studies ; Perumal et al,…”

Management Factors Affecting Fertility in Sheep

“…Although seasonality is less marked in male than in female, changes in testicular volume, hormonal profiles, sexual behaviour and semen quality that affect the reproductive performance of rams have been reported (Casao, et al, 2010a). In this sense, the treatment of rams with slow release implants of melatonin during the non-breeding season accounted for increased scrotal diameter and improved the reproductive performance of ewes inseminated during anoestrus with semen from these melatonin-implanted males.…”

Functional aspects of seminal plasma and sperm proteins and their potential as molecularmarkers of fertility

“…GSHPx is one the main enzymes that protects sperm (Perry et al, 1992;Dacheux et al, 2005) and it catalyzes the reduction of hydrogen peroxide (Halliwell and Gutteridge, 1990). Increased GSPHx activity in ram semen is linked to antioxidant effects and maintenance of sperm viability (Casao et al, 2010). Another seminal plasma molecule known as acidic seminal fluid protein (aSFP) also has actions on the control of oxidative stress in the bovine reproductive tract (Einspanier et al, 1993;Schöneck et al, 1996).…”