Sustained hyperarousal induced by acute stress in tryptophan-hydroxylase-2 genetic deficient male mice

doi:10.3724/SP.J.1041.2022.00604

Abstract

Abstract:

Severe stress stimulation will cause persistent hyperarousal state, which is the core symptom of various stress disorders and promotes the occurrence and development of other symptoms. This study focused on the role of 5-hydroxytryptamine in the occurrence and development of stress-induced hyperarousal. By measuring the auditory startle reflex level to reflect the state of hyperarousal, we investigated the changes of hyperarousal in tryptophan hydroxylase-2 gene deficient mice before and after predator exposure or electric footshock stress. Studies have found that male genetically deficient mice showed hyperarousal performance lasting for more than one week after stress, while wild-type mice showed a hyperarousal state that recovered quickly. The results suggest that the decrease of serotonin caused by gene deficiency may be a susceptible factor of persistent hyperarousal induced by severe stress.

Key words: hyperarousal, 5-hydroxytryptamine, tryptophan-hydroxylase-2, auditory startle reflex

ZHOU Ping, XIAO Hua, LI Yonghui, DONG Xinwen. (2022). Sustained hyperarousal induced by acute stress in tryptophan-hydroxylase-2 genetic deficient male mice. Acta Psychologica Sinica, 54(6), 604-612.

Figures/Tables 3

Figure 1. Effects of sex and genotype on the amplitude of auditory startle reflex in mice.
Note. The error bar is standard error of mean (SEM). Cases in each group: male wild, n = 26; Male Tph2 +/-, n = 37; Female wild type, n = 31; Female Tph2 +/-, n = 29. The baseline value of startle reflex in male wild-type mice was significantly higher than that in female mice, *** p < 0.001, and there was no difference in baseline value of startle reflex between mice of the same sex and different genotypes.

Figure 2. Changes of auditory startle reflex amplitude in male mice before and after stress.
Note. The error bar is standard error of mean (SEM). Cases in each group: wild type control group, n=8, predator group, n=9, shock group, n=9; Tph2 +/- control group, n = 13, predator group, n = 10, shock group, n = 14. The * mark in the figure indicates the difference of startle reflex amplitude among male mice of different genotypes 10 days after electric shock stress, * p < 0.05.

Figure 3. Change of amplitude of auditory startle reflex in female mice before and after stress.
Note. The error bar is standard error of mean (SEM). Cases in each group: wild type control group, n = 12, predator group, n = 8, shock group, n = 11; Tph2 +/- Female control group, n = 12, predator group, n = 6, shock group, n = 11. The * mark in the figure indicates the difference of startle reflex amplitude among female mice of different genotypes 10 days after predator exposure stress, * p < 0.05.

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