IMMUNOCYTOCHEMICAL AND IN-VITRO AUTORADIOGRAPHIC EVIDENCE FOR A DIRECT SOMATOSTATINERGIC MODULATION OF THE ENKEPHALINERGIC HYPOTHALAMOSEPTAL TRACT OF THE GUINEA-PIG
A. Pillez et al., IMMUNOCYTOCHEMICAL AND IN-VITRO AUTORADIOGRAPHIC EVIDENCE FOR A DIRECT SOMATOSTATINERGIC MODULATION OF THE ENKEPHALINERGIC HYPOTHALAMOSEPTAL TRACT OF THE GUINEA-PIG, Neuroscience, 58(1), 1994, pp. 207-215
The present study was undertaken to determine whether the enkephaliner
gic hypothalamoseptal tract originating in the magnocellular dorsal nu
cleus in the guinea-pig brain is under the influence of somatostatin.
In the first step, double immunocytochemical labeling of enkephalinerg
ic cells and somatostatinergic fibers was combined at the light and el
ectron microscopic levels in the magnocellular dorsal nucleus. As a se
cond step, an in vitro radioautography was used to determine whether s
omatostatin receptors are present in the same area. A close relationsh
ip between somatostatin nerve endings and enkephalin perikarya was obs
erved at both the light and electron microscopic levels. Contacts were
more numerous in the ventral part of the magnocellular dorsal nucleus
. Whenever synaptic images were clearly observable; they appeared symm
etrical. In the same area, a moderate concentration of G-protein-coupl
ed somatostatin binding sites was also visualized. These results sugge
st that somatostatin has a regulator role on the enkephalinergic hypot
halamoseptal tract, directly at the level of the magnocellular dorsal
nucleus.