Repeated exposure attenuates the behavioral response of rats to static high magnetic fields.
Exposure of rats to high strength static magnetic fields of 7 T or above has behavioral effects such as the induction of locomotor circling, the suppression of rearing, and the acquisition of conditioned taste aversion (CTA). To determine if habituation occurs across magnetic field exposures, rats were pre-exposed two times to a 14 T static magnetic field for 30 min on two consecutive days; on the third day, rats were given access to a novel 0.125% saccharin prior to a third 30-min exposure to the 14 T magnetic field. Compared to sham-exposed rats, pre-exposed rats showed less locomotor circling and an attenuated CTA. Rearing was suppressed in all magnet-exposed groups regardless of pre-exposure, suggesting that the suppression of rearing is more sensitive than other behavioral responses to magnet exposure. Habituation was also observed when rats underwent pre-exposures at 2-3h intervals on a single day. Components of the habituation were also long-lasting; a diminished circling response was observed when rats were exposed to magnetic field 36 days after 2 pre-exposures. To control for possible effects of unconditioned stimulus pre-exposure, rats were also tested in a similar experimental design with two injections of LiCl prior to the pairing of saccharin with a third injection of LiCl. Pre-exposure to LiCl did not attenuate the LiCl-induced CTA, suggesting that 2 pre-exposures to an unconditioned stimulus are not sufficient to explain the habituation to magnet exposure. Because the effects of magnetic field exposure are dependent on an intact vestibular apparatus, and because the vestibular system can habituate to many forms of perturbation, habituation to magnetic field exposure is consistent with mediation of magnetic field effects by the vestibular system.
Houpt
Thomas A
TA
Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, FL 32306-4340, USA. houpt@neuro.fsu.edu
Cassell
Jennifer A
JA
Hood
Alison
A
DenBleyker
Megan
M
Janowitz
Ilana
I
Mueller
Kathleen
K
Ortega
Breyda
B
Smith
James C
JC
D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000818:Animals; D001362:Avoidance Learning / Q000528:radiation effects; D001522:Behavior, Animal / Q000528:radiation effects*; D003213:Conditioning, Psychological / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004574:Electromagnetic Fields / Q000009:adverse effects*; D005260:Female; D005518:Food Preferences / Q000528:radiation effects; D018021:Lithium Chloride / Q000008:administration & dosage; D009043:Motor Activity / Q000528:radiation effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012439:Saccharin / Q000008:administration & dosage; D013549:Sweetening Agents / Q000008:administration & dosage; D013997:Time Factors
D000276:Adjuvants, Immunologic; D013549:Sweetening Agents; D012439:Saccharin; D018021:Lithium Chloride