[csda] Formaldehyde produces fear in male rats (fwd)

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Subject: [csda] Formaldehyde produces fear in male rats

Brain Res. 2004 May 15;1008(1):11-9.

Repeated low level formaldehyde exposure produces enhanced fear

conditioning to odor in male, but not female, rats.

Sorg BA, Swindell S, Tschirgi ML.

Alcohol and Drug Abuse Program and Program in Neuroscience,

Department of VCAPP, Washington State University, Pullman, WA 99164-

6520, USA. barbsorg@...

Multiple chemical sensitivity (MCS) is an ill-defined disorder in

humans attributed to exposure to volatile organic compounds. This

study draws on apparent parallels between individuals with

posttraumatic stress disorder (PTSD) and panic disorder and a subset

of those reporting MCS, using a conditioned fear task in rats. Male

and female Sprague-Dawley rats were given repeated exposure to 2 ppm

formaldehyde (Form) (1 h/day x 5 days/week x 4 week) or air, and

after 2-3 weeks, rats were trained on the conditioned fear task. One

half of Air and Form rats were given odor (orange oil, the

conditioned stimulus, CS) paired with footshock (PRD) and the other

half was given the same stimuli in an unpaired manner (UNP). After 24

h, rats were placed into the same context without the CS or

footshock. Male and female PRD groups demonstrated contextual

freezing 5-15% of the time, while the UNP groups showed freezing 30-

50% of the time, with no effect of Air or Form pretreatment. For the

next 5 days, rats were placed into a novel context and tested for

freezing in the absence or presence of the CS. In male rats, Form

pretreatment produced a significantly greater freezing response in

both UNP and PRD groups in the presence of the CS, with no

differences in freezing in the absence of the CS. In female rats, no

significant differences between Form pretreated rats and Air controls

were observed in either the PRD or UNP groups. The increase in

conditioned fear responding to the CS after Form exposure in males

suggests that repeated low-level Form may act as a stressor to

produce sensitized responding within olfactory/limbic pathways, and

may help explain the panic-like responses observed in a subset of

individuals reporting MCS. Furthermore, the male/female differences

suggest a gonadal hormonal contribution to this behavior.

PMID: 15081377 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

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