The thymulin-lactotropic axis in rodents: thymectomy, immunoneutralization and gene transfer studies.
OBJECTIVE
There is clear evidence on the existence of a thymus-pituitary axis which seems to be particularly important during perinatal life. In particular, the thymic peptide thymulin has been shown to be a relevant player in thymus-pituitary communication. Our goal was to explore the effect of thymulin on circulating prolactin (PRL) levels in different animal models. To this end we undertook a series of experiments in rats and mice, implementing adult thymectomy, thymulin immunoneutralization in normal C57BL/6 mice and neonatal thymulin gene therapy in nude mice.


METHODS
We assessed the impact of the above manipulations on PRL secretion and lactotrope morphology by measuring serum PRL by radioimmunoassay and by performing morphometric analysis of the lactotropic cell population in the anterior pituitary gland.


RESULTS
Adult thymectomy in female rats slightly increased serum PRL, an effect that was partially reversed by thymulin gene therapy. In mice, thymulin immunoneutralization from birth to age 32 days reduced serum PRL both in males and females. Thymulin immunoneutralization induced a significant (p < 0.01) decrease in lactotrope cell density (CD) and volume density (VD) without changes in cell size (CS). Neonatal thymulin gene therapy markedly increased serum thymulin (p < 0.01) and lactotrope CD, CS and VD in nude mice of both sexes.


CONCLUSIONS
Our findings suggest a modulatory effect of thymulin on the lactotrope cell population and on serum PRL, particularly during early life.
Department of Cytology, Histology and Embryology B, Faculty of Medicine, University of La Plata, La Plata, Argentina.
Eliana V
EV
Martines
Paula C
PC
Reggiani
Gisela
G
Camihort
Georgina
G
Luna
Maria F
MF
Zappa
Oscar A
OA
Brown
Rodolfo G
RG
Goya
Gloria M
GM
Cónsole
D000818:Animals; D000831:Animals, Newborn; D000906:Antibodies / Q000494:pharmacology / Q000627:therapeutic use*; D004195:Disease Models, Animal; D005260:Female; D015316:Genetic Therapy / Q000379:methods*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007775:Lactation Disorders / Q000235:genetics / Q000628:therapy*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D008822:Mice, Transgenic; D010902:Pituitary Gland / Q000378:metabolism / Q000473:pathology; D011388:Prolactin / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D013934:Thymectomy / Q000379:methods*; D013935:Thymic Factor, Circulating / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
D000906:Antibodies; D049452:Green Fluorescent Proteins; D011388:Prolactin; D013935:Thymic Factor, Circulating