Long-Term Potential: Role of Hippocampal Adrenal Steroid Type I and II Receptors in the Diurnal Rhythm and the Impact of Stress
Annual rept. 1 Dec 1992-30 Nov 1993
ROCKEFELLER UNIV NEW YORK
Pagination or Media Count:
Adrenal steroid secretion during the sleep-waking cycle coordinates brain. function and cognitive activity with metabolism and other basic body functions, and it also mediates the adaptive and restorative effects of stress. Jet lag represents a disordering of diurnal adrenocortical activity as well as a form of stress. We are studying the actions of adrenal steroids in hippocampus of living, animals on long-term potentiation LTP and long-term depression LTD, two forms of neurophysiological plasticity related to learning, and we are searching for some of the molecular and structural changes associated with it. Adrenal steroids biphasically modulate LTP via intracellular Type I and Type II receptors, and these effects are seen in both anaesthetized and awake-freely moving animals. LTP that is increased by Type I receptor activation lasts for at least 24h and is greater than in adrenalectomized rats. LTP is suppressed by Type II receptor activation, and LTD, can also result from this activation. Current studies are investigating immediate early gene mainly JUN induction by steroids and LTP and LTD, and we also plan to look for changes in structural gene products such as GAP-43 that may be indicative of synaptogenesis.
- Stress Physiology