Anxiety‐Related Behavior and Biogenic Amine Pathways in the Rat following Bilateral Vestibular Lesions

Abstract

Many clinical studies have reported that patients with vestibular disorders have a high rate of anxiety disorders and depression. By contrast, there have been few studies of affective behavior in animals following vestibular lesions. Recent studies using the vestibular impaired ci2/ci2 mutant rat strain have shown that rather than preferring the closed arm of the elevated plus maze, as rats would normally, they make more open-arm entries and spend more time on the open arms compared to wild-type controls. In the open-field maze, rather than preferring to explore the outer zone near the walls ("thigmotaxis"), ci2/ci2 rats prefer the inner region of the maze. In rats with bilateral vestibular deafferentation (BVD), similar results were obtained. Compared to sham controls, at 3 and 5 months post-op, BVD rats spent more time on the open arms of the elevated plus maze, more time in the inner zone of the open-field maze, and failed to learn inhibitory avoidance in the elevated T maze. They did not display increased hyponeophagia; however, they did exhibit a decrease in social interaction. Blood corticosterone levels were not significantly different from sham controls. At 6 months post-op, BVD rats demonstrated circumscribed changes in the expression of tyrosine hydroxylase, the serotonin transporter, and tryptophan hydroxylase, in various regions of the medial temporal and frontal lobes, suggesting changes in biogenic amine pathways.

Mice with conditional deletion of Cx26 exhibit no vestibular phenotype despite secondary loss of Cx30 in the vestibular end organs

“…There is ample direct evidence of neuronal connections between the vestibular nucleus of the brainstem and centers regulating physiological and emotional states (Eiken et al, 2005; Horii et al, 1995; Nobel et al, 2010) as well as evidence that mutations affecting the vestibular organs can influence anxiety related behavioral patterns as well as locomotion (Darlington et al, 2009; Khan et al, 2004; Shefer et al, 2010). In addition, vestibular stimuli similar to those that induce motion sickness in humans also can provoke physiological shifts such as lowering core body temperature in humans and other mammals (Cheung et al, 2011; Holmes et al, 2002; Murakami et al, 2002; Nobel et al, 2012).…”

Vertigoheel improves central vestibular compensation after unilateral peripheral vestibulopathy in rats

“…Patients who suffer from a vestibular deficiency or dysfunction present a vestibular syndrome which is associated with anxiety symptoms (50,51). These anxiety symptoms indicate that vestibular function and emotional processes interact together (23). Anxiety-like behavior in rodents can be explored through different behavioral tests, such as the elevated plus maze (52), the black and white box test (22), and the openfield test (53).…”

“…First, patients who suffer from a vestibular deficiency or dysfunction present a vestibular syndrome, which is also associated with anxiety symptoms. These anxiety symptoms indicate that vestibular function and emotional processes interact together (23). Second, to learn more about the mode of action of Vertigoheel's effect on postural control.…”