Journal of Neuroscience, Vol 15, 470-476, Copyright © 1995 by Society for Neuroscience
Neuronal and glial prostaglandin D synthase isozymes in chick dorsal root ganglia: a light and electron microscopic immunocytochemical study
MF Vesin, Y Urade, O Hayaishi and B Droz
Institut d'Histologie et d'Embryologie, Faculte de Medecine, Universite de Lausanne, Switzerland.
Homogenates of chick dorsal root ganglia (DRG) and in vitro cultures of DRG
neurons are known to synthesize prostaglandin (PG) D2. To specify the PGD
synthase isozymes controlling PGD2 synthesis in DRG and to identify the DRG
cells responsible for this synthesis, we applied polyclonal antibodies
raised against rat brain or rat spleen PGD synthase isozymes to vibratome
or cryostat slices of DRG previously fixed with a
formaldehyde-lysine-periodate mixture and permeabilized with Triton X-100.
The immunoreactivity indicating rat spleen PGD synthase, a glutathione
(GSH)-requiring enzyme, was located in satellite cells encompassing
particular large neurons of class A and in Schwann cells myelinating and
enwrapping their initial axonal segments. In contrast, the immunoreactivity
of rat brain PGD synthase, a GSH- independent enzyme, was restricted to
particular ganglion cell perikarya: 33% of the DRG neurons were
immunostained for rat brain PGD synthase, including 2% of large class A
neurons and 40% of small class B neurons. Only 3.3% of rat brain PGD
synthase-immunoreactive small B neurons coexpressed substance P, indicating
that the immunoreactive neurons belong to the B1 subclass. By electron
microscopy, 71 of 72 immunoreactive DRG cells were identified as small B
neurons of the B1 subclass, and 71 of 77 B1 neurons were immunoreactive for
rat brain PGD synthase. These results demonstrate that PGD2 formation in
DRG is regulated by two isozymes: the GSH-requiring isozyme located in
satellite and Schwann cells and the GSH-independent isozyme-confined to
small B1 neurons.