J Korean Neurosurg Soc.  1999 Sep;28(9):1264-1271.

An Experimental Study of Effects of Nitric Oxide Synthase on Rat Anterior Pituitary Gland

• Lee HK
• Hwang DY
• Kim YW
• Park YK
• Yang MH

Abstract

OBJECTIVE
The nitric oxide synthases(NOS) are a group of isoenzymes that convert L-arginine to L-citrulline and generate nitric oxide(NO). The constitutive form of NOS is present in endothelium, adrenal gland, brain, and platelets, while the inducible form of NOS is present in macrophages, hepatocytes, vascular smooth muscle cell and endothelial cells. To determine whether NO has a role in anterior pituitary cell function, immunohistochemistry and molecular techniques were used to study NOS expression in rat pituitary gland.
MATERIALS AND METHODS
We treated the rats with two NOS inhibitors: N-mono-methyl amine(NMMA), which is an inhibitor of NOS activity, and aminoguanidine, which a selective inhibitor of the inducible NOS isoform and two NO donors; sodium nitroprusside(SNP), s-nitro-acetyl-penicillamine(SNAP) as well as L-arginine. Rat growth hormone was measured in the serum using radioimmunoassay and NOS producing cells in the anterior lobe of the pituitary was detected by immunohistochemical stains. Also mRNA was extracted from the pituitary and performed RT-PCR using inducible NOS primer.
RESULTS
Serum growth hormone levels were increased significantly by administration of NOS inhibitors, such as NMMA and aminoguanidine. Immunohistochemical stains for neuronal and inducible NOS showed strong positivity in the folliculostellate cells and weak positivity in the anterior pituitary cells in the control and various experimental groups. RT-PCR in inducible NOS showed more brighter band in the 222 base pairs in the aminoguanidine treated group than normal control group.
CONCLUSION
These data suggest that pituitary NOS may play a pivotal role in the control of growth hormone secretion.

Keyword

Nitric oxide synthase; Pituitary; Immunohistochemistry; RT-PCR; Rat

MeSH Terms

Adrenal Glands
Animals
Arginine
Base Pairing
Brain
Coloring Agents
Endothelial Cells
Endothelium
Growth Hormone
Hepatocytes
Humans
Immunohistochemistry
Isoenzymes
Macrophages
Muscle, Smooth, Vascular
Neurons
Nitric Oxide Synthase*
Nitric Oxide*
Pituitary Gland
Pituitary Gland, Anterior*
Radioimmunoassay
Rats*
RNA, Messenger
Sodium
Tissue Donors
Arginine
Coloring Agents
Growth Hormone
Isoenzymes
Nitric Oxide
Nitric Oxide Synthase
RNA, Messenger
Sodium