Short-term ingestion of sublethal microcystin levels disrupts stress response in male mice

Cyanobacterial harmful algal blooms (cHABs) produce various cyanotoxins, primarily microcystin leucine arginine (MC-LR). Studies demonstrated that intraperitoneal delivery of high-dose MC-LR affects the rat stress response, which is regulated by the hypothalamus-pituitary-adrenal (HPA) axis. In gene...

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Main Authors: Salan Ghaju, Evance Pakuwal, Rafaela S. C. Takeshita, Xiaozhen Mou, Wilson C. J. Chung
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-05-01
Series:Frontiers in Endocrinology
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Online Access:https://www.frontiersin.org/articles/10.3389/fendo.2025.1568923/full
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author Salan Ghaju
Evance Pakuwal
Rafaela S. C. Takeshita
Rafaela S. C. Takeshita
Xiaozhen Mou
Xiaozhen Mou
Wilson C. J. Chung
Wilson C. J. Chung
author_facet Salan Ghaju
Evance Pakuwal
Rafaela S. C. Takeshita
Rafaela S. C. Takeshita
Xiaozhen Mou
Xiaozhen Mou
Wilson C. J. Chung
Wilson C. J. Chung
author_sort Salan Ghaju
collection DOAJ
description Cyanobacterial harmful algal blooms (cHABs) produce various cyanotoxins, primarily microcystin leucine arginine (MC-LR). Studies demonstrated that intraperitoneal delivery of high-dose MC-LR affects the rat stress response, which is regulated by the hypothalamus-pituitary-adrenal (HPA) axis. In general, during stress parvocellular neurons in the hypothalamic paraventricular nucleus (PVN) secrete corticotropin-releasing hormone (CRH), triggering adrenocorticotropic hormone (ACTH) release from the anterior pituitary, which leads to increased cortisol in humans and corticosterone in rats and mice. Here, we tested the hypothesis that short-term sublethal ingestion of MC-LR activates the peripheral and central components of the HPA axis. First, we found that young adult male mice gavaged with MC-LR (50 μg/kg bw, p.o.) every 2 days for 21 days had elevated plasma corticosterone levels when compared to H2O (vehicle) mice. Ingestion of contaminated fresh water is a likely natural route of MC-LR exposure for animals, including humans. Second, Crh and arginine vasopressin (Avp) mRNA expressions were elevated in the hypothalamus of MC-LR-dosed mice. Third, ΔFOSB (i.e., long-term cell activity marker) immunofluorescence in the PVN and hippocampal dentate gyrus (DG) of MC-LR mice was significantly elevated compared to vehicle mice, but not in cornu ammonis (CA) 1, 2 and 3. In contrast, MC-LR mice had reduced hypothalamic glucocorticoid receptor (Gr) mRNA expression. Fourth, no significant changes were found in the mRNA expression of the inflammatory markers: tumor necrosis factor α (Tnf-α) and interleukin-1β (IL-1β) in the hypothalamus, liver, and spleen and C-reactive protein (Crp) in the liver and spleen. These data indicate that short-term ingestion of sublethal levels of MC-LR resulted in increased peripheral and central HPA axis activity.
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spelling doaj-art-8bc86356d0684e8b96ad4c8221df5bf42025-08-20T01:57:15ZengFrontiers Media S.A.Frontiers in Endocrinology1664-23922025-05-011610.3389/fendo.2025.15689231568923Short-term ingestion of sublethal microcystin levels disrupts stress response in male miceSalan Ghaju0Evance Pakuwal1Rafaela S. C. Takeshita2Rafaela S. C. Takeshita3Xiaozhen Mou4Xiaozhen Mou5Wilson C. J. Chung6Wilson C. J. Chung7School of Biomedical Science, Kent State University, Kent, OH, United StatesDepartment of Medical Sciences, University of Adelaide, Adelaide, SA, AustraliaSchool of Biomedical Science, Kent State University, Kent, OH, United StatesDepartment of Anthropology, Kent State University, Kent, OH, United StatesSchool of Biomedical Science, Kent State University, Kent, OH, United StatesDepartment of Biological Sciences, Kent State University, Kent, OH, United StatesSchool of Biomedical Science, Kent State University, Kent, OH, United StatesDepartment of Biological Sciences, Kent State University, Kent, OH, United StatesCyanobacterial harmful algal blooms (cHABs) produce various cyanotoxins, primarily microcystin leucine arginine (MC-LR). Studies demonstrated that intraperitoneal delivery of high-dose MC-LR affects the rat stress response, which is regulated by the hypothalamus-pituitary-adrenal (HPA) axis. In general, during stress parvocellular neurons in the hypothalamic paraventricular nucleus (PVN) secrete corticotropin-releasing hormone (CRH), triggering adrenocorticotropic hormone (ACTH) release from the anterior pituitary, which leads to increased cortisol in humans and corticosterone in rats and mice. Here, we tested the hypothesis that short-term sublethal ingestion of MC-LR activates the peripheral and central components of the HPA axis. First, we found that young adult male mice gavaged with MC-LR (50 μg/kg bw, p.o.) every 2 days for 21 days had elevated plasma corticosterone levels when compared to H2O (vehicle) mice. Ingestion of contaminated fresh water is a likely natural route of MC-LR exposure for animals, including humans. Second, Crh and arginine vasopressin (Avp) mRNA expressions were elevated in the hypothalamus of MC-LR-dosed mice. Third, ΔFOSB (i.e., long-term cell activity marker) immunofluorescence in the PVN and hippocampal dentate gyrus (DG) of MC-LR mice was significantly elevated compared to vehicle mice, but not in cornu ammonis (CA) 1, 2 and 3. In contrast, MC-LR mice had reduced hypothalamic glucocorticoid receptor (Gr) mRNA expression. Fourth, no significant changes were found in the mRNA expression of the inflammatory markers: tumor necrosis factor α (Tnf-α) and interleukin-1β (IL-1β) in the hypothalamus, liver, and spleen and C-reactive protein (Crp) in the liver and spleen. These data indicate that short-term ingestion of sublethal levels of MC-LR resulted in increased peripheral and central HPA axis activity.https://www.frontiersin.org/articles/10.3389/fendo.2025.1568923/fullcyanobacterial harmful algal bloommicrocystinbrainstresshypothalamusparaventricular nucleus
spellingShingle Salan Ghaju
Evance Pakuwal
Rafaela S. C. Takeshita
Rafaela S. C. Takeshita
Xiaozhen Mou
Xiaozhen Mou
Wilson C. J. Chung
Wilson C. J. Chung
Short-term ingestion of sublethal microcystin levels disrupts stress response in male mice
Frontiers in Endocrinology
cyanobacterial harmful algal bloom
microcystin
brain
stress
hypothalamus
paraventricular nucleus
title Short-term ingestion of sublethal microcystin levels disrupts stress response in male mice
title_full Short-term ingestion of sublethal microcystin levels disrupts stress response in male mice
title_fullStr Short-term ingestion of sublethal microcystin levels disrupts stress response in male mice
title_full_unstemmed Short-term ingestion of sublethal microcystin levels disrupts stress response in male mice
title_short Short-term ingestion of sublethal microcystin levels disrupts stress response in male mice
title_sort short term ingestion of sublethal microcystin levels disrupts stress response in male mice
topic cyanobacterial harmful algal bloom
microcystin
brain
stress
hypothalamus
paraventricular nucleus
url https://www.frontiersin.org/articles/10.3389/fendo.2025.1568923/full
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