Circadian rhythmicity of vasopressin levels in the cerebrospinal fluid of suprachiasmatic nucleus-lesioned and -grafted rats.
Transplantation of the fetal suprachiasmatic nucleus (SCN) in arrhythmic SCN-lesioned rats can reinstate circadian drinking rhythms in 40% to 50% of the cases. In the current article, it was investigated whether the failure in the other rats could be due to the absence of a circadian rhythm in the grafted SCN, using a circadian vasopressin (VP) rhythm in the cerebrospinal fluid (CSF) as the indicator for a rhythmic SCN. CSF was sampled in continuous darkness from-intact control rats and SCN-lesioned and -grafted rats. VP could be detected in all samples, with concentrations of 15 to 30 pg/ml in the control rats and 5 to 15 pg/ml in the grafted rats. A circadian VP rhythm with a two- to threefold difference between peak and nadir values was found in all 7 control rats but in only 4 of 13 experimental rats, despite the presence of a VP-positive SCN in all grafts. A circadian VP rhythm was present in 2 drinking rhythm-recovered rats (6 of 13) and in 2 nonrecovery rats. Apparently, in these latter rats, the failure of the grafted SCN to restore a circadian drinking rhythm cannot be attributed to a lack of rhythmicity in the SCN itself. Thus, the presence of a rhythmic grafted SCN, as is deduced from a circadian CSF VP rhythm, appears not to be sufficient for restoration of a circadian drinking rhythm in SCN-lesioned arrhythmic rats.
Graduate School Neurosciences Amsterdam, Netherlands Institute for Brain Research.
K E
KE
van Esseveldt
B A
BA
van der Geest
H
H
Duindam
W J
WJ
Rietveld
G J
GJ
Boer
D000818:Animals; D002940:Circadian Rhythm; D004327:Drinking Behavior; D007150:Immunohistochemistry; D008297:Male; D009412:Nerve Fibers / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D020127:Recovery of Function; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000502:physiology* / Q000601:surgery / Q000637:transplantation; D013997:Time Factors; D014667:Vasopressins / Q000134:cerebrospinal fluid* / Q000378:metabolism
D014667:Vasopressins