The effect of cadmium on the bovinein vitrooocyte maturation and early embryo development

Abstract

Common pollutants such as heavy metals and cadmium is among those with high environmental concerns. In vivo studies had shown that cadmium (Cd) causes oocyte degeneration and embryo mortality, and lowers pregnancy rates in mammals. However, there is limited information available about direct effects of Cd on oocyte maturation and/or embryo development. This study was aimed to investigate if Cd has any effect on the oocyte maturation and/or embryo development in vitro. Bovine COCs were collected from the slaughter house and cultured for 24 h in serum-free media only (Controls) or supplemented with 0.2, 2.0 and 20.0 μM CdCl2. At 24 h cumulus cell expansion was assessed in all COCs. COCs were either denuded and stained for determination of nuclear maturation or fertilized for assessment of subsequent embryo development. Cd at the lowest concentration (0.2 μM) did not affect any of the parameters studied. However, at higher concentrations (2.0 and 20.0 μM) it significantly (P < 0.05) reduced the percentage of fully-expanded COCs and significantly (P < 0.05) increased the percentage of partially and/or non-expanded COCs compared to controls and 0.2 μM. Cadmium at higher concentrations (2.0 and 20.0 μM) also significantly (P < 0.01) reduced the percentage of oocytes reaching metaphase II stage compared to controls and 0.2 μM. Post-fertilization cleavage rate in presumptive zygotes and blastocyst development significantly (P < 0.05) reduced 0.2, 2.0 and 20.0 μM CdCl2 compared to the controls (0.0 μM). In conclusion, these results suggest that Cd had direct detrimental effects on the bovine oocyte maturation and its developmental competence.

Disorders of the Reproductive Health of Cattle as a Response to Exposure to Toxic Metals

“…Higher concentrations significantly reduce the viability and maturation of oocytes, leading to their death. According to the in vitro research on bovine oocytes by Akar et al (2018) [19], a concentration of 2.0 and 20.0 µM CdCl2 after 24 h of incubation showed a negative effect on oocyte maturation, development, and morphological abnormities of oocytes, leading to their death. Moreover, higher amounts of cadmium (2.0 and 20.0 µM CdCl2) absorbed by bovine oocytes and blastocysts cause damage of the oocyte nuclei and the morphological defects of the blastocyst [19].…”

“…The main sources of cadmium in the environment are Ni-Cd batteries, mining and smelting, and forest fires [36]. Cadmium bioaccumulates mainly in the lungs, kidneys, liver, bones, testes, epididymis, follicular fluid, and it enters the body through the consumption of feed and water [6,7,19,35,37]. A typical blood concentration of cadmium in livestock animals should not exceed 1 ppm [48].…”

“…Toxic metals show an embryotoxic, a hepatoxic, a nephrotoxic, as well as a carcinogenic and mutagenic effect on living creatures [ 6 ]. They are non-biodegradable and widespread in the environment [ 6 , 19 ]. However, the most toxic to animals and humans are lead, cadmium, mercury, and arsenic [ 7 ].…”

“…Toxic metals, such as lead, arsenic, mercury, and cadmium, can affect animal fertility, for example, gametogenesis in cattle and in other ruminants [ 6 , 19 ]. Furthermore, there are also some elements that influence the biological functions of animals: chromium, copper, iron, selenium, nickel, zinc, manganese, molybdenum, and cobalt, among others ( Figure 2 ) [ 6 ].…”

Assessment of metals induced histopathological and gene expression changes in different organs of non-diabetic and diabetic rats

“…As, is known as carcinogenic chemical and responsible for toxicity in kidney, lung, skin, urinary bladder, liver and prostate 19 . The Cd toxicity results in physiological damage to transport proteins and mitochondria and causes apoptosis in different organs such as liver, kidney, skin, lungs and reproductive organs 20 . Overexposure to Mn has been reported to generate reactive oxygen species (ROS) and cause extensive neural, cardiovascular and hepatic damage 21 .…”