The neuropeptide SIFamide in the brain of three cockroach species

• Published in: Journal of comparative neurology (1911) Vol. 524; no. 7; pp. 1337 - 1360
• Main Authors: Arendt, Andreas, Neupert, Susanne, Schendzielorz, Julia, Predel, Reinhard, Stengl, Monika
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.05.2016; Wiley Subscription Services, Inc
• Subjects: AB_177540; AB_2314344; AB_2314455; AB_760350; Animals; Blaberidae; Blattidae; Brain - drug effects; Brain - metabolism; Circadian Rhythm - drug effects; Circadian Rhythm - physiology; cockroach; Cockroaches - anatomy & histology; Cockroaches - physiology; Dose-Response Relationship, Drug; Drosophila; GABA; gamma-Aminobutyric Acid - metabolism; Ganglia, Invertebrate - metabolism; histamine; Histamine - metabolism; insect brain; Insect Proteins - metabolism; Insect Proteins - pharmacology; Leucophaea maderae; Motor Activity - drug effects; Motor Activity - physiology; neuropeptides; Neuropeptides - metabolism; Neuropeptides - pharmacology; Periplaneta americana; Polyphagidae; Rhyparobia; Rhyparobia maderae; SIFamide; Species Specificity; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Statistics, Nonparametric; AB_2314455; AB_177540; AB_2314344; histamine; insect brain; cockroach; GABA; neuropeptides; SIFamide; AB_760350
• ISSN: 0021-9967; 1096-9861
• DOI: 10.1002/cne.23910

ABSTRACT The sequence as well as the distribution pattern of SIFamide in the brain of different insects is highly conserved. As a general rule, at least four prominent SIFamide‐immunoreactive somata occur in the pars intercerebralis. They arborize throughout the brain and the ventral nerve cord. Whereas SIFamide is implicated in mating and sleep regulation in Drosophila, other functions of this peptide remain largely unknown. To determine whether SIFamide plays a role in the circadian system of cockroaches, we studied SIFamide in Rhyparobia (= Leucophaea) maderae (Blaberidae), Periplaneta americana (Blattidae), and Therea petiveriana (Polyphagidae). Matrix‐assisted laser desorption/ionization–time of flight (MALDI–TOF) mass spectrometry revealed identical SIFamide sequences (TYRKPPFNGSIFamide) in the three species. In addition to four large immunoreactive cells in the pars intercerebralis (group 1), smaller SIFamide‐immunoreactive somata were detected in the pars intercerebralis (group 2), in the superior median protocerebrum (group 3), and in the lateral protocerebrum (group 4). Additional cells in the optic lobe (group 5) and posterior protocerebrum (group 6) were stained only in P. americana. Almost the entire protocerebrum was filled with a beaded network of SIFamide‐immunoreactive processes that especially strongly invaded the upper unit of the central body. Double‐label experiments did not confirm colocalizations with γ‐aminobutyric acid (GABA) or the circadian coupling peptide pigment‐dispersing factor (PDF). In contrast to locusts, colocalization of SIFamide and histamine immunoreactivity occurred not in group 1, but in group 4 cells. Because the accessory medulla displayed SIFamide immunoreactivity and injections of SIFamide delayed locomotor activity rhythms circadian time‐dependently, SIFamide plays a role in the circadian system of cockroaches. J. Comp. Neurol. 524:1337–1360, 2016. © 2015 Wiley Periodicals, Inc. Using immunostaining, the authors demonstrated that SIFamide is expressed in four highly conserved large pars intercerebralis cells (1) in the cockroaches Periplaneta americana, Rhyparobia maderae, and Therea petiveriana, but also occurred in additional cell groups. Most were found in P. americana, which expressed SIFamide in six different cell clusters. CA, calyx; LO, lobula; ME, medulla; ML, medial lobe; PED, peduncle; LO, lobula; VL, vertical lobe. Scale bar = 100 μm in top panel; 100 μm in bottom panel.