Melatonin actions on ovaprim (synthetic GnRH and domperidone)-induced oocyte maturation in carp

Abstract

The major objective of the present study was to demonstrate the actions of exogenous melatonin on ovaprim (synthetic GnRH and domperidone)-induced final oocyte maturation focusing on the oxidative status of pre-ovulatory follicles in the carp Catla catla. Accordingly, gravid carp during the early spawning phase of the reproductive cycle were injected with melatonin and/or ovaprim at different time intervals or luzindole (a pharmacological blocker of melatonin receptors) before their administration. We studied their effects on the latency period, the rate of germinal vesicle breakdown (GVBD; a visual marker of final oocyte maturation) in oocytes, and the levels of maturation-promoting factor (MPF), as well as oxidative stress, different antioxidants, melatonin and MT1 melatonin receptor protein in the extracts of pre-ovulatory follicles. Notably, melatonin treatment 2 h before the injection of ovaprim resulted in the shortest latency period as well as the highest rate of GVBD and MPF formation. Exogenous melatonin, irrespective of the injection schedule, caused a significant reduction in intra-follicular oxidative stress and an increase in the levels of both enzymatic and nonenzymatic antioxidants, melatonin and its receptor protein. Concentrations of ovarian melatonin in each fish exhibited a significant negative correlation with the level of oxidative stress, but a positive correlation with the rate of GVBD and the activity/level of different antioxidants. However, no significant effects of melatonin and/or ovaprim were detected in luzindole-pretreated carp. Collectively, the present study provides the first evidence that melatonin pretreatment in carp ameliorates ovaprim actions on the process of final oocyte maturation by the formation of MPF and alleviates oxidative stress in pre-ovulatory follicles by stimulating different antioxidants.

Change in redox state and heat shock protein expression in an Indian major carp <i>Cirrhinus cirrhosus</i> exposed to zinc and lead

“…Stress has often been found to induce changes in the expression of antioxidative enzymes in fish (Moniruzzaman et al, 2016). In particular, SOD catalyzes the reaction of dismutation of superoxide to O 2 and H 2 O 2 , and is considered to play key roles in the first step of the enzymatic antioxidative defense system (Zelko et al, 2002).…”

“…The protein content of the samples was measured on 12.5% Laemmli SDS-PAGE and immunoblotted on the PVDF membrane following a wet electroblotting method (Moniruzzaman et al, 2016). The primary antibody (1:1000 dilution) was raised against a peptide corresponding to HSP70 / HSP90.…”

“…The PVDF membranes were incubated separately with the primary antibody, followed by incubation with the respective secondary antibody (dilution 1:500). Densitometric scanning was performed to quantify individual band intensity of each immunoblot using ImageJ Software (Moniruzzaman et al, 2016).…”

“…Tissues were homogenized with Tris buffered saline (10 mM Tris-HCl, 0.1 mM EDTA-2Na, 10 mM sucrose, 0.8% NaCl, pH 7.4), centrifuged and supernatant was used to measure levels of different enzymatic and non-enzymatic antioxidants such as malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GRd), glutathione peroxidise (GPx), glutathione S-transferase (GST) according to standard methods described earlier (Moniruzzaman et al, 2016).…”

Towards a physiological response of fishes under variable environmental conditions: An approach through neural network

“…The samples were compared using ANOVA; different alphabet on respective bar denotes significant differences between the values at p < 0.05. The number of data used to calculate the means were: n = 12. catalase (CAT), glutathione reductase (GRd), glutathione peroxidise (GPx), glutathione S-transferase (GST)] and non-enzymatic antioxidants [malondialdehyde (MDA) glutathione (GSH)], according to standard methods described previously (Moniruzzaman et al, 2016). In brief, the concentration of MDA equivalents was measured in the by thiobarbituric acid reactive substances (TBARS) assay with slight modifications.…”