Peptidergic activation of locust dorsal unpaired median neurons: Depolarization induced by locustatachykinins may be mediated by cyclic AMP
✍ Scribed by Lundquist, C. Tomas ;N�ssel, Dick R.
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 684 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0022-3034
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✦ Synopsis
Four tachykinin-related peptides, Amino-terminally truncated forms of LomTK 1 were locustatachykinin 1-4 (LomTK 1-4) are distributed applied to DUM neurons. The heptapeptide [3-9]in interneurons throughout the central nervous sys-LomTK 1 had a substantially reduced activity, and tem of the locust Locusta migratoria and may have bioactivity was lost after further truncation. Spantide important roles as neurotransmitters or neuromodu-1, an antagonist of mammalian tachykinin receptors, lators. In search of the central actions of LomTKs, we reversibly blocked the effect of LomTK 1. The effect analyzed the response of the efferent dorsal unpaired of LomTK 1 was clearly reduced in the presence of median (DUM) neurons in the locust metathoracic GDP-ß-S, a stable analog of GDP that inactivates Gganglion. Immunocytochemistry, using an antiserum proteins. The action of LomTK 1 was potentiated by against LomTK 1, combined with intracellular filling both IBMX and theophylline, two cyclic AMP of efferent DUM neurons with Lucifer yellow, re-(cAMP) phosphodiesterase inhibitors. The action of vealed that LomTK-immunoreactive fibers are in LomTK 1 was mimicked by pressure-ejecting 8close proximity to dendritic arborizations of the DUM bromo-cAMP, a membrane permeable analog of neurons. Hence, LomTKs may act on DUM neurons cAMP, and by forskolin, an adenylate cyclase activaby releasing locally in the metathoracic ganglion. Intor. Furthermore, cAMPS, a blocker of protein kinase tracellular recordings were made from somata of A activity, reduced the effect of LomTK 1. These find-DUM neurons, and LomTKs were either bath-applied ings indicate that cAMP is involved in mediating DUM to an isolated metathoracic ganglion or pressureneuron depolariztion. ᭧ 1997 John Wiley & Sons, Inc. J ejected onto the DUM neuron soma. LomTK 1 at con-