Abstract
Little is known about the function of oxytocin (OT) in males. We have recently observed a diurnal rhythm of OT levels in adult male monkey CSF. In the present study we determined whether altered lighting patterns would affect this rhythm.
Four male rhesus monkeys (5.5-6.5 kg) were adapted to chronic restraint primate chairs. Polyethylene catheters were threaded via a spinal needle from the lumbosacral area cephalad in the subarachnoid space. CSF was withdrawn continuously by peristatic pump at a rate of 1 ml/hr and collected as 2 hr samples. OT was measured in CSF by radioimmunoassay without extraction. Recovery of added OT in pooled monkey CSF was 73-89%. As expected, there was a 3-7 fold increase in CSF OT concentrations during the day relative to nighttime values. In monkeys kept in light/dark of 12 hr/12 hr, nighttime OT concentrations ranged from 2-10 μU/ml; daytime concentrations ranged from 7-60 μU/ml. This pattern persisted despite constant light or dark for 72 hrs with no significant change in the rhythm or its relationship to time of day.
These results suggested that the CSF OT rhythm is endogenously generated. Perlow et al have shown that blood levels of OT in rhesus monkeys show no rhythmic pattern. The organized rhythm of OT confined to the CSF suggests that OT may have a separate function in the nervous system as a neuroendocrine transmitter.
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Artnian, H., Reppert, S., Perlow, M. et al. 382 OXYTOCIN RHYTHM IN PRIMATE CSF. Pediatr Res 15 (Suppl 4), 503 (1981). https://doi.org/10.1203/00006450-198104001-00393
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DOI: https://doi.org/10.1203/00006450-198104001-00393