Drosophila DH31 neuropeptide and PDF receptor regulate night-onset temperature preference

Abstract

Body temperature exhibits rhythmic fluctuations over a 24 h period (Refinetti and Menaker,1992) and decreases during the night,which is associated with sleep initiation (Gilbert et al.,2004; Kräuchi,2007a,b). However,the underlying mechanism of this temperature decrease is largely unknown. We have previously shown that Drosophila exhibit a daily temperature preference rhythm (TPR),in which their preferred temperatures increase during the daytime and then decrease at the transition from day to night (night-onset) (Kaneko et al.,2012). Because Drosophila are small ectotherms,their body temperature is very close to that of the ambient temperature (Stevenson,1985),suggestingthat their TPRgeneratestheir bodytemperaturerhythm. Here,wedemonstratethat theneuropeptidediuretichormone 31 (DH31) and pigment-dispersing factor receptor (PDFR) contribute to regulate the preferred temperature decrease at night-onset. We show that PDFR and tethered-DH31 expression in dorsal neurons 2 (DN2s) restore the preferred temperature decrease at night-onset,suggesting that DH31 acts on PDFR in DN2s. Notably,we previously showed that the molecular clock in DN2s is important for TPR. Although PDF (another ligand of PDFR) is a critical factor for locomotor activity rhythms,Pdf mutants exhibit normal preferred temperature decreases at night-onset. This suggests that DH31-PDFR signaling specifically regulates a preferred temperature decrease at night-onset. Thus,we propose that night-onset TPR and locomotor activity rhythms are differentially controlled not only by clock neurons but also by neuropeptide signaling in the brain.