Effect of Experimental Removal of Molars on Gastric and Submaxillary Salivary Secretion in the Rat

Gyimesi, Judit; Zelles, T; Keszler, P

doi:10.1177/00220345740530053501

Cited by 3 publications

(3 citation statements)

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“…Another possible hypothesis supporting the attenuated DA system in the molarless mice is iron deprivation caused by extraction-induced reduction of gastric acid secretion [10]. The iron is a key element in DA synthesis, and DA deficit in the brain is generally recognized as a pivotal for hyperactivity and pathologic lateralization of cognitive functioning that are commonly observed in attention-deficit/hyperactivity disorder (ADHD) [34].…”

Section: Discussionmentioning

confidence: 99%

“…Impaired masticatory function due to tooth loss causes dietary deficiencies among older adults (reviewed in [3,4]), and the consequent malnutrition status increases the risk of developing cognitive impairment [5,6]. Experimental results in young adult rodents also demonstrate that permanent loss of functional teeth for months impairs digestive and absorptive function by altering the maxillomandibular relationship [7,8] and by reducing secretion of saliva and gastric acid [9,10], even though having teeth extracted does not reduce food consumption [11]. However, the relationship between impaired masticatory function and cognitive deficit for younger individuals remains unclear.…”

Section: Introductionmentioning

confidence: 99%

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Loss of molars early in life develops behavioral lateralization and impairs hippocampus-dependent recognition memory

et al. 2014

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BackgroundUsing senescence-accelerated mouse prone 8 (SAMP8), we examined whether reduced mastication from a young age affects hippocampal-dependent cognitive function. We anesthetized male SAMP8 mice at 8 weeks of age and extracted all maxillary molar teeth of half the animals. The other animals were treated similarly, except that molar teeth were not extracted. At 12 and 24 weeks of age, their general behavior and their ability to recognize novel objects were tested using the open-field test (OFT) and the object-recognition test (ORT), respectively.ResultsThe body weight of molarless mice was reduced significantly compared to that of molar-intact mice after the extraction and did not recover to the weight of age-matched molar-intact mice throughout the experimental period. At 12 weeks of age, molarless mice showed significantly greater locomotor activity in the OFT than molar-intact mice. However, the ability of molarless mice to discriminate a novel object in the ORT was impaired compared to that of molar-intact mice. The ability of both molarless and molar-intact SAMP8 mice to recognize objects was impaired at 24 weeks of age. These results suggest that molarless SAMP8 mice develop a deficit of cognitive function earlier than molar-intact SAMP8 mice. Interestingly, both at 12 and 24 weeks of age, molarless mice showed a lateralized preference of object location in the encoding session of the ORT, in which two identical objects were presented. Their lateralized preference of object location was positively correlated with the rightward turning-direction preference, which reached statistical significance at 24 weeks of age.ConclusionsLoss of masticatory function in early life causes malnutrition and chronic stress and impairs the ability to recognize novel objects. Hyperactivation and lateralized rotational behavior are commonly observed with dysfunction of the dopaminergic system, therefore, reduced masticatory function may deplete the mesolimbic and mesocorticolimbic dopaminergic systems to impair the cognitive functions of selective attention and recognition memory in the prefrontal cortex and the hippocampus.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Loss of molars early in life develops behavioral lateralization and impairs hippocampus-dependent recognition memory

et al. 2014

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“…Reduced mastication might alter cognitive function via malnutrition especially in case of extraction. Loss of functional teeth for months impairs digestive and absorptive function by altering the maxillomandibular relationship (43, 44) and by reducing secretion of saliva and gastric acid (45, 46), even though having teeth extracted does not cause the rodents to consume less food (13). However, recent evidence suggests that moderately restricting calories acts to protect against age‐related hippocampal deficits (47–50).…”

Section: Masticatory Modulation Of Learning and Memorymentioning

confidence: 99%

Occlusion and brain function: mastication as a prevention of cognitive dysfunction

