At least three neurotransmitter systems mediate a stress-induced increase in c-fos mRNA in different rat brain areas.
1. Protooncogene c-fos mRNA levels were determined in the rat cerebral cortex, hippocampus, and cerebellum after exposure to a combined forced swimming and confinement stress. The stress resulted in an increase in c-fos mRNA levels in all three brain areas. 2. In an effort to elucidate the neurotransmitter systems involved in this stress-induced increase, animals were injected, prior to exposure to the stress, with either diazepam, MK-801, or propranolol. 3. In both the cerebral cortex and the hippocampus the stress-induced increase in c-fos mRNA was inhibited by MK-801, suggesting that it is mediated via NMDA receptors. In the hippocampus, propranolol had a similar effect, indicating that beta-adrenergic receptors are also involved in the stress-induced increase in c-fos mRNA. 4. On the other hand, the increase in c-fos mRNA produced by the stress of the injection was inhibited in the cerebral cortex by diazepam or propranolol and in the hippocampus only by diazepam. Furthermore, administration of MK-801 resulted in an increase in c-fos mRNA in the hippocampus of the nonstressed animals. In the cerebellum no one of the three drugs employed affected c-fos mRNA levels in either stressed or nonstressed animals. 5. Our results thus show that various forms of stress activate, in different brain areas, neurons with either NMDA, beta-adrenergic, and/or GABA-A receptors.
Bozas
E
E
Laboratory of Biology-Biochemistry, Faculty of Nursing, University of Athens, Greece.
Tritos
N
N
Phillipidis
H
H
Stylianopoulou
F
F
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D003975:Diazepam / Q000494:pharmacology; D016291:Dizocilpine Maleate / Q000494:pharmacology; D016762:Genes, fos; D006624:Hippocampus / Q000378:metabolism; D008297:Male; D018377:Neurotransmitter Agents / Q000502:physiology*; D009928:Organ Specificity; D011433:Propranolol / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D012149:Restraint, Physical; D013315:Stress, Psychological; D013550:Swimming; D014158:Transcription, Genetic / Q000187:drug effects
D018377:Neurotransmitter Agents; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D016291:Dizocilpine Maleate; D011433:Propranolol; D003975:Diazepam