Prolactin crinophagy is induced in the estrogen-stimulated male rat pituitary.
The phenomenon of crinophagy in rat pituitary mammotrophs, or lysosomal uptake of prolactin secretory granules, was confirmed by means of double-label immunogold electron microscopy, and shown to be induced in estrogen-stimulated male rats. Rabbit antibodies to rat cathepsin D were used to label lysosomes, and to rat prolactin to label secretory granules. The pituitaries were fixed in 4% formaldehyde and 1% glutaraldehyde, embedded in Lowicryl K4M, and thin sections were exposed successively to primary antibodies, biotin-labelled second antibodies, and streptavidin-gold, with an amplification procedure for cathepsin D. Cathepsin D and prolactin were detected separately on opposite sides of the sections, using 5-nm and 15-nm gold particles. Lysosomal uptake of prolactin secretory granules was not observed in untreated control rats. It was detected in about 26% of lysosome-containing mammotroph cell sections in estrogen-stimulated rats and at 7 h after estrogen withdrawal, but fell to 14% at 24 h and to 2% at 72 h after estrogen withdrawal.
Kuriakose
N R
NR
Department of Anatomy, Queen's University, Kingston, Ontario, Canada.
Reifel
C W
CW
Bendayan
M
M
Elce
J S
JS
Shin
S H
SH
D000818:Animals; D002402:Cathepsin D / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D007150:Immunohistochemistry; D008247:Lysosomes / Q000378:metabolism*; D008297:Male; D010587:Phagocytosis; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D004958:Estradiol; D011388:Prolactin; D002402:Cathepsin D