Serotonin-like immunoreactivity in the central nervous system of two ixodid tick species.
Immunocytochemistry was used to describe the distribution of serotonin-like immunoreactive (5HT-IR) neurons and neuronal processes in the central nervous system (CNS), the synganglion, of two ixodid tick species; the winter tick, Dermacentor albipictus and the lone star tick, Amblyomma americanum. 5HT-IR neurons were identified in the synganglion of both tick species. D. albipictus had a significantly higher number of 5HT-IR neurons than A. americanum. The labeling pattern and number of 5HT-IR neurons were significantly different between sexes in D. albipictus, but were not significantly different between sexes in A. americanum. 5HT-IR neurons that were located in the cortex of the synganglion projected processes into the neuropils, invading neuromeres in the supraesophageal ganglion including the protocerebrum, postero-dorsal, antero-dorsal and cheliceral neuromeres. In the subesophageal ganglion, dense 5HT-IR neuronal processes were found in the olfactory lobes, pedal, and opisthosomal neuromeres. Double-labeling with neurobiotin backfilled from the first leg damaged at the Haller's organ revealed serotoninergic neuronal processes surrounding the glomeruli in the olfactory lobes. The high number of the 5HT-IR neurons and the extensive neuronal processes present in various regions of the synganglion suggest that serotonin plays a significant role in tick physiology.
ARS, Knipling-Bushland US Livestock Insects Research Laboratory, USDA, 2700 Fredericksburg Road, Kerrville, TX 78028, USA. nhummel@agcenter.lsu.edu
Natalie A
NA
Hummel
Andrew Y
AY
Li
Colleen M
CM
Witt
D000818:Animals; D001710:Biotin / Q000031:analogs & derivatives / Q000737:chemistry; D001921:Brain / Q000502:physiology; D002490:Central Nervous System / Q000502:physiology*; D005260:Female; D007150:Immunohistochemistry; D026863:Ixodidae / Q000502:physiology*; D008297:Male; D018613:Microscopy, Confocal; D009474:Neurons / Q000737:chemistry / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*
C070614:neurobiotin; D012701:Serotonin; D001710:Biotin