Quantitative Assessment of Anti-Gravity Reflexes to Evaluate Vestibular Dysfunction in Rats
AbstractThe tail-lift reflex and the air-righting reflex are anti-gravity
reflexes in rats that depend on vestibular function. To obtain objective and
quantitative measures of performance, we recorded these reflexes with slow-motion
video in two experiments. In the first experiment, vestibular dysfunction was
elicited by acute exposure to 0 (control), 400, 600, or 1000 mg/kg of
3,3′-iminodipropionitrile (IDPN), which causes dose-dependent hair cell
degeneration. In the second, rats were exposed to sub-chronic IDPN in the drinking
water for 0 (control), 4, or 8 weeks; this causes reversible or irreversible
loss of vestibular function de pending on exposure time. In the tail-lift test, we
obtained the minimum angle defined during the lift and descent maneuver by the nose,
the back of the neck, and the base of the tail. In the air-righting test, we
obtained the time to right the head. We also obtained vestibular dys function ratings
(VDRs) using a previously validated behavioral test battery. Each measure, VDR,
tail-lift angle, and air-righting time demonstrated dose-dependent loss of
vestibular function after acute IDPN and time-dependent loss of vestibular function
after sub-chronic ID PN. All measures showed high correlations between each other,
and maximal correlation coefficients were found between VDRs and tail-lift angles.
In scanning electron microscopy evaluation of the vestibular sensory epithelia, the
utricle ...
Source: JARO - Journal of the Association for Research in Otolaryngology - Category: ENT & OMF Source Type: research