Cytochrome P-45011 beta in rat brain.
The presence of cytochrome P-45011 beta in rat brain was studied by immunohistochemistry using polyclonal rabbit antibodies raised against purified bovine adrenocortical P-45011 beta, which is involved in the steroid 11 beta-hydroxylation and glucocorticoid formation. The results showed that cytochrome P-45011 beta immunoreactivity is selectively localized to the tracts of myelinated fibers throughout the brain. The specificity of immunohistochemical stainings with P-45011 beta antibodies was established by control tests including nonimmune rabbit immunoglobulin Gs and P-45011 beta antibodies absorbed with purified antigen. Western immunoblots of homogenates from different brain areas with P-45011 beta antibodies, together with biochemical enzymatic assays for cytochrome P-45011 beta monooxygenase activity in these homogenates, confirmed the selective localization of this enzyme observed with immunohistochemistry. Cytochrome P-45011 beta and 11 beta-hydroxylase activity were detected in a homogenate from the cortical white matter (brain area rich in myelinated fibers) as in that from the rat adrenal, but were not detectable in a homogenate from the cerebral cortex (brain area poor in myelinated fibers). Furthermore, quantitation of the P-45011 beta bands on the immunoblots by the areal density revealed that the cortical white matter contains approximately 1.4 pmol of cytochrome P-45011 beta/mg of tissue protein, the value of which was about one sixth of the corresponding value estimated in the rat adrenal. This relatively high content of cytochrome P-45011 beta was also reflected in a relatively high level of 11 beta-hydroxylase activity measured in a homogenate of this brain area by biochemical enzymatic assays using [4-14C]-11-deoxycorticosterone.(ABSTRACT TRUNCATED AT 250 WORDS)
Ozaki
H S
HS
Department of Anatomy, Kagawa Medical School, Japan.
Iwahashi
K
K
Tsubaki
M
M
Fukui
Y
Y
Ichikawa
Y
Y
Takeuchi
Y
Y
D000302:Adrenal Cortex / Q000201:enzymology / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000201:enzymology*; D002417:Cattle; D003345:Corticosterone / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D007150:Immunohistochemistry; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D013252:Steroid 11-beta-Hydroxylase / Q000276:immunology / Q000378:metabolism*
D013252:Steroid 11-beta-Hydroxylase; D003345:Corticosterone