2Department of Physiology and General Pathology, Faculty of Fundamental Medicine, Lomonosov Moscow State University, 119991 Moscow, Russia
3Pertsov White Sea Biological Station, Moscow State University, 186671 Loukhsky District, Republic of Karelia, Russia
* To whom correspondence should be addressed.
Received January 1, 2022; Revised January 24, 2022; Accepted January 24, 2022
Color vision sensitivity is crucial for fish adaptation during migration and reproduction. Prolactin and prolactin-like hormone are important regulators in both these processes. We hypothesized that prolactin influences the color vision sensitivity during freshwater migrations in fish. We studied the effects of prolactin and freshwater adaptation during the spawning period on the expression of opsin genes (SWS1, SWS2, RH2, LWS) in the retina of female and male three-spined sticklebacks Gasterosteus aculeatus L. Expression of the prolactin gene increased in the brain of females, but not males, while expression of the prolactin-like hormone decreased in the brain of both male and female sticklebacks during freshwater adaptation. Expression of the SWS2 gene decreased in the retina of females and males during freshwater adaptation and after prolactin administration. Expression of the SWS1 gene decreased in the retina of male sticklebacks after prolactin administration, but not during freshwater adaptation. Expression of the RH2 and LWS genes did not depend on prolactin administration in male and female sticklebacks. We conclude that expression of some opsin genes in the retina of sticklebacks is regulated by prolactin and depends on sex and freshwater adaptation. This expands our knowledge of the adaptive effects of prolactin on fish during freshwater migrations.
KEY WORDS: prolactin, opsins, three-spined stickleback Gasterosteus aculeatus L., freshwater adaptation, color vision adaptation, sex-dependent effects