Upregulated expression of neuropeptide Y in hypothalamic-pituitary system of rats by chronic dexamethasone administration.
To study the effect of adrenal steroids on neuropeptide Y (NPY) synthesis in the hypothalamic-pituitary system, we examined NPY expression in rats treated with dexamethasone (a synthetic glucocorticoid) by in situ hybridization and immunohistochemistry. Rats were injected daily with dexamethasone (0.2mg/100g/day for 10 days, sc) or sesame oil (vehicle control), or non-injected (intact control). Relative staining area for corticotropin-releasing hormone or neurophysin II, a vasopressin carrier protein, was increased in the external zone of the median eminence in vehicle control, but was equivalent to that of intact control in the dexamethasone-injected group. Density of NPY-stained fiber varicosities was drastically increased in the external, but not the internal, zone of dexamethasone-injected group, coinciding with the increased NPY hybridization signal level in the arcuate nucleus. Dual-labeling experiments revealed no colocalization of NPY with hypophysiotropic or other peptides examined in single fibers of the median eminence. In the dexamethasone-injected group, expressions of NPY mRNA and peptide were detectable in a few pituitary cells, with some being corticotropes. These results suggest that NPY plays hormonal roles in the hypothalamic-pituitary-adrenal axis.
Konno
Jinko
J
Laboratory of Neuroendocrinology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8574, Japan.
Yoshida
Sachine
S
Ina
Ayuka
A
Ohmomo
Hideki
H
Shutoh
Fumihiro
F
Nogami
Haruo
H
Hisano
Setsuji
S
D054369:Agouti-Related Protein / Q000378:metabolism; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D005938:Glucocorticoids / Q000494:pharmacology*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects* / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D008473:Median Eminence / Q000187:drug effects / Q000502:physiology; D009478:Neuropeptide Y / Q000235:genetics* / Q000378:metabolism; D009481:Neurophysins / Q000378:metabolism; D010902:Pituitary Gland / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
C515197:AGRP protein, rat; D054369:Agouti-Related Protein; D005938:Glucocorticoids; D009478:Neuropeptide Y; D009481:Neurophysins; D012333:RNA, Messenger; D003907:Dexamethasone; D003346:Corticotropin-Releasing Hormone