S. Yazulla et al., Immunocytochemical localization of cannabinoid CB1 receptor and fatty acidamide hydrolase in rat retina, J COMP NEUR, 415(1), 1999, pp. 80-90
Cannabinoids have major effects on central nervous system function. Recent
studies indicate that cannabinoid effects on the visual system have a retin
al component. Immunocytochemical methods were used to localize cannabinoid
CB1 receptor immunoreactivity (CB1R-IR) and an endocannabinoid (anandamide
and 2-arachidonylglycerol) degradative enzyme, fatty acid amide hydrolase (
FAAH)-IR, in the rat retina. Double labeling with neuron-specific markers p
ermitted identification of cells that were labeled with CB1R-IR and FAAH-IR
. CB1R-IR was observed in all cells that were protein kinase C-immunoreacti
ve (rod bipolar cells and a subtype of GABA-amacrine cell) as well as horiz
ontal cells (identified by calbindin-IR). There was also punctate CB1R-IR i
n the distal one-third of the inner plexiform layer (IPL) that could not be
assigned to a cell type. FAAH-IR was most prominent in large ganglion cell
s, whose dendrites projected to a narrow band in the proximal IPL. Weaker F
AAH-IR was observed in the soma of horizontal cells (identified by calbindi
n-IR); the soma of large, but not small, dopamine amacrine cells (identifie
d by tyrosine hydroxylase-IR); and dendrites of orthotopic- and displaced-s
tarburst amacrine cells (identified by choline acetyltransferase-IR) but in
less than 50% of the starburst amacrine cell somata. The extensive distrib
ution of CB1R-IR on horizontal cells and rod bipolar cells indicates a role
of endocannabinoids in scotopic vision, whereas the more widespread distri
bution of FAAH-IR indicates a complex control of endocannabinoid release an
d degradation in the retina. (C) 1999 Wiley-Liss. Inc.