Sex Hormone-Dependent Regulation of MCT1 on the Blood Brain Barrier
Poster Number
2C
Introduction/Abstract
Proton-dependent monocarboxylate transporters (MCTs) are involved in monocarboxylate uptake and efflux in a range of biologically important tissues and barriers, including the liver, kidney, and blood-brain barrier (BBB) (1). MCTs are involved in the transport of L-lactate and monocarboxylate drugs, including gamma-hydroxybutyrate, valproic acid, gabapentin enacarbil, non-steroidal anti-inflammatories, and β-lactam antibiotics (1). Among all the isoforms, MCT1 is localized ubiquitously in the body, which is essential for drug absorption, distribution, and elimination. Moreover, MCT1 can be found on the BBB, which is critical for brain distribution; increased BBB MCT1 may increase drug distribution to the brain (2). In our laboratory, we have published data demonstrating sex hormone-dependent regulation of hepatic MCT1, MCT4, SMCT1, and CD147 (3). These data support sex hormone-dependent regulation of the underlying physiological processes governing the distribution and clearance of MCT substrates.
Purpose
The purpose of this project is to validate the BBB isolation technique and characterize MCT1 membrane protein expression localized on the BBB in animals treated with sex and cross-sex hormone therapy.
Method
Male and female Sprague Dawley (SD) rats, ovariectomized (OVX) females, and castrated (CST) males were obtained from Charles River at 8 weeks of age and were housed in a temperature-controlled room with a 12-hour day/night lighting cycle. At 10 weeks of age, OVX female and CST male SD rats were implanted subcutaneously with 60-day release pellets containing 1.5 mg estrogen and/or 50 mg progesterone or their corresponding control pellets (Innovative Research of America) (N = 6/treatment group). The BBB isolation technique was performed using a protocol developed by the University of Arizona (4). Following euthanasia, brains were harvested. Cerebral hemispheres were isolated and homogenized with brain microvessel buffer. After 4 dextran centrifugation steps, pellets enriched with BBB were obtained. Membrane bound protein was extracted from BBB pellets using a ProteoExtract Native Membrane Extraction kit. Na+/K+ ATPase expression was evaluated by western blot to verify membrane isolation. BBB purity was assessed by western blot against platelet endothelial cell adhesion molecule-1 (PECAM-1) and synaptophysin. MCT1 protein expression levels were quantified by western blot and normalized to Na+/K+ ATPase expression.
Results
The purity of each BBB sample was validated by western blots against PECAM-1 and synaptophysin. No significant difference in MCT1 protein expression levels was found between hormone implanted and their corresponding placebo groups for both OVX and CST animals. OVX implanted with female sex hormone exhibited lower MCT1 expression than their corresponding placebo groups. CST males implanted with estrogen/progesterone showed significantly lower MCT1 expression compared to CST males implanted with progesterone alone.
Significance
Results from this project will advance our fundamental knowledge of the sex hormone regulation of drug transporters. Understanding the gender-specific drug transporter variation is particularly important for designing safe and effective treatments. Characterization of these regulatory pathways has broad-based application in other clinical research areas where monocarboxylate transporters have been identified as putative therapeutic targets.
Location
William Knox Holt Memorial Library and Learning Center, University of the Pacific, 3601 Pacific Ave., Stockton, CA 95211
Format
Poster Presentation
Poster Session
Afternoon
Sex Hormone-Dependent Regulation of MCT1 on the Blood Brain Barrier
William Knox Holt Memorial Library and Learning Center, University of the Pacific, 3601 Pacific Ave., Stockton, CA 95211
Proton-dependent monocarboxylate transporters (MCTs) are involved in monocarboxylate uptake and efflux in a range of biologically important tissues and barriers, including the liver, kidney, and blood-brain barrier (BBB) (1). MCTs are involved in the transport of L-lactate and monocarboxylate drugs, including gamma-hydroxybutyrate, valproic acid, gabapentin enacarbil, non-steroidal anti-inflammatories, and β-lactam antibiotics (1). Among all the isoforms, MCT1 is localized ubiquitously in the body, which is essential for drug absorption, distribution, and elimination. Moreover, MCT1 can be found on the BBB, which is critical for brain distribution; increased BBB MCT1 may increase drug distribution to the brain (2). In our laboratory, we have published data demonstrating sex hormone-dependent regulation of hepatic MCT1, MCT4, SMCT1, and CD147 (3). These data support sex hormone-dependent regulation of the underlying physiological processes governing the distribution and clearance of MCT substrates.
