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. 2023 Jan 30;29(1):72–84. doi: 10.5056/jnm22009

Figure 3.

Figure 3

Chronic stress induces changes in enteric neurotransmitters and down regulated the expression of tyrosine hydroxylase (Th) mRNA in proximal colon. Levels of noradrenaline (NA), dopamine (DA), serotonin (5-HT), and metabolites from dopamine and 5-HT were measured by high-performance liquid chromatography (HPLC) in ileum and colon in control and stress mice (n = 7-8/group). (A) Levels of NA, DAc, and 5-HT were significantly greater than those in control mice only in proximal colon of stressed mice. No HVA levels were detected in proximal colon of stressed mice. The total levels of Dopamine plus its metabolites (homovanillic acid [HVA] and 3,4-dihydroxyphenylacetic acid [DOPAC]) were significantly lower in distal colon of stressed mice than control. Total levels of 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) were significantly greater in proximal colon of stressed mice than controls. Quantitative real-time polymerase chain reaction was used to quantify to measure transcripts encoding Th in small intestine and colon of control and stressed mice (n = 10/ group). (B) In proximal colon transcript levels of Th negatively correlated with the concentration of NA and DA. Data represent mean ± SEM; *P < 0.05, **P < 0.01, ***P < 0.001 by t test (A, B) and Pearson analysis (B).