Kiss1 kisspeptin of bony fish and mammalian kisspeptin analogs enhance the communicative behavior of <i>Danio rerio</i> induced by social isolation

Abstract

BACKGROUND: Rodents are often used as a social isolation model. This study investigated the effects of social isolation on Danio rerio. These animals form groups and social hierarchies and exhibit complex social interactions similar to rodents. The expression of some brain genes of fish reared in isolation was found to be different from individuals reared in a group. AIM: This study aimed to investigate the effect of kisspeptins on the social behavior of Danio rerio in social isolation. MATERIALS AND METHODS: Fish were placed in 200-mL measuring cups for 48 h. After the social isolation period, bony fish kisspeptins and mammalian kisspeptin analogs were administered, and their effects were tested. The animal was placed in 1-L individual tanks for 15 min and then in the tank with a glass partition, behind which are a group of congeners. Fish were allowed to approach or swim away from the partition. Two patterns were used to assess behavior: latency time and number of swims to the partition. RESULTS: Compared with the control group with fish kept in social isolation, reliable differences were observed: The number of swims to the partition after isolation was 1.3 times higher than that in the control group (p 0.05). After the administration of bony fish kisspeptins Kiss1 and Kiss2, no significant changes in the number of swims to the partition were observed. Moreover, after the administration of KS6 and KS10, the number of swims to the aquarium partition increased 1.6 times (p 0.01) and 1.8 times (p 0.001), respectively. After the administration of the comparison drug oxytocin, the number of swims to the aquarium partition increased 1.6 times (p 0.01) compared with that in the untreated isolated group. The latency time of swimming to the partition increased 2.4 times in the untreated isolated group compared with the control group (p 0.001). Latency time decreased 2.3 times in the group administered with oxytocin compared with the untreated isolated group (p 0.001). In the group administered with Kiss1, the latency time decreased 2 times (p 0.001) compared with that in the untreated isolated group. The latency time decreased 5 times (p 0.001) after KS10 administration and 3.4 times (p 0.001) after KS6 administration compared with that in the untreated isolated group. CONCLUSIONS: Thus, social isolation in Danio rerio reduces communicative behavior. Analogs of mammalian kisspeptin, such as Kiss1, of bony fish and oxytocin normalize the communicative behavior of fish after a period of social isolation to the level of the control group.