H Phillipidis | PubMed Health

PubMed1998

Beta-adrenergic receptors mediate a stress-induced decrease in IGF-II mRNA in the rat cerebellum.

1. Exposure to a combined forced swimming-confinement stress resulted in a decrease in insulin-like growth factor II (IGF-II) mRNA levels in the whole brain (without the cerebellum) and in the isolated brain areas of the cerebral cortex, the hippocampus, and the cerebellum. 2. In an effort to elucidate the neurotransmitter systems involved in this stress-induced decrease, animals were injected prior to exposure to the stress, with either propranolol, diazepam, or MK-801. 3. Administration of diazepam or MK-801 did not affect the stress-induced decrease in IGF-II mRNA in any of the three brain areas examined. 4. Administration of propranolol prior to the exposure to the stress inhibited the stress-induced decrease in IGF-II mRNA in the cerebellum. Propranolol had no such effect in the cerebral cortex or the hippocampus. 5. Our results suggest that in the cerebellum, the stress-induced decrease in IGF-II mRNA is mediated by beta 2-adrenergic receptors.

Adrenal Cortex Hormones↗

PubMed1997

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.

Animals↗