Bovine pars tuberalis secretions release growth hormone from rat pars distalis of pituitary gland.
The pituitary pars tuberalis (PT) is characterized by PT-specific secretory cells which have raised the possibility of an endocrine function for this portion of adenohypophysis.


OBJECTIVE
To investigate the effect of the secretion of bovine PT cells into culture medium on growth hormone (GH) response of dispersed pars distalis (PD) cells of rats.


RESULTS
48-hour culture medium of all PT cells at 1 microg of protein concentration induced the greatest GH release from PD cells. After PT cells separation on a discontinuos Percoll gradient and culturing, only the culture medium of cells from 50 and 60% Percoll strength released GH from PD cells. Therefore, cells from 50 and 60% strenght Percoll were cultured together. Only 0.2 mg protein of this culture medium was required to induce the maximal GH release from PD cells, suggesting that these cells could be responsible for producing the factor(s) which affect PD somatotrophe cells. After protein separation by 12% SDS-PAGE of this PT culture medium bands were eluted. The biological activity, measured as ng/ml of GH from PD cells, corresponded to a protein(s) of molecular weight between 45 and 66 kDal.


CONCLUSIONS
The results indicate that there is an active proteic factor(s) secreted by the PT that acts upon PD cells to stimulate GH release and that PD could be an effector organ for some secretory product(s) of the PT.
Lafarque
Martha María
MM
Laboratorio de Biología de la Reproducción (LABIR), Departamento de Bioquímica y Ciencias Biológicas, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, San Luis, Argentina.
Ezquer
Marcelo
M
Aguado
Luis Inocencio
LI
Oliveros
Liliana Beatriz
LB
D000818:Animals; D001685:Biological Factors / Q000502:physiology*; D002417:Cattle; D002469:Cell Separation; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D013006:Growth Hormone / Q000378:metabolism*; D008297:Male; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D001685:Biological Factors; D017077:Culture Media, Conditioned; D013006:Growth Hormone