title: [Changes in ingestive behavior during growth affects the functional maturation of temporomandibular joint nociceptive neurons of rats].
abstract: Temporomandibular joint (TMJ) loading during development promotes its growth and maintains normal structure/function. Continuous change in diet consistency is related to development and maturation of the peripheral nervous system, including the nociceptive system. However, the functional modulation of TMJ-nociceptive neurons under different ingestive behavior is unclear. We fed growing rats a liquid diet to investigate the effects of low TMJ loading on the response properties of neurons in the trigeminal spinal tract subnucleus caudalis (Sp5C). Forty 2-week-old male rats were used. They were fed chow pellets (n = 20, C group) or a liquid diet (n = 20, LD group) soon after weaning. Firing activities of single sensory units in response to TMJ pressure stimuli were recorded at 4, 5, 7 and 9 weeks. In TMJ-nociceptive neurons, the firing threshold (FT) in the LD group was significantly lower than that in the C group at each recording age. The FT in the C group remained unchanged throughout the recording period, whereas that in the LD group was the highest at 4 weeks, and gradually decreased. On the other hand, the initial firing frequency (IFF) was significantly higher in the LD group than in the C group at each recording age. The IFF in the C group remained unchanged throughout the experimental period, whereas that in the LD group was at its lowest at 4 weeks, and gradually increased. Based on these findings, ingestive behavior that results from continuous changes in the physical consistency of the diet during growth may affect the functional maturation of TMJ-nociceptive neurons.
authors: Section of Orthodontic Science, Department of Orofacial Development and Function, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University.
authors: Maya
authors: M
authors: Hiranuma
mesh_terms: D000818:Animals; D004032:Diet; D005247:Feeding Behavior / Q000502:physiology*; D008297:Male; D009619:Nociceptors / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013704:Temporomandibular Joint / Q000294:innervation*