Role of locally produced growth hormone-releasing factor in somatostatin regulation by fetal rat brain cells in culture.
To determine the possible physiological role of endogenous growth hormone-releasing factor (GRF) in the neuronal content and release of cerebral somatostatin (SS), we studied the effect of endogenous GRF blockade on the immunoreactive SS (IR-SS) content of cells and media in fetal rat cerebral cortical and hypothalamic cells in culture. Cells were cultured in minimum essential medium (MEM) with 10% fetal calf serum and 10% horse serum. After 7-10 days in vitro, media were replaced with MEM without sera containing anti-GRF immunoglobulins G (IgG) for 1, 5 or 24 h. Controls were incubated with equal amounts of IgG from normal rabbit serum (NRS). In another group of experiments, cells were incubated with GRF (10(-11) to 10(-7) M) for 1 or 24 h. Long-term exposure (24 h) to anti-GRF IgG resulted in decreased media and intracellular IR-SS content, in both cerebral cortical and hypothalamic cells. 24 h treatment with GRF caused a dose-dependent increase in the IR-SS content of cells and media, the stimulatory action being abolished by the addition of anti-GRF to plates containing 10(-7) M GRF. On the contrary, when cells were exposed to anti-GRF IgG for 1 h, IR-SS increased in the media as compared to the control group. Short-term incubation (1 h) with GRF (10(-9) to 10(-7) M) resulted in a dose-dependent inhibition of IR-SS content in the cells and media. This inhibitory action was partially prevented by the addition of anti-GRF to plates containing 10(-7) M GRF.(ABSTRACT TRUNCATED AT 250 WORDS)
Servicio de Endocrinología, Hospital Ramón y Cajal, Madrid, Spain.
M T
MT
de los Frailes
L
L
Cacicedo
G
G
Fernandez
R M
RM
Tolón
M
M
Jesus Lorenzo
F
F
Aguado
F
F
Sánchez Franco
D000818:Animals; D001921:Brain / Q000196:embryology / Q000502:physiology*; D002478:Cells, Cultured; D005314:Embryonic and Fetal Development / Q000502:physiology; D013007:Growth Hormone-Releasing Hormone / Q000276:immunology / Q000502:physiology*; D007074:Immunoglobulin G / Q000302:isolation & purification; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000502:physiology*
D007074:Immunoglobulin G; D013004:Somatostatin; D013007:Growth Hormone-Releasing Hormone