Abstract | Jedan od glavnih čimbenika loše kvalitete sjemena, a time i reproduktivne funkcije muških
životinja je upravo oksidacijski stres. Ovo se stanje razvija bilo da se radi o povećanom
stvaranju kisikovih i dušikovih reaktivnih spojeva (ROS/RNS) i/ili smanjenoj mogućnosti
antioksidativne obrane zbog smanjene sinteze ili smanjenog unosa antioksidativnih spojeva
kao što su vitamin E, A, C, karotenoidi i selen. Membrana spermija sisavaca bogata je
višestrukonezasićenim masnim kiselinama koje su osjetljive na peroksidaciju uzrokovanu
reaktivnim kisikovim spojevima. Zaštita spermija od oksidacijskog stresa od najveće je
važnosti. Spermiji i sjemena plazma sadrže enzime superoksid dismutazu, glutaton
peroksidazu, katalazu, paraoksonazu 1, glutation, tioredoksin, albumine i vitamine E i C.
Sjemena plazma ima veću koncentraciju antioksidansa od drugih bioloških tekućina te
nadoknađuje manju razinu ovih molekula prisutnih u spermijima.
Glavni izvor reaktivnih kisikovih spojeva su nezreli i mrtvi spermiji kao i leukociti koji
kontaminiraju sjeme. |
Abstract (english) | One of the most important factors contributing to poor quality semen and thus reproductive
functions of male animals has been reported to be oxidative stress. This condition develops
due to some or all of these factors: a) increased production of oxygen derived oxidants
commonly known as ROS; b) reduced antioxidant defense because of the reduced synthesis of
antioxidant molecules or c) a decreased intake of natural antioxidants such as vitamin E, A, C,
carotenoids and selenium. Mammalian spermatozoa membranes are rich in polyunsaturated
fatty acids (PUFA) and are sensitive to oxygen-induced damage mediated by lipid
peroxidation.
In order to maintain vital reproductive ability, a protective mechanism against oxidative stress
has great importance. To protect spermatozoa from oxidative stress, both spermatozoa and
seminal plasma contain antioxidants superoxide dismutase, glutathione peroxidases, catalase,
paraoxonase 1, glutathione, α-tocopherol, ascorbic acid, glutathione, thoredoxine and
albumin. Seminal plasma has a higher concentration of antioxidants than any other biological
fluid, including blood serum, which compensates for the low antioxidative capacity of
spermatozoa themselves.
The main source of ROS in immature forms of spermatozoa is considered to be proximal or
distal protoplasmic droplet, located below the head or on the tail in some of spermatozoa.
Such forms of immature sperms are not enduring and are infertile. In bovine and ram semen,
ROS are generated primarily by dead spermatozoa. Contaminating leukocytes in the ejaculate
are an important source of ROS in human and stallion semen. |