Page 82 - 《水产学报》2025年第6期

张潭，等 水产学报, 2025, 49(6): 069106

Effects of high-temperature stress on the histopathology of gills and
liver tissues and serum biochemical indicators of Hucho taimen

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ZHANG Tan , TONG Guangxiang , XU Huan , YAN Ting ,
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WEI Mingliang , ZHANG Tingting , KUANG Youyi 2*
1. College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China;
2. Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China
Abstract: Temperature fluctuations caused by climate change and global warming pose significant threats to various species.
Understanding the mechanisms of fish tolerance to high temperatures can help develop effective strategies to cope with climate
changes in aquaculture. Hucho taimen is an important economic cold-water salmonid. This study designed a temperature accli-
mation protocol that included gradual warming from an optimal 18 ℃ to 26 ℃, maintaining 26 ℃ for 7 days, and then redu-
cing the temperature back to 18 ℃. The impact of high temperature on taimen was compared and analyzed through respiratory
rate, histopathology, and serum biochemical indicators. The results demonstrated that during the gradual temperature increase
from the optimal 18 ℃ to 26 ℃, the respiratory rate of taimen accelerated with rising temperature. Histopathological changes in
gills and liver tissues at the cellular level progressively worsened, including hypertrophy and rupture of gill epithelial cells, as
well as hepatocellular hypertrophy, vacuolization, and necrosis. At 26 ℃, the pathological grad reached a severe level (with
lesions comprising over 61% of the tissue). Serum enzyme activities of aspartate aminotransferase (AST), alanine aminotrans-
ferase (ALT), and lactate dehydrogenase (LDH) activities sharply increased with the rising temperature. Alkaline phosphatase
(ALP) activity remained unchanged at 22 ℃ but significantly decreased at 26 ℃. The total cholesterol (TC) content gradually
decreased, while the total protein (TP) content initially decreased and then recovered. During the 7-day period of high temperature at
26 ℃, the respiratory rate of taimen remained consistently higher than that of control group. Histopathological deterioration of
in the gills and liver tissues further intensified, including epithelial necrosis, vascular occlusion, and secondary lamellar fusion
in the gills, as well as hepatic congestion, lipid infiltration, and inflammatory cell infiltration. The histopathological grad peaked
at 105 h, followed by a gradual decrease in lesions. Serum enzyme activities of AST, ALT, and LDH activities initially
decreased sharply and then increased, while ALP activity at first increased and then normalized. TC content slowly recovered,
and TP content initially decreased and then returned to normal. After returning to 18 ℃ from 26 ℃, the respiratory rate returned
to normal levels, gill tissues recovered completely, and liver tissues had partial recovery, though there was moderate lipid infilt-
ration and inflammatory cell infiltration (lesions comprising 31%-60% of the tissue). Serum enzyme activities of AST, ALT,
and LDH activities decreased but remained significantly higher than that of the control group, while ALP activity showed a
sharp increase. TC and TP contents restored to normal levels. The study found that the respiratory rate of taimen increased with
rising temperatures, and high-temperature stress caused the respiratory rate to remain elevated above normal levels. This
demonstrated an increased oxygen demand and metabolic rate under high-temperature stress. High-temperature stress induced
various types and degrees of lesions in the gill and liver tissues of taimen. After the temperature returned to normal, the gill tis-
sues recovered, while the liver tissues showed partial recovery but remained in a significantly pathological state. High-temperat-
ure stress affected the liver functions related to metabolism, synthesis, and storage, with a more significant impact on metabolic
capacity. The combined analysis of respiratory rate, pathology, and biochemical indicators suggests that taimen has some adapt-
ive capacity to high-temperature stress. These findings of this research provide a theoretical foundation for the physiological
regulatory mechanisms of temperature tolerance in taimen, as well as for the efficient aquaculture and selection of high-temper-
ature resistant strains.
Key words: Hucho taimen; high-temperature stress; respiratory rate; histopathology; serum biochemical indicators
Corresponding author: KUANG Youyi. E-mail: kuangyouyi@hrfri.ac.cn
Funding projects: National Key R & D Program of China (2022YFD2400101); Central Public-interest Scientific Institution
Basal Research Fund, HRFRI (2023TD22)

https://www.china-fishery.cn 中国水产学会主办 sponsored by China Society of Fisheries
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