Human dermal fibroblast cells express prolactin in vitro

Area of Science:

• Endocrinology
• Dermatology
• Cell Biology

Background:

• Prolactin (PRL) is a key hormone primarily produced by the pituitary gland.
• The presence and function of PRL within the skin have not been fully elucidated.
• Dermal fibroblasts represent a potential non-pituitary source of PRL.

Purpose of the Study:

• To investigate the synthesis and release of prolactin from human dermal fibroblasts in vitro.
• To identify factors that modulate prolactin release from these cells.
• To characterize the nature of fibroblast-derived prolactin.

Main Methods:

• Culturing of dermal fibroblasts from diverse age groups and sexes.
• Measurement of prolactin release using established assays.
• Treatment with various agents including medroxyprogesterone acetate, estradiol, prostaglandin E2, and dibutyryl-cyclic AMP.
• Analysis of cell proliferation and DNA content.
• Immunological and electrophoretic characterization of fibroblast PRL.
• Northern blot analysis for PRL mRNA detection.

Main Results:

• Dermal fibroblasts (>98% purity) demonstrated in vitro synthesis and release of prolactin.
• PRL release was detected by day 18 in confluent cultures, peaking at 2 ng/72 h by day 30.
• Prostaglandin E2 (PGE2) significantly reduced the induction time for PRL release to 6-9 days.
• Synergistic effects were observed with PGE2 and steroids (medroxyprogesterone acetate, estradiol), increasing maximal release to ~10 ng/72 h.
• Dibutyryl-cyclic AMP, alone or with steroids, further enhanced PRL release, reaching up to 32 ng/72 h.
• Increased PRL release was not due to enhanced cell proliferation; PRL-secreting cultures showed reduced DNA content.
• Fibroblast PRL was immunologically and electrophoretically identical to pituitary and decidual PRL, with a 1.15 kb mRNA size.
• Maximal PRL release reached 32.0 ± 6.1 ng/72 h across a broad age range (20-week gestation to 52 years).

Conclusions:

• Human dermal fibroblasts represent a significant local source of prolactin within the skin.
• The release of prolactin from dermal fibroblasts can be modulated by prostaglandin E2 and steroid hormones.
• Fibroblast-derived prolactin shares characteristics with pituitary and decidual prolactin, suggesting a conserved functional role.
• These findings open new avenues for understanding prolactin's local functions in skin physiology and pathology.