Fish physiology and biochemistryNov 14, 2015

Gut melatonin changes after infection in Catla catla fish

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Apr 3, 2026

Abstract

Gut melatonin levels in carp (Catla catla) increased significantly during Aeromonas hydrophila infection over 3 to 6 days.

Microscopic examination revealed degenerative changes in the gut lining of infected fish.
The activity of digestive enzymes decreased in response to infection.
Melatonin levels and the activity of antioxidative enzymes increased progressively with infection duration.
A positive correlation was observed between gut melatonin concentrations and antioxidative enzyme activity.
A negative correlation was found between melatonin levels and digestive enzyme activity.
Changes in gut and serum melatonin levels suggest a potential role of the gut in regulating circulating melatonin.

Simplified

The purpose of present study was to demonstrate the response of gut melatoninergic system to Aeromonas hydrophila infection for 3 or 6 days and search for its correlation with the activity of different antioxidative and digestive enzymes to focus their interplay under pathophysiological conditions in carp (Catla catla). Microscopic study of gut in infected fish revealed degenerative changes in the tunica mucosa and lamina propria layers with sloughed off epithelial cells in the lumen. The activity of each digestive enzyme was reduced, but the levels of melatonin, arylalkylamine-N-acetyl transferase protein, the key regulator of melatonin biosynthesis, and different enzymatic antioxidants in gut were gradually and significantly increased with the progress of infection. Gut melatonin concentrations in A. hydrophila challenged carp by showing a positive correlation with the activity of each antioxidative enzyme, and a negative correlation with different digestive enzymes argued in favor of their functional relation, at least, during pathological stress. Moreover, parallel changes in the gut and serum melatonin titers indicated possible contribution of gut to circulating melatonin. Collectively, present carp study provided the first data to suggest that endogenous gut melatonin may be implicated to the mechanism of response to microbial infections in any fish species.

Full Text

Full text is available at the source.

View Full Text ↗

Gut melatonin changes after infection in Catla catla fish

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief