17 Beta-estradiol suppresses AMPA-induced increases in regional cerebral O2 consumption.
We tested the hypothesis that 17 beta-estradiol would reduce the cerebral O2 consumption response resulting from glutamate receptor stimulation by alpha amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA). Fourteen ovariectomized rats were separated into 17 beta-estradiol (0.5 mg 21 day release pellet) and control (placebo pellet) groups to determine cerebral blood flow (14C-iodoantipyrine) and O2 consumption (microspectrophotometry). After topical cortical stimulation with 10(-3) M and 10(-4) M AMPA, cerebral blood flow increased significantly in both groups in a concentration-dependent manner. Cerebral O2 extraction was not significantly different in any region of the 17 beta-estradiol treated group. In the placebo treated group, the O2 extraction in the saline treated cortex and in the 10(-3) M AMPA treated cortex was significantly higher when compared to the 10(-4) M AMPA treated cortex. Cerebral O2 consumption in the control group increased by 20%, from 5.2 +/- 0.6 to 6.1 +/- 0.7, with 10(-4) M AMPA and significantly increased by 64% to 8.5 +/- 0.8 ml O2 min-1 100 g-1 with 10(-3) M AMPA. The 17 beta-estradiol group demonstrated no statistically significant difference in O2 consumption between the saline treated and AMPA treated cortex. Thus, 17 beta-estradiol reduced the effects of AMPA in increasing cerebral O2 consumption.
Heart and Brain Circulation Laboratory, Department of Physiology and Biophysics and Anesthesia, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, 125 Paterson Street, Suite 3100, New Brunswick, NJ 08901-1977, USA.
Yakir K
YK
Vaks
Harvey R
HR
Weiss
Xia
X
Liu
Oak Z
OZ
Chi
D000818:Animals; D002540:Cerebral Cortex / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D010052:Ovariectomy; D010101:Oxygen Consumption / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology*
D004958:Estradiol; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid