| Abstract No.: | B-E2171 |
| Country: | Canada |
| | |
| Title: | THE EFFECTS OF CORTICOSTERONE MANIPULATION ON THE EXPRESSION OF THE CLOCK PROTEIN, PERIOD2, IN THE CENTRAL EXTENDED AMYGDALA OF ADRENALECTOMIZED AND INTACT RATS |
| | |
| Authors/Affiliations: | 1 Lauren Segall*; 1 Shimon Amir;
1 Concordia University, Montreal, QC, Canada
|
| | |
| Content: | Objectives: Rhythmic oscillations of the clock protein PERIOD2 (PER2) in the oval nucleus of the bed nucleus of the stria terminalis (BNSTov) and the central nucleus of the amygdala (CEA) are contingent upon diurnal variations of the circadian-driven adrenal hormone corticosterone (CORT), implicating CORT as a mechanism by which the master clock communicates with subordinate oscillators. The aim of this study was to determine the effects of stress hormone manipulation on the expression PER2 in these regions of the brain that are sensitive to stress and anxiety.
Materials and methods: All animals (n=3 to 4/group/timepoint) were entrained for two weeks to a 12hr light/12hr dark schedule, then killed at four time-points: zeitgeber time (ZT) 1, 7, 13, and 19, where ZT 0 denotes lights on and ZT 13 denotes one hour after lights off. Brains were removed, sliced, and stained for PER2 immunoreactivity.
Bilaterally adrenalectomized (ADX) rats and adrenally intact rats received ten days of either CORT or distilled water injections s.c. at ZT 0 (10mg/kg).
Adrenally intact rats received one day of either CORT or distilled water injections at ZT 0 (10mg/kg).
Results: ADX rats subjected to serial CORT injections show an elevation of PER2 immunoreactivity in the BNSTov and CEA at ZT1 compared to controls, resulting in an induction of PER2 rhythmicity peaking in the morning.
Intact rats subjected to serial CORT injections show an elevation of PER2 immunoreactivity at ZT1 and an overall attenuation of the daily rhythm in the BNSTov and CEA compared to controls.
Intact rats subjected to acute CORT administration show no significant shift in PER2 expression.
Other forebrain regions examined included the suprachiasmatic nucleus (SCN), the basolateral amygdala (BLA) and the dentate gyrus (DG). PER2 expression in these areas is invulnerable to ADX and did not show any effects of CORT administration.
Conclusion: Our results show that PER2 expression in central clocks that are important in stress and anxiety is sensitive to fluctuations in circulating CORT. This underscores the importance of proper glucocorticoid signaling and highlights how disruption of the daily CORT rhythm alters the functionality and possibly the behavioural output of these clocks
|
| | |
| Back |
|
