PubMed Health⌕ Search

Biomedical subjects

S M Winston

Publications and source records attributed to S M Winston.

5 recordsLinked to original sources
PubMed1992

Amygdala kindling potentiates seizure-stimulated immediate-early gene expression in rat cerebral cortex.

Kindling induces long-term adaptations in neuronal function that lead to a decreased threshold for induction of seizures. In the present study, the influence of amygdala kindling on levels of mRNA for the immediate-early genes (IEGs) c-fos, c-jun, and NGF1-A were examined both before and after an acute electroconvulsive seizure (ECS). Although amygdala kindling did not significantly influence resting levels of c-fos mRNA in cerebral cortex, ECS-stimulated levels of c-fos mRNA (examined 45 min after ECS) were approximately twofold greater in the cerebral cortex of kindled rats relative to sham-treated controls. The influence of kindling on IEG expression was dependent on the time course of kindling, as ECS-stimulated levels of c-fos mRNA were not significantly increased in stage 2 kindled animals. ECS-stimulated levels of c-jun and NGF1-A mRNA were also significantly increased in cerebral cortex of kindled rats relative to sham-treated controls. The influence of kindling on IEG expression was long-lasting because an acute ECS stimulus significantly elevated levels of c-fos and c-jun mRNA in the cerebral cortex of animals that were kindled 5 months previously. In contrast to these effects in cerebral cortex, kindling did not influence ECS-stimulated levels of c-fos mRNA in hippocampus. Finally, immunohistochemical studies revealed lamina-specific changes in the cerebral cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Amygdala↗
PubMed1990

Chronic electroconvulsive seizures down-regulate expression of the immediate-early genes c-fos and c-jun in rat cerebral cortex.

Acute seizures and other stimuli that increase neuronal activity cause a rapid induction of the immediate-early genes c-fos and c-jun, also referred to as nuclear proto-oncogenes, in the nervous system. In the present study, rats were administered one or more electroconvulsive seizures (ECS) and the responsiveness of c-fos and c-jun to an acute, "test" seizure was examined. Four hours after a single ECS, the induction of c-fos mRNA by a test seizure was blocked, in agreement with earlier findings, but by 18 h the levels of c-fos mRNA could be reinduced by the test seizure, suggesting that 1 day is sufficient to "reset" the responsiveness of this system. However, it was found that chronic, daily ECS treatments resulted in a time-dependent decrease in the expression of c-fos mRNA in response to a test seizure administered 18 h after the last daily ECS; this effect was maximal after 8-10 days of treatment, at which time the induction of c-fos mRNA by the test seizure was blocked dramatically. Chronic ECS also blocked the induction of c-jun in response to an acute, test seizure. The effect of chronic ECS on levels of Fos protein was also investigated. It was found that basal levels of Fos protein were reduced after chronic (10 days) ECS and were not induced by a test seizure. Because levels of Fos protein remain elevated 4 h after a single seizure this finding suggests that the mechanisms by which acute (4 h) and chronic (8-10 days) ECS block the induction of c-fos may differ.

Animals↗
PubMed1990

Corticosterone regulates the expression of ADP-ribosylation factor messenger RNA and protein in rat cerebral cortex.

ADP-ribosylation factors (ARFs) comprise a family of small GTP-binding proteins found in brain and other tissues. Recent studies have demonstrated that the expression of the larger heterotrimeric guanine nucleotide binding proteins is under control by steroid hormones. Therefore, in the present study, we examined the influence of glucocorticoids on the expression of ARF mRNA and protein. using specific cDNA probes and antisera, respectively. Chronic administration of corticosterone (7 days) significantly increased levels of mRNA for ARF1 and ARF3, two subtypes of ARF, in rat cerebral cortex. Chronic administration of corticosterone was also found to increase levels of ARF immunoreactivity in this brain region. However, 1-day administration of corticosterone did not influence levels of mRNA for either ARF1 or ARF3. In contrast to corticosterone, bilateral adrenalectomy (7 days after surgery) was found to decrease ARF1 and ARF3 message relative to sham controls; this effect of adrenalectomy was reversed by corticosterone treatment. These results demonstrate that the expression of ARF is under hormonal control and may underlie aspects of glucocorticoid action on neuronal function.

ADP-Ribosylation Factor 1↗