Neuronal co-localization of different isoforms of tachykinin-related peptides (LemTRPs) in the cockroach brain

Abstract

Seven isoforms of tachykinin-related peptides (TRPs) have been isolated from the brain of the cockroach Leucophaea maderae. These peptides (LemTRP-1, 2, and 5-9) share the C-terminal sequence GFX(1)GX(2)Ramide (where X(1) and X(2) are variable residues). In order to determine the neuronal distribution of several of these LemTRP isoforms, we raised antisera to their variable N-termini. Antisera to LemTRP-1, 2, 3, 7, and 8 were utilized for immunocytochemistry on cryostat sections of the L. maderae brain. As expected, the gut peptide LemTRP-3 was not detected in the brain, and the antisera to LemTRP-1, 2, and 7 labeled the same sets of neurons in different regions of the brain. These neurons could also be labeled with antisera raised to the more conserved C-termini of LemTRP-1 and the locust TRP LomTK-I. The antiserum to LemTRP-8 predominantly labeled a set of neurons distinct from that seen with any other N- or C-terminus-directed antisera, suggesting that it recognizes epitope(s) other than known insect TRPs. Our findings indicate that at least three of the LemTRPs are always co-localized in neurons of the L. maderae brain. We have also been able to show that LemTRP-2, which is an N-terminally extended form (17-mere) of LemTRP-1 with a dibasic putative cleavage site, is transported throughout the processes of the neurons in the same manner as LemTRP-1 and 7. Thus, LemTRP-2 may be released with the other shorter LemTRPs. This is the first investigation of LemTRP distribution in the cockroach central nervous system utilizing antisera to native peptides.

Salvage combination chemotherapy with 5‐fluorouracil and actinomycin D for patients with refractory, high‐risk gestational trophoblastic tumors

“…This pyrokinin, however, is not expressed in the brain region investigated (Meng et al, 2002). Thus, it is likely that multiple TRPs are produced by brain neurons of Drosophila , similar to findings in the brain of the cockroach Leucophaea maderae (Muren and Nässel, 1997; Nässel and Winther, 2002). Because there is no evidence for alternative splicing of the dtk gene (Siviter et al, 2000), it is likely that DTK‐1 to 5 are colocalized in the brain neurons and that they are possibly released together in equimolar concentrations.…”

Development of the Neurochemical Architecture of the Central Complex

“…At the single-cell level, neuroactive substances are also seen to co-localize in some instances. This is not unique as co-expression of neuropeptides has been extensively documented in insect nervous systems (e.g., Taghert and Truman, 1982a,b; Thompson et al, 1995; Duve et al, 2000; Nässel and Winther, 2002), including the central complex (Homberg et al, 1999), although co-localization does not necessarily imply co-release (Marder, 1999). …”

“…A relatively early expression of tachykinins has been reported for a range of insect nervous systems (Nässel and Winther, 2002; Nässel, 2002) and there is some evidence that members of the tachykinin family can act as neurotrophic factors (Satake et al, 2003), perhaps comparable to their role in the development of vertebrate respiratory networks (Wong-Riley and Liu, 2005). …”

Chemical neuroanatomy of the Drosophila central complex: Distribution of multiple neuropeptides in relation to neurotransmitters

“…LemTRP-1 shares the C-terminal sequence FXGXRamide with other tachykinin-related peptides and the antiserum has been shown to detect tachykinin-related peptides in Drosophila as well as in other insects Nässel and Winther, 2002;Winther et al, 2003). Specificity was tested by preabsorbing with synthetic LemTRP-1 and Drosophila tachykinin I (50 nmol/ mL antiserum), preabsorption abolished labeling (Winther et al, 2003).…”