%0 Journal Article %J Frontiers in Physiology %D 2022 %T Transient Receptor Potential-Vanilloid (TRPV1-TRPV4) Channels in the Atlantic Salmon, Salmo salar. A Focus on the Pineal Gland and Melatonin Production %A Nisembaum, Laura Gabriela %A Loentgen, Guillaume %A L'Honoré, Thibault %A Martin, Patrick %A Paulin, Charles-Hubert %A Fuentès, Michael %A Escoubeyrou, Karine %A Delgado, Maria Jesus %A Besseau, Laurence %A Falcón, Jack %K Atlantic salmon %K melatonin %K pineal organ %K Temperature %K transient receptor potential vanilloid (TRPV) %K TRPV1 %K TRPV4 %X Fish are ectotherm, which rely on the external temperature to regulate their internal body temperature, although some may perform partial endothermy. Together with photoperiod, temperature oscillations, contribute to synchronizing the daily and seasonal variations of fish metabolism, physiology and behavior. Recent studies are shedding light on the mechanisms of temperature sensing and behavioral thermoregulation in fish. In particular, the role of some members of the transient receptor potential channels (TRP) is being gradually unraveled. The present study in the migratory Atlantic salmon, Salmo salar, aims at identifying the tissue distribution and abundance in mRNA corresponding to the TRP of the vanilloid subfamilies, TRPV1 and TRPV4, and at characterizing their putative role in the control of the temperature-dependent modulation of melatonin production—the time-keeping hormone—by the pineal gland. In Salmo salar, TRPV1 and TRPV4 mRNA tissue distribution appeared ubiquitous; mRNA abundance varied as a function of the month investigated. In situ hybridization and immunohistochemistry indicated specific labeling located in the photoreceptor cells of the pineal gland and the retina. Additionally, TRPV analogs modulated the production of melatonin by isolated pineal glands in culture. The TRPV1 agonist induced an inhibitory response at high concentrations, while evoking a bell-shaped response (stimulatory at low, and inhibitory at high, concentrations) when added with an antagonist. The TRPV4 agonist was stimulatory at the highest concentration used. Altogether, the present results agree with the known widespread distribution and role of TRPV1 and TRPV4 channels, and with published data on trout (Oncorhynchus mykiss), leading to suggest these channels mediate the effects of temperature on S. salar pineal melatonin production. We discuss their involvement in controlling the timing of daily and seasonal events in this migratory species, in the context of an increasing warming of water temperatures. %B Frontiers in Physiology %V 22 %P 15 %8 01/2022 %G eng %U https://www.frontiersin.org/articles/10.3389/fphys.2021.784416/full?&utm_source=Email_to_authors_&utm_medium=Email&utm_content=T1_11.5e1_author&utm_campaign=Email_publication&field=&journalName=Frontiers_in_Physiology&id=784416 %N 784416 %9 original research %R 10.3389/fphys.2021.784416 %0 Journal Article %J Frontiers in Physiology %D 2021 %T Pituitary Hormones mRNA Abundance in the Mediterranean Sea Bass Dicentrarchus labrax: Seasonal Rhythms, Effects of Melatonin and Water Salinity %A Jack Falcon %E Maria-Jesus Herrero %E Laura-Gabriela Nisembaum %Y Esther Isorna %Y Elodie Peyric %Y Marilyn Beauchaud %Y Joel Attia %Y Denis Covès %Y Michael Fuentès %Y Maria-Jesus Delgado %Y Laurence Besseau %K annual variations %K hormones %K melatonin %K photoperiod %K pituitary %K salinity %K sea bass %X In fish, most hormonal productions of the pituitary gland display daily and/or seasonal
rhythmic patterns under control by upstream regulators, including internal biological
clocks. The pineal hormone melatonin, one main output of the clocks, acts at different
levels of the neuroendocrine axis. Melatonin rhythmic production is synchronized mainly
by photoperiod and temperature. Here we aimed at better understanding the role
melatonin plays in regulating the pituitary hormonal productions in a species of scientific
and economical interest, the euryhaline European sea bass Dicentrarchus labrax. We
investigated the seasonal variations in mRNA abundance of pituitary hormones in two
groups of fish raised one in sea water (SW fish), and one in brackish water (BW fish). The
mRNA abundance of three melatonin receptors was also studied in the SW fish. Finally,
we investigated the in vitro effects of melatonin or analogs on the mRNA abundance of
pituitary hormones at two times of the year and after adaptation to different salinities.
