Effects of hypocretin-1 in 192-IgG-saporin-lesioned rats.
Hypocretin, also known as orexin, is a neuropeptide located in the perifornical region of the lateral hypothalamus; this region projects to all the major arousal centres including the basal forebrain. The basal forebrain contains a mixed population of neurons, some of which are cholinergic. To identify the relative contribution of the noncholinergic neurons to arousal, here we utilized 192-IgG-saporin to lesion the basal forebrain cholinergic neurons and determine whether microinjection of hypocretin-1 to the basal forebrain is still effective in inducing arousal. In Sprague-Dawley rats given 192-IgG-saporin (intraventricular, 6 microg; n=7) 92% of the basal forebrain cholinergic neurons were destroyed compared to nonlesioned rats (n=5). In the lesioned rats microinjection of hypocretin-1 (0.0625, 0.125 or 0.25 nmol in 250 nL) to the basal forebrain increased waking and suppressed sleep (both non-REM and REM) in a concentration-dependent manner and to the same extent as in nonlesioned rats. These results suggest that, in the absence of the basal forebrain cholinergic neurons, the basal forebrain noncholinergic neurons are able to convey hypocretin's arousal signal unabated.
Blanco-Centurion
Carlos A
CA
Department of Neurology, West Roxbury VA Medical Center and Harvard Medical School, 1400 VFW Parkway, West Roxbury, MA 02132, USA.
Shiromani
Anjelica
A
Winston
Elizabeth
E
Shiromani
Priyattam J
PJ
D000704:Analysis of Variance; D000818:Animals; D000911:Antibodies, Monoclonal; D001930:Brain Injuries / Q000139:chemically induced* / Q000378:metabolism* / Q000503:physiopathology; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D007150:Immunohistochemistry / Q000379:methods; D000922:Immunotoxins; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D009699:N-Glycosyl Hydrolases; D009479:Neuropeptides / Q000378:metabolism* / Q000494:pharmacology; D000068797:Orexins; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D054789:Ribosome Inactivating Proteins, Type 1; D000076985:Saporins; D012890:Sleep / Q000187:drug effects / Q000502:physiology; D016138:Walking / Q000502:physiology
C085696:192 IgG-saporin; D000911:Antibodies, Monoclonal; D000922:Immunotoxins; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D054789:Ribosome Inactivating Proteins, Type 1; D002795:Choline O-Acetyltransferase; D009699:N-Glycosyl Hydrolases; D000076985:Saporins