Mj. Wayner et al., LATERAL HYPOTHALAMIC-STIMULATION INHIBITS DENTATE GRANULE CELL LTP - DIRECT CONNECTIONS, Brain research bulletin, 43(1), 1997, pp. 5-15
We discovered that angiotensin II (Ang II) applied directly to the den
tate gyrus inhibited LTP induction in medial perforant path-dentate gr
anule cell synapses and that the inhibition can be blocked by losartan
, an Ang II AT(1) receptor specific antagonist. In the first part of t
his study we found that electrical stimulation of the lateral hypothal
amus (LH) inhibits LTP in these synapses and the inhibition can be blo
cked by pretreating the animals with losartan, indicating that LH angi
otensin-containing neurons project to the dentate gyrus. Results of th
e second part of the study demonstrate clearly that some angiotensin-c
ontaining LH neurons project directly to dentate granule cells. LH neu
rons were identified by retrograde tracers applied to the granule cell
layer. Double-labeled neurons containing angiotensin and HRP were spa
rsely distributed and both fusiform and multipolar LH neurons appeared
in a smart cluster lateral and ventral to the fornix at the level of
the paraventricular nucleus. Large numbers of angiotensin staining neu
rons were observed in the hypothalamus. Results support our hypothesis
that some angiotensin containing LH neurons project directly to the d
entate gyrus. (C) 1997 Elsevier Science Inc.