In vivo correlation between c-Fos expression and corticotroph stimulation by adrenocorticotrophic hormone secretagogues in rat anterior pituitary gland.
In the anterior pituitary gland, c-Fos expression is evoked by various stimuli. However, whether c-Fos expression is directly related to the stimulation of anterior pituitary cells by hypothalamic secretagogues is unclear. To confirm whether the reception of hormone-releasing stimuli evokes c-Fos expression in anterior pituitary cells, we have examined c-Fos expression of anterior pituitary glands in rats administered with synthetic corticotrophin-releasing hormone (CRH) intravenously or subjected to restraint stress. Single intravenous administration of CRH increases the number of c-Fos-expressing cells, and this number does not change even if the dose is increased. Double-immunostaining has revealed that most of the c-Fos-expressing cells contain adrenocorticotrophic hormone (ACTH); corticotrophs that do not express c-Fos in response to CRH have also been found. However, restraint stress evokes c-Fos expression in most of the corticotrophs and in a partial population of lactotrophs. These results suggest that c-Fos expression increases in corticotrophs stimulated by ACTH secretagogues, including CRH. Furthermore, we have found restricted numbers of corticotrophs expressing c-Fos in response to CRH. Although the mechanism underlying the different responses to CRH is not apparent, c-Fos is probably a useful immunohistochemical marker for corticotrophs stimulated by ACTH secretagogues.
Takigami
Shu
S
Department of Anatomy, Jichi Medical University School of Medicine, Shimotsuke-Shi, Tochigi, Japan.
Fujiwara
Ken
K
Kikuchi
Motoshi
M
Yashiro
Takashi
T
D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D052680:Corticotrophs / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D052682:Lactotrophs / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010906:Pituitary Hormone-Releasing Hormones / Q000494:pharmacology; D011388:Prolactin / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological / Q000503:physiopathology
D010906:Pituitary Hormone-Releasing Hormones; D016760:Proto-Oncogene Proteins c-fos; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D003346:Corticotropin-Releasing Hormone