Ono

Yamamoto

Kubo

et al. 2010

Journal of Oral Rehabilitation

163

188

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Research in animals and humans has shown that mastication maintains cognitive function in the hippocampus, a brain area important for learning and memory. Reduced mastication, an epidemiological risk factor for the development of dementia in humans, attenuates spatial memory and causes hippocampal neurons to deteriorate morphologically and functionally, especially in aged animals. Active mastication rescues the stress-attenuated hippocampal memory process in animals and attenuates the perception of stress in humans by suppressing endocrinological and autonomic stress responses. Active mastication further improves the performance of sustained cognitive tasks by increasing the activation of the hippocampus and the prefrontal cortex, the brain regions that are essential for cognitive processing. Abnormal mastication caused by experimental occlusal disharmony in animals produces chronic stress, which in turn suppresses spatial learning ability. The negative correlation between mastication and corticosteroids has raised the hypothesis that the suppression of the hypothalamic-pituitary-adrenal (HPA) axis by masticatory stimulation contributes, in part, to preserving cognitive functions associated with mastication. In the present review, we examine research pertaining to the mastication-induced amelioration of deficits in cognitive function, its possible relationship with the HPA axis, and the neuronal mechanisms that may be involved in this process in the hippocampus.

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On the relationship between chitin particle size and digestibility in the primate Galago senegalensis

Kay

Sheine

1979

American J Phys Anthropol

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Experiments were performed to examine the relationship between the particle size of chitin and its digestibility in the small insectivorous prosimian Galago senegalensis. In the first set of experiments, four animals were fed a 25% chitin diet with the chitin particles less than or equal to 60mesh (0.250 mm maximum diameter). On average, the animals digested 22.5 -+ 2.2 percent of the ingested chitin. In the second set of experiments, the four animals were fed a 25% chitin diet with the chitin particles ground to S 4 0 -and 245-mesh (between 0.425 and 0.325 mm). On average, the animals digested 2.75 -t 1.38 percent of the ingested chitin. There was no significant variation between the performance of any of the animals on either the 60-or 40-45-mesh trials. In all instances, however, each animal digested significantly more of the 60-mesh chitin and the 40-45-mesh chitin.These experiments demonstrate the importance of masticatory efficiency among small mammals for improving the digestibility of foods such as insects which contain high proportions of chitin. They also suggest why insectivorous and folivorous primates have certain convergent dental specializations for finely grinding their foods. Both leaves and insects contain relatively indigestible structural carbohydrates. These substances are much more completely digested when the surface area to volume ratio of the swallowed material is increased. The masticatory efficiency of frugivorous primates is much lower since the constituents of these foods are relatively completely digested irrespective of the fineness of grinding.Recently, it has been shown that insectivorous primates masticate their foods more efficiently than do comparable sized frugivorous species (Sheine and Kay, '77). It was suggested that this provided more surface area for the action of digestive enzymes and enhanced the assimilation of chitin, a major component of insect exoskeletons. To confirm this hypothesis there must be evidence that there are chitinolytic enzymes in these species and that the digestibility of chitin increases as its surface-area to volume ratio is increased. The first of these requirements has been met. Beerton-Joly e t al. ('74) showed that there is a strong chitinolytic activity in the AM. J. PHYS, ANTHROP. (1979) 50: 301-308

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Effect of Experimental Removal of Molars on Gastric and Submaxillary Salivary Secretion in the Rat

Abstract: The absence of molars decreased HCl acid content of the stomach and histamine concentration in the gastric wall. Dry and wet weight of the submaxillary gland did not change, but the rate of secretion decreased significantly in rats without molars. A de-

Cited by 3 publications

References 9 publications

Loss of molars early in life develops behavioral lateralization and impairs hippocampus-dependent recognition memory

Loss of molars early in life develops behavioral lateralization and impairs hippocampus-dependent recognition memory

Occlusion and brain function: mastication as a prevention of cognitive dysfunction

On the relationship between chitin particle size and digestibility in the primate Galago senegalensis

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