Soft-diet feeding after weaning affects behavior in mice: Potential increase in vulnerability to mental disorders

The impact of mastication on cognition: Evidence for intervention and the role of adult hippocampal neurogenesis

“…However, a study that also found reduced BDNF levels in soft diet fed mice did not find the mice to have defective cognitive function, but instead have affected physical and mental development, which may cause an increased vulnerability to mental disorders [19]. Yet it is noted that their results are inconsistent with other studies, which demonstrate reduced performance in cognitive tasks, with long term soft diet feeding, and propose that this is due to the study having a relatively short period of soft diet feeding in comparison [19]. A study investigating the effects of molar removal on mice AHN showed impaired distribution, structure and neurogenic capacity of neurons in the DG when measured by doublecortin and neuronal nuclear antigen, with these impairments possibly having a negative effect on learning and memory [9].…”

“…Brain-derived neurotrophic factor (BDNF) is one of the many signaling molecules involved in regulating AHN [14,18]. Interestingly, it has been demonstrated in studies that soft-diet feeding in mice leads to altered expression of BDNF and its receptor, Tryosine receptor kinase B (TrkB), in the hippocampus and restrained AHN, which resulted in behavioral impairments [12,19]. Impairment of this process results in impaired memory function, and studies involving ablation of these neurons demonstrates this.…”

“…Animal Model Intervention Outcome [10] Wistar rats Soft diet Cell proliferation in the dentate gyrus is suppressed by soft diet feeding [19] C57BL/6 mice Soft diet Soft diet mice showed behavioural impairments, such as decreased home cage activity, increased open field test activity, and deficits in prepulse inhibition, but no impairments in memory and learning. Decreased cell proliferation in the hippocampus, BDNF and Akt1 (protein kinase B) gene expression [36] C57BL/6 mice Hard diet Improved spatial learning ability of hard diet mice.…”

“…Experimental studies discussed, mainly done on mice, have consistently shown that impairing masticatory function results in both cellular and behavioural changes. A recurring theme identified is that of a decrease in neural stem cells proliferation in the hippocampus in many of the animal studies, when masticatory impairment was simulated by feeding mice a soft/powdered/liquid diet [10,19,33,34].…”

“…The disruption in BDNF/TrkB signalling leads to reduced induction of the MAPK cascade, which is necessary for memory and learning, and the findings suggest that the reduction of BDNF/TrkB signalling decreases the number of neuronal cells in the hippocampus, resulting in impaired memory and learning ability [33]. However, a study that also found reduced BDNF levels in soft diet fed mice did not find the mice to have defective cognitive function, but instead have affected physical and mental development, which may cause an increased vulnerability to mental disorders [19]. Yet it is noted that their results are inconsistent with other studies, which demonstrate reduced performance in cognitive tasks, with long term soft diet feeding, and propose that this is due to the study having a relatively short period of soft diet feeding in comparison [19].…”