Circadian Rhythmicity of Vasopressin Levels in the Cerebrospinal Fluid of Suprachiasmatic Nucleus-Lesioned and Grafted Rats

Abstract

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.

Technologies of sleep research

“…Cannulas enable the delivery of relative large quantities of liquid and soluble substances and have been used for a wide range of brain areas and substances in the last 30 years. Another possibility with cannulas is the retrieval of cerebrospinal fluid (CSF) [ 8 , 51 , 52 ]. This technique is less common, but may be an alternative to microdialysis when larger amounts of fluid are needed or when a comparable situation to human CSF analysis is preferred.…”

Suprachiasmatic vasopressin and the circadian regulation of voluntary locomotor behavior

“…However, the suprachiasmatic nucleus (SCN) presents a unique site as the location of a central biological clock controlling locomotor behavior and physiology (Moore & Eichler, ; Stephan & Zucker, ; Ralph et al ., ). It also is the source of rhythmic AVP in the hypothalamus and cerebrospinal fluid (Schwartz & Reppert, ; Kalsbeek et al ., ; Kalsbeek & Buijs, ; Van Esseveldt et al ., ) and in vitro (Earnest & Sladek, , ; Gillette & Reppert, ; Murakami et al ., ; Watanabe et al ., ; Shinohara et al ., ; Gerkema et al ., ; Jansen et al ., ; Van der Zee et al ., ).…”