Medroxyprogesterone Acetate Drug Induced Reproductive Changes in Female Mosquito Fish Gambusia Affinis

Abstract

Medroxyprogesterone acetate (MPA) is an hormone analogue of progesterone that is usually used in combination with estrogen content in restarting the menstrual cycles that has been abruptly stopped, this will be done as a part of hormone displacement therapy. The presence of this compound have evidently been found in the aquatic ecosystems. The effect of this compound was found out on the freshwater mosquito fish viz Gambusia affinis. The commercially available pill containing MPA is Modus-10 which was used to test upon the fish. Fresh stock of the test fish were procured from the ponds available in Karnataka State Akkamahadevi Women University and as well as from the Fisheries Research and Information Centre, Bhutnal, Vijayapura. The fishes were reared in laboratory conditions for acclimatization before starting the experiment, the fishes were maintained in 3 groups of 6 individuals each (n=6), 3 males and 3 females. The fishes were maintained in static-renewal toxicity system. One group served as a control while other two groups were treated with two different doses of the drug 6mg and 12mg per aquarium per day. They were fed with commercial fish feed at 0.5gm per day. The female fishes were dissected on 29^th day and it was found that the drug treatment had affected their ovaries morphologically and physiologically. It was found out in the treated group of fishes that the eggs had reduced yolk granules, reduced number of eggs, larval mortality, over-ripen eggs, and the rate of fertilization was also affected. Further the histopathological studies of the treated fish ovaries revealed remarkable changes in the structure of the ova when compared with the structure of the ovary from the control group. The pre-vitellogenic follicles and vitellogenic oocytes were also malformed. The stress caused due to the drug exposure might be attributed to the changes in the ovaries. The ovaries from higher dosage exposure group(12mg) were contrarily found to be less affected when compared to lower dose, this can be related to the findings by Schreck et. al 2010, that the stressor molecules when present in higher concentration makes the fish to show coping type of responses so the histological details show less affect of the drug to the ovary but the ova which were found structurally appeared normal but no fertilized eggs were found, so the reproductive aspects are somehow affected. So the results found here substantiates the economic use of these pills and responsible disposure of the left outs so that the non-target animals aren’t affected by this.