IADR Abstract Archives

Different neurotransmitter release patterns in trigeminal ganglion neurons

Objectives: Mammalian nociceptors possess differential neurotrophin sensitivity and binding of the plant isolectin B4 (IB4). Most of the nerve growth factor-responsive IB4 (-) nociceptors contain neuropeptides such as substance P, whereas the glial derived growth factor-responsive IB4 (+) neurons predominantly lack such neuropeptides. We hypothesized that the difference in neuropeptide content between IB4 (+) and (-) neurons might be reflected in a difference in stimulated exocytosis and/or endocytosis.

Methods: We monitored the secretory activity of acutely dissociated neurons from adult rat trigeminal ganglia (TRG) using cell membrane capacitance (Cm) measurements and the fluorescent membrane-uptake marker FM4-64. Cm measurements were performed under whole-cell voltage clamp and neurons were depolarized to elicit exocytosis.

Results: Both types of TRG neurons showed similarly-sized, Ca²⁺-dependent Cm increases, demonstrating the capability for stimulated exocytosis in both IB4 (+) and (-) neurons. However, the peak Cm of IB4 (+) neurons decayed faster towards baseline than Cm of IB4 (-) neurons. Increasing intracellular Ca²⁺-buffering speeded up the Cm decay of both cell types. Also, IB4 (+) neurons had stable Cm responses to repeated stimuli whereas repeated stimulation of IB4 (-) neurons resulted in the loss of their secretory response. These data suggested different rates of endocytosis and vesicle replenishment for IB4 (+) and (-) nociceptors. To test this, we measured vesicle trafficking with FM4-64. IB4 (-) neurons exhibited a larger pool of endocytosed vesicles and their recycled vesicles released quicker than in IB4 (-) neurons.

Conclusions: The data suggest that IB4 (+) TRG neurons possess faster exocytosis, endocytosis and vesicle recycling, possibly due to differences in Ca²⁺-buffering.

Support contributed by Whitehall Foundation F98-34 (I.S.), NIH DE014573 (Y.M.), NIH NS41317 (F.S.).

Division: Japanese Division Meeting
Meeting: 2005 Japanese Division Meeting (Okayama, Japan)
Location: Okayama, Japan
Year: 2005
Final Presentation ID: 9
Abstract Category|Abstract Category(s): Scientific Groups

Authors

Matsuka, Yoshizo ( Okayama University, Okayama, N/A, Japan )

Kuboki, Takuo ( Okayama University, Okayama, N/A, Japan )

Maekawa, Kenji ( Okayama University, Okayama, N/A, Japan )

Kanyama, Manabu ( Okayama University, Okayama, N/A, Japan )

Ono, Mitsuaki ( Okayama University, Okayama, N/A, Japan )

Schweizer, Felix E. ( University of California - Los Angeles, Los Angeles, CA, USA )

Spigelman, Igor ( University of California - Los Angeles, Los Angeles, CA, USA )

SESSION INFORMATION

Oral Session
Periodontology, Microbiology, Neuroscience
11/26/2005