I have found many in literature data. Some authors describe increased levels of non-enzymatic antioxidant & enzymatic antioxidant (SOD, CAT, GSH, GST etc) under abiotic stress(Salt,heavy metal etc) for plants while others reported inverse correlation.
What are the factors influencing those results?
Do antioxidant enzymes increase or decrease under oxidative stress during time period like after 1 week level increased but 2nd week decrease 3rd week again activated ?
Is production of non-enzymatic antioxidant & enzymatic antioxidant are unpredictable?
If any literature supported above line please share link/paper.
This is a very interesting question and I am also fascinated to find out the exact answer. I have heard different interpretations of these types of results. One school propose that because of the increase in oxidants the AOX enzymes increase to try and combat the development of oxidative stress while some argue that the enzymes decrease because of depletion due to their actions of combating oxidative stress. or there decrease is due to the effect of the oxidants preventing production and thus disturbing the balance. I will watch this space for some more relevant discussion.
Perhaps it may also be dependent on the nature and concentration of toxicant that is administered/ exposed. In addition to the magnitude of tolerance/resistance of the exposed organism. It is well evident from the literature that the biochemical gestures in lower or higher organisms could vary against different toxicants in different patterns, besides, the mechanism through which the randomly generated ROS are countered under specified conditions still remains unknown. It is high time that we investigate the possible reasons behind these uneven responses and resolve the riddles of intercascadic biochemical changes.
The questions you're asking are very broad. The answer will vary depending on the source of oxidative stress, its intensity, its duration, the organisms and cell types that you're dealing with, etc.
I can say though that acute treatment of some human cells such as monocytes with a drug that causes oxidative stress will typically induce expression of antioxidant enzymes, at least in the short term.
Hmn! Quite interesting. It is well known that oxidative stress will definitely reduce the antioxidant status of enzymes in the biological system but if I would try and dig deep into some findings, I will definitely go beyond that fact. This is because there are some machineries that are responsible for coordinating the transcription of some genes that are responsible for upregulating some antioxidant enzymes and the components of these machineries respond to oxidative stress-related signals. So, oxidative stress could lower antioxidant enzyme status while at the same time set the platform for activating some transcription factors responsible for bringing those enzymes back to life. But the issue here is that oxidative stress cannot put itself on hold. A very good example is the high glucose concentration that will lead to oxidative stress in cells and later causes the upregulation of Nrf2 transcription factor. The activation of this transcription factor holds the strength to activate the transcription of antioxidant gene like those of the phase II reactions. But, to put oxidative stress on hold, it requires an external Nrf2 activator that will counteract the oxidative stress-related Nrf2 activation which is deliterous to the cells. So, it means we have two Nrf2 activators, 1. Oxidative stress 2. External compound or factor. I think for in vitro scenario, antioxidant enzyme activity could be downregulated but also depend on the condition of the in vitro environment. I hope this helps. Maybe you need to read more on Nrf2/Keap1/ARE pathway. It might give you a better elucidation.
First consider, what is the meaning of "increase in enzyme activity"? This may mean "increase in the number of enzyme molecules" in a given volume, or " if the number of enzyme molecules is fixed in a given volume, then alterations of active sites of the enzyme molecules such that they convert more substrates to product'. In in vitro scenario, NONE OF THE ABOVE TWO HAPPENS, so, in my opinion the antioxidative enzyme activities would decrease in in vitro conditions. However, in in vivo condtion both or either of the two might happen.
it depends on methods used by researcher, please examine antioxidant enzyme methods.
It also depends on the duration of exposure in in vivo condition. But in in vitro condition the activities would decrease as told by Dr. Hossain.
Well, depends on the level of the oxidative stress (OS). In general OS is adaptive reaction of the body to any alteration of environmental or internal conditions. The first reaction of the AOE to the OS is to increase the activity and/or expression. If OS accelerates, the activity of the AOE may decline due to oxidative damage of the proteins (antioxidant enzymes), or genes responsible for the AOE expression.
It depends on situation, factors such as oxidative stress(os) level, its duration....
so may be the production of antioxidants enzyme increase in response to oxidative stress or because of situation decrease(increase to combat the development of oxidative stress or decrease because of depletion due to their actions of combating oxidative stress), if your study is interventional, you can compare the level of antioxidant between two groups or in case- control study compare it between cases and controls.
Some antioxidants in some cases act as pro-oxidants and this could decrease the level of the antioxidants at that moment. Thank you.
in my opinion, we can not analyze the activity of antioxidant after treatment (chemical, physical, biological treatment) without analyze the change of the active compound or re profiling the active compound. because some treatment or let say chemical addition will change the form of active compund (in term of chemical structure), this change will give different effect to actioxidant activity, some of new chmeical structure of one sample maybe will increase the antioxidant acticity, and maybe the result is decrease for another sample. we can not generelize the effect of addition or treatment.
antioxidant enzymes increase or decrease under oxidative stress long time as the oxidative stress remains. I join this reference for more info
Kinin B1 receptor enhances the oxidative stress in a rat model of insulin resistance: outcome in hypertension, allodynia and metabolic complications.
Dias JP1, Talbot S, Sénécal J, Carayon P, Couture R. 2010
Best
antioxidant enzymes increase under oxidative stress as long as the oxidative stress remains. I join this reference for more info.
Kinin B1 receptor enhances the oxidative stress in a rat model of insulin resistance: outcome in hypertension, allodynia and metabolic complications.
Dias JP1, Talbot S, Sénécal J, Carayon P, Couture R. 2010
Best
Do antioxidant enzymes increase or decrease in vitro under oxidative stress? - ResearchGate. Available from: https://www.researchgate.net/post/Do_antioxidant_enzymes_increase_or_decrease_in_vitro_under_oxidative_stress [accessed Aug 15, 2016].
I agree with the answer given by Maria Traykova that activities of antioxidant enzymes increase in response to environmental stresses owing to increase in oxidative stress. But as the oxidative stress increases, their activity may decrease due to damage caused by oxidative stress to the proteins and damage to the genes responsible for expression of these antioxidant enzymes.
Many research points to a direct correlation between oxidative stress and antioxidant enzymes, and the latter are regulated by antioxidant genes.
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