Melatonin supplementation protects against the benzo(e)pyrene cytotoxicity and optic cup formation disruption in chicken embryos

Abstract

Benzo(e)pyrene is a cytotoxic chemical to the
 eyes, while neurohormone melatonin may exhibit protective effects on this
 cytotoxicity. In the current study, we have investigated the cytotoxic effects
 of benzo(e)pyrene on the chicken embryonic optic cups formation and whether
 melatonin supplementation protects chicken embryos against this xenobiotic
 toxicity. Fertilized chicken eggs were incubated for 48 h and then, they were
 divided into different groups. These groups included basal (without any
 treatment), control (distilled water), benzo(e)pyrene, melatonin and
 benzo(e)pyrene + melatonin groups, respectively. The 10 µl of distilled water
 or same volume of solution containing treatment compounds were injected into
 the air sac of the chicken egg. After an additional 18 h of incubation, the
 chicken embryos were excised and analyzed. The cytotoxicity was measured by a
 colorimetric whole chick embryo trypan blue assay. In embryos from basal,
 control and melatonin (0.01, 1 and 100 µM) groups, the frequency of the embryos
 with normal optic cups was 100% and had no increase in the embryonic cell death
 observed in post excision. In contrast, the frequency of normal optic cups in the
 benzo(e)pyrene (0.02 to 1200 µM) groups was significantly reduced (log IC50=
 -4.24 ± 0.02, R2= 0.98) with concentration-responsive manner. In
 addition, an increase in the embryonic cell death was also observed (log IC50 =
 -7.23 ± 0.28; R2 = 0.63). Melatonin treatment dose-responsively inhibited
 the benzo(e)pyrene-induced optic cups abnormality by 22.35 ± 4.06, 76.38 ± 3.30
 and 100 % at the concentrations of 0.01, 1 and 100 µM, respectively. This same
 phenomenon was also observed in benzo(e)pyrene-induced embryonic cell death,
 i.e., melatonin suppressed the embryonic cell death by 16.67 ± 4.17, 54.17 ±
 4.17 and 100 % with the abovementioned concentrations, respectively. Thus, melatonin
 supplementation injected into the chicken eggs protected against the
 benzo(e)pyrene embryotoxicity. Different pathways can be involved in melatonin’s
 protective effects.

Targeting Host Defense System and Rescuing Compromised Mitochondria to Increase Tolerance against Pathogens by Melatonin May Impact Outcome of Deadly Virus Infection Pertinent to COVID-19

“…Melatonin is a naturally occurring molecule assumed to be present in every species [ 19 ]. Due to its antioxidant, anti-inflammatory, as well as other properties [ 20 , 21 , 22 , 23 , 24 , 25 ], it has been speculated to be a promising molecule for treating COVID-19 patients [ 18 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ], and also other deadly viral infectious diseases [ 48 , 49 , 50 , 51 ]. A small scale clinical trial has also shown promising results [ 52 ].…”