Prolactin-induced regression of the rat corpus luteum: expression of monocyte chemoattractant protein-1 and invasion of macrophages.
Monocyte chemoattractant protein-1 (MCP-1) is a potential mediator of the recruitment of monocytes/macrophages into the regressing corpus luteum (CL). We investigated whether the luteolytic effect of prolactin in the rat is associated with the expression of MCP-1 and an invasion of monocytes/macrophages. Ovulation was induced in immature female rats by injection of eCG (5 IU, s.c.) at 30 days of age. All rats were hypophysectomized 3 days later. Rats received injections of ovine prolactin (250 micrograms, s.c.) at 12-h intervals on Day 9, 10, and 11 posthypophysectomy; controls received injection of vehicle. Rats were killed by decapitation 24, 48, or 72 h after the first injection of prolactin or vehicle. In rats treated with prolactin, immunoreactive MCP-1 was detected in the CL at 24 h after the first injection, and a consistent level of staining was reached by 72 h with immunodetectable MCP-1 diffused throughout individual CL. The number of monocytes/macrophages in the CL (mean +/- SEM) increased significantly after prolactin treatment, from 3.1 +/- 1.8 at 24 h to 49.3 +/- 8.2 at 72 h (p < 0.05), and the number of monocytes/macrophages was different from that in control, vehicle-treated rats at 72 h (10.3 +/- 4.1; p < 24 and 72 h in prolactin-treated rats (p < 0.05). It is concluded that a potentially important component of the luteolytic effect of prolactin in the rat is the expression of MCP-1 and invasion of monocytes/macrophages into the CL.
Bowen
J M
JM
Department of Physiology, University of Michigan Medical School, Ann Arbor 48109-0622, USA.
Keyes
P L
PL
Warren
J S
JS
Townson
D H
DH
D004092:20-alpha-Dihydroprogesterone / Q000097:blood; D000818:Animals; D018932:Chemokine CCL2 / Q000032:analysis / Q000378:metabolism*; D003338:Corpus Luteum / Q000166:cytology / Q000502:physiology*; D005260:Female; D007016:Hypophysectomy; D007150:Immunohistochemistry; D003341:Luteolysis / Q000187:drug effects*; D008264:Macrophages / Q000502:physiology*; D010062:Ovulation Induction; D011388:Prolactin / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D018932:Chemokine CCL2; D004092:20-alpha-Dihydroprogesterone; D011388:Prolactin