Comparison of anxiolytic effects of mammalian and bony fish kisspeptins in <dfn>Danio rerio</dfn>

Abstract

In our previous work, we suggested that analogs of mammalian kisspeptin Kiss1 reduce anxiety and phobic reactions novel in Danio rerio. The most effective dose for the action of the studied analogs of kisspeptin corresponded to 0.1 mg per 1000 mL of water. In this study, other analogs of mammalian Kiss1 at a dose of 0.1 mg per 1000 mL of water also reduced the anxious behavior of Danio fish. The effect of Kiss1 and Kiss2 kisspeptins on the behavior of Danio rerio was also evaluated. In the novel test, the number of freezing decreased by two times with the introduction of kisspeptin 10 and by three times after the introduction of the kisspeptin analog. An analog of mammalian kisspeptin reduced the freezing time by two times. The length of the trajectory decreased by two times under the influence of the mammalian Kiss1 kisspeptin analog. With the action of kisspeptin 10, the number of transitions to the upper part of the tank increased by two times. After the introduction of the kisspeptin analog, the number of transitions to the upper part of the aquarium increased by three times. In the predator test, the number and time of freezing decreased by 1.5 times with the action of mammalian kisspeptins. The length of the trajectory after the introduction of kisspeptin bony fish and kisspeptin 10 mammals increased. The length of the trajectory after the introduction of Kiss1 increased by 1.5 times. The length of the trajectory after the introduction of Kiss2 increased by three times. After the introduction of kisspeptin 10, the trajectory increased by two times, and the time spent in the lower part of the tank decreased by two times. Kisspeptins of bony fish also reduced the anxiety and phobic reactions in fish, but to a lesser extent. Thus, kisspeptin 10 and an analog of mammalian kisspeptin in response to the presentation of a predator had more significant effects on anxiety in Danio rerio compared with the action of kisspeptin bony fish Kiss1 and Kiss2. Thus, bony fish kisspeptins and mammalian kisspeptins can reduce anxiety and phobic reactions in Danio rerio; however, mammalian kisspeptins are the most effective. Bony fish kisspeptin Kiss1 has an anxiolytic effect in contrast to Kiss2, which suggests that it affects fear reduction, and Kiss2 appears to be responsible for social and sexual behavior. The results support the hypothesis that kisspeptins may be involved in the regulation of anxiety and phobic states, apparently to maintain the emotional aspects of reproductive behavior, such as sexual motivation and arousal.