Ajit Singh Mahla

Sustained delivery of exogenous melatonin influences biomarkers of oxidative stress and total antioxidant capacity in summer-stressed anestrous water buffalo (Bubalus bubalis)

High ambient temperature during summer in tropical and subtropical countries predisposes water buffaloes (Bubalus bubalis) to develop oxidative stress having antigonadotropic and antisteroidogenic actions. Melatonin is a regulator of seasonal reproduction in photoperiodic species and highly effective antioxidant and free radical scavenger. Therefore, a study was designed to evaluate the effect of sustained-release melatonin on biomarkers of oxidative stress i.e., the serum malondialdehyde (MDA) and nitric oxide (NO), and the total antioxidant capacity (TAC). For the study, postpartum buffaloes diagnosed as summer anestrus (absence of overt signs of estrus, concurrent rectal examination, and RIA for serum progesterone) were grouped as treated (single subcutaneous injection of melatonin at 18 mg/50 kg body weight dissolved in sterilized corn oil as vehicle, n = 20) and untreated (subcutaneous sterilized corn oil, n = 8). Blood sampling for estimation of serum TAC and MDA (mmol/L) and NO (μmol/L) was carried out at 4 days of interval from 8 days before treatment till 28 days after treatment or for the ensuing entire cycle length. Results showed serum TAC concentration was higher in the treatment group with a significant (P < 0.05) increasing trend, whereas MDA and NO revealed a significant (P < 0.05) decline. Serum MDA and NO were higher in control compared with those of treatment group. Moreover, buffaloes in the treatment group showed 90% estrus induction with 18.06 ± 1.57 days mean interval from treatment to the onset of estrus. These results report that melatonin has a protective effect by elevating antioxidant status and reducing oxidative stress resulting in the induction of cyclicity in summer-stressed anestrous buffaloes.

Supplementation of Slow‐Release Melatonin Improves Recovery of Ovarian Cyclicity and Conception in Summer Anoestrous Buffaloes (Bubalus bubalis)

The role of melatonin as a protective neurohormone against restoring cyclicity in summer anoestrous animals in photoperiod species has gained wider acceptance. This study was designed to uncover the evidence the slow-release melatonin (MLT) has on initiation of ovarian cyclicity and conception rate (CR) in summer anoestrous buffaloes. Thus, buffaloes diagnosed as summer anoestrous (absence of overt signs of oestrus, concurrent rectal examination and radioimmunoassay for serum progesterone at 10 days interval) were grouped as untreated (Group I, sterilized corn oil, n = 8) and treated (Group II, single subcutaneous injection of MLT @18 mg/50 kg bwt in sterilized corn oil, n = 20). Animals treated and detected in oestrus were artificially inseminated (AI) followed by division into Group III (second dose of MLT on 5th day post-AI, n = 8) and Group IV (no melatonin administration, n = 10). Blood samples were collected at 4 days interval for estimation of serum MLT, progesterone and oestrogen using radioimmunoassay kit. Mean oestrous induction rate (OIR), oestrous induction interval (OII), interoestrous interval (IOI) and CR were estimated. Compared to control, concentration of melatonin was significantly (p < 0.05) higher in treated group ranging from 14.34 ± 1.72 to 412.31 ± 14.47 pg/ml whereas other two hormones did not show any concentration difference. Melatonin-administered buffaloes showed significantly (p < 0.05) higher (90%) OIR with OII of 18.06 ± 1.57 days. Results showed improvement in conception rate in buffaloes administered with post-insemination melatonin. It can be concluded from the study that slow-release melatonin supplementation restored cyclicity in summer anoestrous animals resulting in improvement in conception rate in buffaloes.

Effect of dietary n-3 polyunsaturated fatty acid rich fish oil on the endometrial prostaglandin production in the doe (Capra hircus)

Recently, we showed that dietary supplementation of n-3 PUFA rich fish oil (FO) decreased the metabolites of serum prostaglandin (PG) F2α and E2 during the window of pregnancy recognition in the doe. In this study, we investigated its effect on the changes on endometrial PG production in vitro. Cycling does (n = 12) of Rohilkhand region were divided into two equal groups and fed a concentrate diet supplemented with either FO containing 26% n-3 PUFA (TRT; n = 6) or palm oil (CON; n = 6) @ 0.6 mL/kg body weight for 57 days. Estrus was synchronized by two injections of PGF2α analogue viz, on day 25 and 36 of supplementation and laparo-hysterotomy was performed to obtain endometrial tissue on day 16 of the synchronized estrus. Endometrial explant culture was done using a defined medium.The basal PG production was assayed at 6 and 12 h. Endometrial explant was stimulated with oxytocin (OXT) and/or recombinant ovine interferon tau (roIFN-τ) and PGs were assayed at 3 and 12 h post-treatment. The relative expression of genes related to PG metabolism in the endometrium was done by Quantitative Real Time PCR technique (qRT-PCR). There was a significant (P < 0.05) decline in the basal production of PGF2α and PGE2 in the TRT as compared to the CON group. The cultured endometrial tissue produced PGF2α in a time- dependent fashion in both the groups (P < 0.05). Neither OXT nor roIFN-τ had a significant (P > 0.05) effect on the PGF2α and PGE2 production in the TRT group. Similarly, the PG production in the OXT and roIFN-τ was comparable with the control in TRT. Expression of mRNA for cyclooxygenase-2 (COX-2), cytosolic phospholipase A2 (cPLA2) and PGF synthase (PGFS) was lower (P < 0.05) whereas, PGE synthase and peroxisome proliferator-activated receptors such as PPAR-γ and δ was increased (P < 0.05) in n-3 PUFA fed doe. In conclusion, dietary supplementation of FO decreased the endometrial production of PGF2α and PGE2 by downregulating the COX-2, cPLA2 and PGFS transcripts in the doe. The findings suggest that n-3 PUFA influence embryo survival by modulating the endometrial PG.