We found that (1) the reproductive hormones displayed similar mRNA seasonal profiles
regardless of the fish origin, while (2) the other hormones exhibited different patterns
in the SW vs. the BW fish. (3) The melatonin receptors mRNA abundance displayed
seasonal variations in the SW fish. (4) Melatonin affected mRNA abundance of most
of the pituitary hormones in vitro; (5) the responses to melatonin depended on its
concentration, the month investigated and the salinity at which the fish were previously
adapted. Our results suggest that the productions of the pituitary are a response to
multiple factors from internal and external origin including melatonin. The variety of the
responses described might reflect a high plasticity of the pituitary in a fish that faces
multiple external conditions along its life characterized by marked daily and seasonal
changes in photoperiod, temperature and salinity. %B Frontiers in Physiology %V 12 %P 774975 %8 12/15/2021 %G eng %U https://www.frontiersin.org/articles/10.3389/fphys.2021.774975/full?&utm_source=Email_to_authors_&utm_medium=Email&utm_content=T1_11.5e1_author&utm_campaign=Email_publication&field=&journalName=Frontiers_in_Physiology&id=774975 %9 Research article %! Melatonin and the Pituitary Hormones in the Sea Bass %R 10.3389/fphys.2021.774975 %0 Journal Article %J Journal of Comparative Physiology B %D 2020 %T Effects of a temperature rise on Atlantic salmon, Salmo salar, melatonin and thyroid hormones during smoltification %A Nisembaum, Laura Gabriela %A Martin, Patrick %A Fuentès, Michael %A Besseau, Laurence %A Magnanou, Elodie %A McCormick, Stephen D %A Jack Falcon %K Atlantic salmon %K melatonin %K smoltification %K Temperature %K thyroid hormones %X Smoltification prepares juvenile Atlantic salmon (Salmo salar) for downstream migration. Dramatic changes characterize this crucial event in the fish life cycle, including gills’ Na+/K+-ATPase activity (NKA) and plasma hormonal levels. The triggering of smoltification relies on photoperiod and is modulated by temperature. Both provide reliable information, to which fish adapted for thousands of years, that allows deciphering daily and calendar time. Here we studied the impact of different photoperiod (natural, sustained winter solstice) and temperature (natural, ~ +4°C) combinations, on gills’ NKA, plasma free triiodothyronine (T3), thyroxine (T4) and melatonin (MEL; the time-keeping hormone), throughout smoltification. We also studied the impact of temperature history on pineal gland MEL production in vitro. The spring increase in gills’ NKA was less pronounced in smolts kept under sustained winter photoperiod and/or elevated temperature. Plasma thyroid hormones levels displayed day-night variations, which were affected by elevated temperature, either independently from photoperiod (decrease in T3 levels) or under natural photoperiod exclusively (increase in T4 nocturnal levels). Nocturnal MEL secretion was potentiated by the elevated temperature, which also altered MEL profile under sustained winter photoperiod. Temperature also affected pineal MEL production in vitro, a response that depended on previous environmental acclimation of the organ. The results support the view that the salmon pineal is a photoperiod and temperature sensor, highlight the complexity of the interaction of these environmental factors on S. salar endocrine system, and suggest that climate change might compromise salmon’s time “deciphering” and processes such as smoltification, downstream migration and seawater residence. %B Journal of Comparative Physiology B %V 190 %P 731-748 %8 09/2020 %G eng %U https://link.springer.com/article/10.1007/s00360-020-01304-2 %9 ACL %R 10.1007/s00360-020-01304-2 %0 Journal Article %J J Comp Physiol B %D 2020 %T Effects of a temperature rise on melatonin and thyroid hormones during smoltification of Atlantic salmon, Salmo salar %A Nisembaum, Laura Gabriela %A Martin, Patrick %A Fuentès, M %A Besseau, Laurence %A Magnanou, Elodie %A McCormick, Stephen %A Falcón, Jack %K Atlantic salmon %K melatonin %K Temperature %K thyroid hormones %X Smoltification prepares juvenile Atlantic salmon (Salmo salar) for downstream migration. Dramatic changes characterize this crucial event in the salmon’s life cycle, including increased gill Na+/K+-ATPase activity (NKA) and plasma hormone levels. The triggering of smoltification relies on photoperiod and is modulated by temperature. Both provide reliable information, to which fish have adapted for thousands of years, that allows deciphering daily and calendar time. Here we studied the impact of different photoperiod (natural, sustained winter solstice) and temperature (natural, ~ + 4° C) combinations, on gill NKA, plasma free triiodothyronine (T3) and thyroxine (T4), and melatonin (MEL; the time-keeping hormone), throughout smoltification. We also studied the impact of temperature history on pineal gland MEL production in vitro. The spring increase in gill NKA was less pronounced in smolts kept under sustained winter photoperiod and/or elevated temperature. Plasma thyroid hormone levels displayed day–night variations, which were affected by elevated temperature, either independently from photoperiod (decrease in T3 levels) or under natural photoperiod exclusively (increase in T4 nocturnal levels). Nocturnal MEL secretion was potentiated by the elevated temperature, which also altered the MEL profile under sustained winter photoperiod. Temperature also affected pineal MEL production in vitro, a response that depended on previous environmental acclimation of the organ. The results support the view that the salmon pineal is a photoperiod and temperature sensor, highlight the complexity of the interaction of these environmental factors on the endocrine system of S. salar, and indicate that climate change might compromise salmon’s time “deciphering” during smoltification, downstream migration and seawater residence. %B J Comp Physiol B %8 03 September 202 %G eng %U https://link.springer.com/article/10.1007%2Fs00360-020-01304-2 %9 Journal Article %R 10.1007/s00360-020-01304-2