Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 100, Issue 7, Pages 4269-4274Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0730816100
Keywords
-
Categories
Funding
- NEI NIH HHS [EY01682, R01 EY001682] Funding Source: Medline
- NIDA NIH HHS [DA09374, R01 DA009374] Funding Source: Medline
- NIDDK NIH HHS [R01DK33301, R01 DK033301] Funding Source: Medline
Ask authors/readers for more resources
On the basis of temperature dependency, saturability, selective inhibition, and substrate specificity, it has been proposed that an anandamide transporter exists. However, all of these studies have examined anandamide accumulation at long time points when downstream effects such as metabolism and intracellular sequestration are operative. In the current study, we have investigated the initial rates (<1 min) of anandamide accumulation in neuroblastoma and astrocytoma cells in culture and have determined that uptake is not saturable with increasing concentrations of anandamide. However, anandamide hydrolysis, after uptake in neuroblastoma cells, was saturable at steady-state time points (5 min), suggesting that fatty acid amide hydrolase (FAAH) may be responsible for observed saturation of uptake at long time points. In general, arvanil, olvanil, and N-(4-hydroxyphenyl)arachidonylamide (AM404) have been characterized as transport inhibitors in studies using long incubations. However, we found these transport inhibitors did not inhibit anandamide uptake in neuroblastoma and astrocytoma cells at short time points (40 sec or less). Furthermore, we confirmed that these inhibitors in vitro were actually inhibitors of FAAH. Therefore, the likely mechanism by which the transport inhibitors raise anandamide levels to exert pharmacological effects is by inhibiting FAAH, and they should be reevaluated in this context. Immunofluorescence has indicated that FAAH staining resides mainly on intracellular membranes of neuroblastoma cells, and this finding is consistent with our observed kinetics of anandamide hydrolysis. In summary, these data suggest that anandamide uptake is a process of simple diffusion. This process is driven by metabolism and other downstream events, rather than by a specific membrane-associated anandamide carrier.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available