The distribution and physiological functions of DH44 and DH31 neurons and their receptors in adult Drosophila. A schematic summary is presented to depict the anatomical distribution and diverse biological functions of DH44 and DH31 signaling in adult Drosophila. DH44 + PI neurons secrete the DH44 peptide to neurons expressing DH44-R1, which increases food intake. They also secrete DH44 peptide to the midgut to activate gut motility and to the Malpighian tubules to stimulate body fluid secretion. DH31-producing enteroendocrine cells located in the posterior midgut secrete the DH31 peptide to DN1 neurons in the brain, which play a role in regulating sleep/circadian behavior. These cells also regulate gut contraction via the DH31-R expressed on the midgut. In addition, a sleep and circadian rhythm-regulating peptide PDF activate DH31-expressing neurons, further regulating sleep and circadian behavior in the adult brain. DH44 + PI, diuretic hormone 44 expressing neurons located in the pars intercerebralis of the brain; DH31, diuretic hormone 31 expressing cells; DH44-R1, diuretic hormone 44 receptor 1 expressing neurons; DH44-R2, diuretic hormone 44 receptor 2 expressing cells; DH31, diuretic hormone 31 expressing cell; DH31-R, diuretic hormone 31 receptor-expressing cells; CRZ, corazonin; PDF, pigment dispersing factor; DN1, dorsal neuron 1; PV, proventriculus; CC, corpora cardiaca; HCG, hypocerebral ganglion; VNC, ventral nerve cord.
