Effects of Long-Term Intake of a Fine-Grained Diet on the Mouse Masseter Muscle

Maeda, Norihiko; Kawasaki, Takahide; Osawa, Koichi; Yamamoto, Yoshiro; Sumida, H; Masuda, Tamuro; Kumegawa, Masayoshi

doi:10.1159/000146360

Cited by 48 publications

(37 citation statements)

References 13 publications

(18 reference statements)

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“…Ishizuka (5) demonstrated that the action potential of the masseter muscle was less substantial during mastication and the total duration of muscle activity was significantly shorter in powder-diet rats compared with the soliddiet ones. This was explained by the delayed growth of the masseter muscle spindle in the powder-diet group (8). Since reduced afferent stimuli occur by the decrease in stimulation from the muscle spindle, it is considered that long term soft-diet intake may seriously influence a decrease in the number of neurons.…”

Section: Discussionmentioning

confidence: 99%

Influences of reduced masticatory sensory input from soft-diet feeding upon spatial memory/learning ability in mice

et al. 2007

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It has been reported that reduction of masticatory afferent stimulation might influence learning and memory function. In order to clarify the influences of reduced masticatory sensory input on spatial memory/learning ability and neuropathological changes, we conducted the Morris water maze experiment and investigated the number of hippocampal neurons in association with the differences in masticatory afferent stimuli from hard-and soft-diet feeding in mice. The water maze experiment showed no significant difference in learning ability between 180-day-old solid-and powderdiet groups. Meanwhile, the ability was significantly reduced in the 360-day-old powder-diet group as compared with the age-matched solid-diet group. The total number of pyramidal cells in the hippocampal CA1 and CA3 regions was significantly smaller in 360-day-old powder-diet group than in the remaining groups. These results demonstrate that reduction of masticatory afferent stimuli due to long-term soft-diet feeding may induce neuron loss in the hippocampus and reduced memory/learning ability.Alzheimer's disease (AD) is a progressive neurodegenerative disorder, which was first reported by Alzheimer in 1907 (1, 18). It is, in general, divided into early and late-onset types, but both have similar clinical and pathological features. It has long been suggested that there is a certain relationship between loss of teeth and dementia. Kondo et al. (6) reported that tooth loss was one of the risk factors of AD. Shigetomi et al. (17) reported that the risk of AD onset increased significantly in a group with lessnumber teeth than in the age-matched control with more-number teeth. Animal experiments revealed that tooth loss or long-term soft-diet feeding caused a decrease of learning and memory ability. Yamamoto and Hirayama showed that the SAMR1 and SAMP8 mice fed on a solid diet were superior in an eight-arm radial maze to the powder-diet group (21). It was also reported that the aged SAMP8 mice, after the molar extraction, showed a decrease in both learning ability and neuron density in the hippocampal CA1 region compared with the controls (14). Furthermore, it is suggested that afferent sensory input is highly dependent on masticatory function or hardness of the diet (13). Ishizuka (5) demonstrated that the action potential of the masseter muscle in rats was significantly lower in the powder-diet group than in the solid-diet group.It is reasonably assumed from these findings that tooth loss and the relevant reduction of masticatory afferent stimuli may influence the structure and function of the central nervous system (CNS). However, little information is available for the relation-

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Section: Discussionmentioning

confidence: 99%

Influences of reduced masticatory sensory input from soft-diet feeding upon spatial memory/learning ability in mice

et al. 2007

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“…These models include hindlimb suspension (Asmussen and Soukup 1991;Asmussen et al 1989;Elder and McComas 1987;Huckstorf et al 2000;Mozdziak et al 2000;Ohira et al 2001;Saitoh et al 1999;Walton et al 1992), spaceflight (Adams et al 2000), or antagonist muscle removal (Lowrie et al 1989) to study the soleus and restricting animals to a soft diet to study the masseter Maeda et al 1987;Miyata et al 1993). In general, a reduction in load or activity level produces a decrease in muscle fiber size and a shift toward faster muscle fiber types.…”

Section: Introductionmentioning

confidence: 99%

Effect of Artificial Rearing on the Contractile Properties and Myosin Heavy Chain Isoforms of Developing Rat Tongue Musculature

Kinirons¹,

Shall²,

McClung³

et al. 2003

Journal of Neurophysiology

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. Effect of artificial rearing on the contractile properties and myosin heavy chain isoforms of developing rat tongue musculature. J Neurophysiol 90: 120 -127, 2003; 10.1152/jn.00809.2002. This study's purpose was to examine the influence of an altered activity level, via artificial rearing, on the contractile properties, myosin heavy chain phenotypes (MHC), and muscle fiber sizes of the developing rat tongue retractor musculature. Artificially reared rat pups were fed through a gastric cannula, eliminating nutritive suckling from postnatal day 4 to postnatal day 14. Rat pups were observed immediately following artificial rearing (postnatal day 14) and after a 1-mo resumption of function (postnatal day 42). The contractile characteristics of the tongue retractor musculature were measured in response to stimulation of the hypoglossal nerve. At postnatal day 14, artificially reared rat pups demonstrated significantly longer twitch half-decay times, lower fusion frequencies, and a marked decrease in fatigue resistance. These contractile speed and fatigue characteristics were fully recovered following a 1-mo resumption of function. MHC phenotypes of the styloglossus muscle (a tongue retractor) were determined by gel electrophoresis. At postnatal day 14, artificial rearing had not altered the MHC phenotype or muscle fiber sizes of the styloglossus muscle. However, following a 1-mo resumption of function artificially reared rat pups demonstrated a small but significant increase in MHCIIa expression and decrease in MHCIIb expression compared with dam-reared rats. These results support artificial rearing as a useful model for altering the activity level of the tongue and suggest that normal suckling behavior is necessary for the normal postnatal development of the tongue retractor musculature. This may also be the case for premature infants necessarily fed artificially.

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“…3 Maeda et al reported that the masseter muscle was atrophied in the mice with extraction of unilateral molars and in the osteopetrotic (op/op) mouse with no eruption of teeth and less-developed periodontal ligaments. [20][21][22] On the other hand, there is significant decrease in the number of jaw closing motoneurons innervating the masseter muscle in 3-and 5-month-old op/op mice. 15 Masticatory sensory neurons were also less in number in the 3-month-old op/op mouse, as compared with those in the normal mouse.…”

Section: Discussionmentioning

confidence: 97%

Reduction of Masticatory Neurons in the Tooth-extracted Mice: A Year-long Study

Rashid

Akhter²,

Maeda

2013

City Dent Coll J

Self Cite

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Abstract:Background: It has been reported that the number of masticatory motor and sensory neurons were seriously diminished and the masseter muscles were severely atrophied in the genetically mutant osteopetrotic (op/op) mouse with no eruption of teeth and less-developed periodontal ligaments. The present study was designed to observe whether the sensory input from the periodontal mechanoreceptive afferents be involved in the development and maintenance of the masticatory system. Methods: A case-control study was carried out with 2 groups of male ICR mice. Unilateral extraction of upper and lower molars was carried out in the case group on day 20 after birth. For assessing effects of tooth loss on the masticatory neurons, both mice groups were sacrificed on days 30, 60, 90, 120, 180 and 360 after birth and the trigeminal mesencephalic neurons (Me5) and trigeminal ganglion (TG) were traced and counted on both sides of the central nervous System (CNS). Results: In case group, severe degeneration of the ipsilateral inferior alveolar nerve (IAN) was observed on as early as day 40 after birth and there was significant decrease in the number of labeled Me5 and TG neurons between 60 th and 360 th postnatal days on the tooth-extracted side. Labeled primary afferent terminals were also severely diminished in the trigeminal sensory nuclear complex (TSNC) on the tooth-extracted side. Conclusion: Present study suggests that the decrease in the sensory input due to the tooth loss causes the disorder of the development and maintenance of the masticatory system even in the normal animal.

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Effects of Long-Term Intake of a Fine-Grained Diet on the Mouse Masseter Muscle

Cited by 48 publications

References 13 publications

Influences of reduced masticatory sensory input from soft-diet feeding upon spatial memory/learning ability in mice

Influences of reduced masticatory sensory input from soft-diet feeding upon spatial memory/learning ability in mice

Effect of Artificial Rearing on the Contractile Properties and Myosin Heavy Chain Isoforms of Developing Rat Tongue Musculature

Reduction of Masticatory Neurons in the Tooth-extracted Mice: A Year-long Study

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