| Chronic pain in motor system disease generates
not only from inputs from noxious receptors
but also from emotional experiences and therefore
it is tightly related to autonomic nervous
system under control of hypothalamus (Autonomic
nervous center). Noxious stimuli from somatic
afferents activate muscle and splanchnic
sympathetic nerve activities, resulting in
failure of peripheral circulation due to
vasoconstriction. In addition, it is considered
that psychological stress worsens the failure
of peripheral circulation, although the underlying
mechanisms are still unknown. We focus on the bone, which is a pivotal mechanoreceptor and where autonomic and somatic nervous systems interact, and we plan to reveal the effects of mechanical stress on sympathetic nervous system and their underlying mechanisms. We built up co-culture system of osteoblasts and dorsal root ganglia (DRG) or superior cervical ganglia (SCG) neurons (Fig. 1). Interactions between osteoblastic cells and DRG or SCG neurons were monitored by changes of intracellular Ca2+ concentration ([Ca2+]i) under invert fluorescence microscopy after loading with the calcium fluorophore, Fluo-3 (Fig. 2). We confirmed the osteoblastic response to neural electrical stimulation (Fig. 3). We newly found neural afferent response to mechanical stimulation of osteoblast (Fig. 4). Now we present a summary of the most recent study: [Mechanical stimulation activates afferent pathways from osteoblasts to sensory neurons in in vitro co-culture system]. Keiji Asada, Koji Obata, Kumiko Aoki, Guo-Xing Zhang, Hiroko Matsuyoshi, Miyako Takaki Although histological studies reveal that sensory nerve fibres distribute to bone tissue, interactions between bone and nervous system remain unknown. We planned to study the mechanism of interactions between osteoblastic cells and sensory neurons in in vitro co-culture system. Primary sensory neurons were enzymatically isolated from DRG. Osteoblastic cells isolated from calvaria were co-cultured with DRG neurons for 24 hrs. Satellite cells were found around DRG neurons in this co-culture system. Interactions between DRG neurons and osteoblastic cells were monitored by changes in [Ca2+]i. Mechanical stimulation elicited instant increase in [Ca2+]i in osteoblastic cells. After a short delay, the increase of [Ca2+]i was observed in satellite cells and finally in DRG neurons. Pretreatment with a P2 receptor antagonist suppressed the increase of [Ca2+]i in satellite cells and DRG neurons. In conclusion, mechanical stimulation of bone tissue elicited signal transmission from osteoblasts to sensory neurons via afferent pathways including satellite cells and ATP. |
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| References | |
| 1. Keiji Asada, Koji Obata, Kumiko Aoki,
Guo-Xing Zhang, Hiroko Matsuyoshi, Miyako
Takaki: Afferent pathways from osteoblasts
to sensory neurons activated by mechanical
stimulation in co-culture system. J Physiol
Sci 60 (Suppl.1)S107: P14 (1P-J-14), 2010. |
