Neurosecretory cells: daily rhythmicity in Leiobunum longipes.
A fluorometric-analysis procedure, used to quantitate indoles, confirmed the presence of 5-hydroxytryptamine (5-HT) in an arachnid; there was unimodal cyclic production of 5-HT in brain and intestinal tissues over a 24-hour period. The same tissues produced 5-HT after 80-day culture; bimodal cyclic output was indicated during continuous 24-hour study. One peak occurred at 0200 hours, at the same time as the peak in vivo, suggesting an endogenously controlled mechanism of secretion. The second peak occurred at midmorning, a time when production in vivo was lowest, suggesting that there is a possible feedback-control mechanism in the organism that inhibits the endogenous output of 5-HT.
D000818:Animals; D001097:Arachnida / Q000502:physiology*; D001921:Brain / Q000378:metabolism; D002940:Circadian Rhythm; D005246:Feedback; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism; D009489:Neurosecretion / Q000502:physiology*; D012701:Serotonin / Q000096:biosynthesis*
D012701:Serotonin