The role of hypothalamic input on corticotroph maturation in fetal sheep.
Corticotropin-releasing hormone receptor type 1 (CRH-R1) expression and vasopressin type 1b (V1b) receptor protein decrease in late-gestation fetal sheep. Because hypothalamo-pituitary disconnection (HPD) has been demonstrated to prevent the morphological maturation of corticotrophs, we hypothesized that hypothalamic input is necessary for the maturational changes in CRH-R1 and V1b receptor levels. We measured CRH-R1 and V1b receptor expression in the anterior pituitaries of fetuses at 140 days gestational age (dGA) that underwent HPD or sham surgery at 120 dGA. CRH-R1 mRNA decreased similarly in HPD and sham-operated fetuses compared with 120 dGA naive fetuses. However, CRH-R1 protein levels were elevated in HPD fetuses compared with sham and were not different from 120 dGA values. V1b protein levels decreased similarly in HPD and sham-operated fetuses compared with 120 dGA naive fetuses. We conclude that hypothalamic input to the pituitary is necessary for the decrease in CRH-R1 receptor protein levels in late-gestation fetal sheep. However, hypothalamic input is not necessary for the decrease in V1b receptor expression seen in late gestation.
Young
Sharla F
SF
Department of Physiology/Pharmacology, Excellence in Cardiovascular Sciences Summer Program, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
Tatter
Stephen B
SB
Valego
Nancy K
NK
Figueroa
Jorge P
JP
Thompson
Jalonda
J
Rose
James C
JC
D000818:Animals; D001784:Blood Gas Analysis; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005333:Fetus / Q000166:cytology* / Q000294:innervation*; D005786:Gene Expression Regulation; D006854:Hydrocortisone / Q000097:blood; D007031:Hypothalamus / Q000502:physiology*; D010903:Pituitary Gland, Anterior / Q000166:cytology* / Q000378:metabolism*; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018019:Receptors, Corticotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism; D017483:Receptors, Vasopressin / Q000235:genetics / Q000378:metabolism; D034561:Sheep, Domestic
D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone; D017483:Receptors, Vasopressin; D006854:Hydrocortisone