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.