Development of the sex difference in glandular kallikrein and prolactin levels in the anterior pituitary of the rat

Glandular kallikrein is a major estrogen-induced and dopamine-repressed protein of the rat anterior pituitary that appears to originate from lactotrophs. This study examined the development of glandular kallikrein levels in the anterior pituitary in both female and male rats and compared it to anterior pituitary prolactin. In addition, the development of glandular kallikrein levels in the neurointermediate lobe of the pituitary and the kidney were also examined. During puberty, a dramatic surge in glandular kallikrein occurred in female anterior pituitaries (16- to 20-fold increase) and levels remained elevated thereafter. The dynamics of the increase were biphasic--glandular kallikrein increased between Day 30 and 45, plateaued between Days 45 and 55, and then increased again between Days 55 and 65. Female anterior pituitary prolactin increased 7- to 8-fold during puberty. The rise during puberty was biphasic and was generally synchronized with increases in glandular kallikrein. However, the initial rise was proportionately less than that of glandular kallikrein, and the secondary surge was more dramatic. In contrast to females, anterior pituitary glandular kallikrein remained at low levels in male rats; prolactin levels also remained unchanged through puberty and increased moderately thereafter. Glandular kallikrein in the female neurointermediate lobe remained unchanged through Day 55, almost doubled on Day 60, and returned to prepubertal levels by Day 65; males did not exhibit the transient surge in neurointermediate lobe levels. Starting at age 60 days, renal glandular kallikrein was found to be slightly higher (15-20%) in females than in males.(ABSTRACT TRUNCATED AT 250 WORDS)