Vestibular-induced behaviour of rats born and raised in hypergravity.
One group of rats were bred and kept under hypergravity (HG) conditions (2.5 g) in a centrifuge. Another group were bred and kept under normal gravity conditions (1 g). Rats from both groups were dropped from a supine position into a water basin under infrared illumination leaving only gravity (1 g for both groups) for orientation. The airrighting reflex and reappearance at the water surface were examined. The success rate for airrighting of HG rats is 47% versus 45% for controls, and is performed about equally fast by both groups. The success rate of HG and control hamsters is </=25% and >/=80%, respectively [22]. This interspecific difference does not appear to support the conjecture that altered behaviour is caused by a structural change of vestibular end organs during ontogenetic development under HG. The success rate for surfacing of control rats is 100%. Surfacing of young HG rats is less successful (36% at age 6 weeks) and requires more time. On average, surfacing of adult rats of both groups is about the same. Apparently, the repeated stay of centrifuge-bred rats at 1 g for experiments and daily care suffices to recalibrate and improve their orientation, which is essential for surfacing.
Wubbels
R J
RJ
Vestibular Department ENT, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. r.j.wubbels@amc.uva.nl
de Jong
H A
HA
D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D001835:Body Weight / Q000502:physiology; D005260:Female; D018471:Hypergravity; D008297:Male; D009949:Orientation / Q000502:physiology; D011187:Posture / Q000502:physiology; D051381:Rats; D020318:Rats, Long-Evans; D012018:Reflex / Q000502:physiology; D013550:Swimming / Q000502:physiology; D014722:Vestibule, Labyrinth / Q000502:physiology*