Induction of c-fos mRNA in rat brain by conditioned and unconditioned stressors.
Intense depolarizing stimuli induce the expression of the proto-oncogene c-fos which may be useful as a marker of neuronal activity. To determine if mild physical and behavioral stressors may also induce c-fos expression, we subjected rats to an unconditioned stressor (footshock) or a conditioned stressor (a tone previously paired with footshock) and measured c-fos mRNA levels in various brain regions using in situ hybridization. Removing rats from their home cage and exposing them to a tone was sufficient to cause increases in c-fos mRNA in several forebrain areas while further increases in c-fos occurred in the septum, cingulate cortex, and endopiriform nucleus in response to acute footshock stress. Both unconditioned and conditioned stressors increased c-fos mRNA levels in the locus ceruleus which correlated with stress-induced plasma corticosterone concentrations. Unconditioned footshock stress also increased c-fos mRNA in the hypothalamic paraventricular nucleus (PVN). However, neither conditioned nor unconditioned stressors induced c-fos in the PVN in rats which had been previously exposed to footshock. C-fos appears to be a sensitive marker for stress-responsive brain areas and may be important in mediating long-term neurochemical changes that result from stress.
Smith
M A
MA
Clinical Neuroendocrinology Branch, NIMH/NIH, Bethesda, MD 20892.
Banerjee
S
S
Gold
P W
PW
Glowa
J
J
D000161:Acoustic Stimulation; D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000502:physiology*; D003345:Corticosterone / Q000097:blood; D004597:Electroshock; D016762:Genes, fos; D008297:Male; D009928:Organ Specificity; D016548:Prosencephalon / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013315:Stress, Psychological / Q000503:physiopathology*; D013462:Sulfur Radioisotopes
D012333:RNA, Messenger; D013462:Sulfur Radioisotopes; D003345:Corticosterone