Myoinhibitory peptides in the brain of the cockroach Leucophaea maderae and colocalization with pigment‐dispersing factor in circadian pacemaker cells

Abstract

Myoinhibitory peptides (MIPs) are a family of insect W(X(6))Wamides with inhibitory effects on visceral muscles and juvenile hormone synthesis. Although MIPs are widely distributed within the nervous system, a detailed analysis of their distribution and function in insect brains is still missing. We analyzed the distribution of MIPs in the brain of the cockroach Leucophaea maderae. We focused on the accessory medulla (AMe), a small neuropil near the medulla that acts as the master circadian clock. Matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) and Nano-LC electrospray ionization (ESI) mass spectrometry revealed five Lem-MIPs in preparations of the AMe and corpora cardiaca. The complete sequences of two of these peptides were identified. Immunocytochemistry revealed wide distribution of MIP-related peptides in the cockroach brain. The superior median protocerebrum, parts of the central complex, and the tritocerebrum showed particularly dense immunostaining. In contrast, only a few local interneurons were stained in the antennal lobe and a few extrinsic neurons in the mushroom body, including a giant neuron innervating the calyces. The noduli of the AMe showed dense immunostaining, and neurons in all AMe cell groups except the anterior neurons were labeled. Pigment-dispersing factor- (PDF) and MIP immunostaining was colocalized in two neurons of the AMe. No colocalization of MIP- and PDF immunostaining was detected in the anterior optic commissure, but two small PDF-immunoreactive commissural fibers near the posterior optic commissure showed colocalized MIP immunostaining. The results suggest that several MIPs participate in different functional circuits of the circadian system and are involved in multiple brain circuits of the Madeira cockroach.

The Distribution and Physiological Effects of the Myoinhibiting Peptides in the Kissing Bug, Rhodnius Prolixus

“…In comparison with L. migratoria , M. sexta , or B. mori , the CNS of R. prolixus has a much larger number of MIP-like immunoreactive neurons, indicating that MIPs might play important central roles as neurotransmitters/neuromodulators in R. prolixus . Such has also been proposed for the cockroach L. maderae , where ∼2,000 cells have been described (Schulze et al, 2012). Indeed, in this cockroach, there is a very wide distribution of MIP-like immunoreactive neurons in the brain, including co-localization with circadian pacemaker cells containing pigment-dispersing factor, leading the authors to suggest that MIPs may be involved in the circadian system, in the processing of chemosensory information and also in the coordination of feeding and locomotory centers (Schulze et al, 2012).…”

“…Such has also been proposed for the cockroach L. maderae , where ∼2,000 cells have been described (Schulze et al, 2012). Indeed, in this cockroach, there is a very wide distribution of MIP-like immunoreactive neurons in the brain, including co-localization with circadian pacemaker cells containing pigment-dispersing factor, leading the authors to suggest that MIPs may be involved in the circadian system, in the processing of chemosensory information and also in the coordination of feeding and locomotory centers (Schulze et al, 2012). Similarly, in R. prolixus one might speculate that the wide distribution of MIP-like immunoreactive neurons in the various regions of the brain suggests an involvement of MIPs in at least visual processing, and also the olfactory system.…”

“…Some MIPs have been designated as allatostatin-Bs (AST-Bs) because they inhibit juvenile hormone production in the corpora allata of G. bimaculatus (Lorenz et al, 1995) or as prothoracicostatic peptides (PTSPs) because they suppress ecdysteroid genesis in the prothoracic glands of B. mori (Hua et al, 1999; Yamanaka et al, 2010). Centrally, MIPs appear to play a role in the abdominal circuits associated with ecdysis behavior in M. sexta and D. melanogaster (Davis et al, 2003; Kim et al, 2006a,b; Santos et al, 2007), and in Leucophaea maderae in multiple brain circuits, including the circadian system (Schulze et al, 2012). …”

Myotropic activity and immunolocalization of selected neuropeptides of the burying beetle Nicrophorus vespilloides (Coleoptera: Silphidae)

“…The MIP‐immunoreactive cells in the nervous system and other tissues of many insect species have been identified (Blackburn et al ., ; Predel et al ., ; Li et al ., ; Lange et al ., ; Schulze et al ., ). However, in case of Coleoptera, research has only been conducted concerning the presence of MIPs in the brain of beetles (mass spectrometry analysis) or the localization in mushroom bodies (Weaver & Audsley, ; Marciniak et al ., ; Heuer et al ., ).…”

Myoinhibitory peptide regulates feeding in the marine annelidPlatynereis

“…Many neuropeptides are known to have roles in regulating different aspects of feeding [26][27][28]. MIPs/Wamides are also pleiotropic [29][30][31][32][33][34][35] and regulate aspects of feeding and gut muscle activity in some insects and cnidarians. The first MIP described had a myoinhibitory function on adult locust hindgut [36].…”