Submitted to: Journal of Neuroscience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/1999
Publication Date: N/A
Interpretive Summary: Nerve cells that produce compounds called neuropeptides were found for the first time in the antennae of an insect, the mosquito, Culex salinarius. Neuropeptides are small chains of amino acids, the building blocks of proteins, and neuropeptides are known to regulate most vital body functions in insects such as water balance, water movement, etc. The species of mosquitos studied is a vector of two important diseases, eastern equine encephalitis and St. Louis encephalitis. The structure of the nerve cells is unique in that they not only send messages to the brain but also directly influence the response of nerve cells in the antennae that locate food and mates. These studies are important because they have resulted in the discovery of another target for the development of neuropeptide-based insect control chemicals that will be toxic only to the pest insect, and safe to the environment.
Technical Abstract: An antiserum raised against the peptide, culetachykinin II immunocytochemically detected a group of neurosecretory cells in the first flagellar segment of the antennae of both males and females of the mosquito Culex salinarius. This is the first insect species in which neurosecretory cells have been found in the antennae. The ultrastructure of these antenna aneurosecretory cells (ANC) is described as well as their relationship to o neurons in the antennae and antennal lobe of the mosquito. These tachykinin-reactive cells contain relatively small (140-220 nm) elementary neurosecretory granules. Not only do the ANC have axons that terminate on specific glomeruli of the deutocerebrum, but these neurons also have collaterals that form neurohemal terminals in the receptor lymph channels o the dendrites of the sensory neurons. Thus, the ANC not only influence high centers of the brain that interpret signals from the antennal sensillae, bu ualso modulate the response of the sensory receptors. To our knowledge, thi the first report of neurosecretory cells directly affecting the signal reception of sensory neurons.