Immunocytochemical demonstration of locustatachykinin‐related peptides in the central complex of the locust brain

Abstract

The central complex, a highly ordered neuropil area in the insect brain, plays a role in motor control and spatial orientation. To further elucidate the neurochemical architecture of this brain area, we have investigated the distribution and morphology of neurons containing locustatachykinin I/II-related substances in the central complex of the locust Schistocerca gregaria. The central complex is innervated by at least 66 locustatachykinin I/II-immunoreactive neurons, which belong to two sets of tangential neurons and four sets of columnar neurons. These neurons give rise to immunostaining in the protocerebral bridge, in several layers of the upper division of the central body, and in all layers except layer 5 of the lower division of the central body. Double-label experiments show colocalization of immunoreactivity for both locustatachykinin I/II and octopamine in tangential neurons of the protocerebral bridge. A pair of tangential neurons of the lower division of the central body exhibits both locustatachykinin I/II and gamma-aminobutyric acid (GABA) immunoreactivity. A set of 16 columnar neurons of the lower division of the central body shows colocalized immunoreactivity for locustatachykinin II, leucokinin, and substance P. This study reveals novel features of the anatomical organization of the locust central complex and suggests a prominent role for locustatachykinin-related peptides as neuromediators and cotransmitters within this brain area.

Polarization-Sensitive Descending Neurons in the Locust: Connecting the Brain to Thoracic Ganglia

“…The anti-locustatachykinin II (Lom-TK II) antiserum (K1-50820091) was donated by Dr. Hans Agricola (University of Jena, Jena, Germany) and was used at a dilution of 1:30,000. Its specificity on S. gregaria brain sections has been characterized by Vitzthum and Homberg (1998). For staining of neurons containing A-type allatostatins (AST-A), an antiserum against Diploptera punctata allatostatin 7 was used.…”

NO/cGMP signalling: L-citrulline and cGMP immunostaining in the central complex of the desert locust Schistocerca gregaria

“…4a) has a morphology similar to the locustatachykinin-immunoreactive columnar neurons of the central body, type IV, stained with antisera against Locusta migratoria tachykinin II (Vitzthum and Homberg 1998). Arborizations were found in layers I and IIa of the CBU and in the anterior dorsal shell of the LAL, but primary neurites and cell bodies could not be identified.…”

Neuropeptides in theDrosophilacentral complex in modulation of locomotor behavior

“…TK immunostaining of the central complex in various other insect species also shows obvious diversity in neuron types. For instance, in the locust four different populations of columnar fb neurons and two different populations of tangential neurons have been identified (Vitzthum and Homberg, 1998). Based on morphology it has been suggested that the main inputs to the central complex are through large field tangential neurons and that main output channels are through columnar elements, while pontine neurons are believed to be intrinsic elements connecting columns and layers within the central complex (Hanesch et al, 1989;Heinze and Homberg, 2008).…”