Lateral hypothalamic stimulation inhibits dentate granule cell LTP: direct connections.
We discovered that angiotensin II (Ang II) applied directly to the dentate gyrus inhibited LTP induction in medial perforant path-dentate granule cell synapses and that the inhibition can be blocked by losartan, an Ang II AT1 receptor specific antagonist. In the first part of this study we found that electrical stimulation of the lateral hypothalamus (LH) inhibits LTP in these synapses and the inhibition can be blocked by pretreating the animals with losartan, indicating that LH angiotensin-containing neurons project to the dentate gyrus. Results of the second part of the study demonstrate clearly that some angiotensin-containing LH neurons project directly to dentate granule cells. LH neurons were identified by retrograde tracers applied to the granule cell layer. Double-labeled neurons containing angiotensin and HRP were sparsely distributed and both fusiform and multipolar LH neurons appeared in a small cluster lateral and ventral to the fornix at the level of the paraventricular nucleus. Large numbers of angiotensin staining neurons were observed in the hypothalamus. Results support our hypothesis that some angiotensin containing LH neurons project directly to the dentate gyrus.
Wayner
M J
MJ
Division of Life Sciences, University of Texas at San Antonio 78249-0662, USA.
Phelix
C F
CF
Armstrong
D L
DL
D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology*; D018891:Dentate Gyrus / Q000166:cytology / Q000187:drug effects*; D004353:Drug Evaluation, Preclinical; D004558:Electric Stimulation; D007026:Hypothalamic Area, Lateral / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology*; D017774:Long-Term Potentiation / Q000187:drug effects*; D019808:Losartan; D008297:Male; D009434:Neural Pathways / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013777:Tetrazoles / Q000494:pharmacology*
D057911:Angiotensin Receptor Antagonists; D001713:Biphenyl Compounds; D007093:Imidazoles; D013777:Tetrazoles; D019808:Losartan