Chronic glucocorticoid administration as well as repeated stress affects the subsequent acute immobilization stress-induced expression of immediate early genes but not that of NGFI-A.
We reported that repeated immobilization for six days attenuates the subsequent acute immobilization stress-induced expression of the immediate early genes c-fos, fos B, jun B and nerve growth factor-induced gene-B (NGFI-B), but not of NGFI-A, in the rat paraventricular hypothalamic nucleus. In this study, we confirmed these findings by means of a time-course study, and further investigated whether the elevated plasma basal glucocorticoid level induced by repeated stress underlies the attenuated response of immediate early genes and the preserved reactivity of NGFI-A. Rats implanted with 100, 200 or 400 mg corticosterone or placebo pellets (control), were immobilized for 1 h and decapitated seven days later. In control rats acute immobilization induced c-fos, fos B, jun B, NGFI-A and NGFI-B messenger RNA in the paraventricular hypothalamic nucleus, whereas all of them except NGFI-A, were significantly reduced in rats given 200 and 400 mg corticosterone implants. The similarity of the results from the two procedures suggests that glucocorticoid is involved in regulating immediate early genes in the paraventricular hypothalamic nucleus under repeated stress and that the NGFI-A gene is not regulated by this mechanism. However, the plasma basal corticosterone level in repeatedly stressed rats was lower than that of rats implanted with 100 mg corticosterone, suggesting that a repetitive stress-induced corticosterone surge also contributes to this mechanism.
Umemoto
S
S
Department of Anatomy and Neurobiology, Wakayama Medical College, Wakayama City, Japan.
Kawai
Y
Y
Ueyama
T
T
Senba
E
E
D000818:Animals; D003345:Corticosterone / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D051766:Early Growth Response Protein 1; D005786:Gene Expression Regulation / Q000187:drug effects; D017781:Genes, Immediate-Early; D005938:Glucocorticoids / Q000494:pharmacology*; D017874:Immediate-Early Proteins; D007700:Kinetics; D008297:Male; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis; D011987:Receptors, Steroid; D012149:Restraint, Physical; D013315:Stress, Psychological / Q000378:metabolism*; D014157:Transcription Factors / Q000096:biosynthesis*; D014158:Transcription, Genetic / Q000187:drug effects; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D005938:Glucocorticoids; D017874:Immediate-Early Proteins; C539820:Nr4a1 protein, rat; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D014157:Transcription Factors; D003345:Corticosterone