Effects of waterborne luteinizing hormone and follicle-stimulating hormone on reproduction of the rotifer Brachionus calyciflorus (Monogononta: Brachionidae)

Abstract

This study used freshwater rotifers to evaluate the effects of two endocrine disrupting compounds (EDCs), luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which can be considered emergent contaminants in urban and rural wastewater and are of ecotoxicological importance. LH stimulates the synthesis of testosterone, whereas FSH promotes the maturation of follicles and sperm in vertebrates and invertebrates. However, in rotifers, there are no reports of the effects of chronic exposure to these hormones when added to reconstituted culture medium, as a way to study potential adverse effects that might occur in the environment. Therefore, we studied the reproductive effects of the rotifer Brachionus calyciflorus Pallas 1766 using a 4-day reproductive assay. Our results indicate that LH has a significant effect in increasing the production of females, males, and cysts, while FSH had no significant effect compared to control treatment. Additionally, our results indicate that LH exposure resulted in 0.33% of organisms being deformed, whereas FSH exposure resulted in 1.09% of organisms being deformed. Deformations included: (a) abnormal growth of lorica, (b) joined foot-head, (c) deformed anterior spine, and (d) deformed parthenogenetic eggs. The organisms with LH-induced deformations did not reproduce and only lived 48 h after 4 days of exposure, while those with FSH-induced deformities survived 15 days and produced 105 cysts with a hatching percentage of 58.10%. Our goal was to contribute to the knowledge of endocrine systems and endocrine hormones of rotifers, to explain the potential mechanism of endocrine disruption that results in adverse effects in freshwater rotifers.