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Updated: Feb 5, 2026

Primary Culture of Hippocampal Neurons from P0 Newborn Rats
Published on: September 29, 2008
Masticatory hypofunction effects induced by BTXA injection of hippocampal neurons in developing rats
Chi-Yang Tsai1, Hsin-Ping Lee1, Hung-Ming Chang2
1Department of Orthodontics, Department of Dentistry, Taipei Medical University Hospital, Taipei, Taiwan; Graduate Institute of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan.
Background And Objective:
In clinical practice, malocclusion is often encountered during the period of growth and development of individuals. In addition to nutritional imbalance, some studies have found that mastication affects learning and memory ability. Tooth loss and masticatory hypofunction have been suggested as risk factors of Alzheimer disease. However, relatively little research has been done in developing animals. The present study evaluated the relationship between masticatory hypofunction and neuropathological changes of the hippocampus in developing rats.
Design:
Four-week-old Wistar rats were randomly divided into saline-injected and botulinum toxin type A (BTXA)-injected groups. After an experiment period of 4 weeks, the rats were sacrificed for evaluation of neuropathological changes in the hippocampus through Nissl staining and phosphorylated cyclic AMP (cAMP) response element binding protein (CREB) immunohistochemistry.
Results:
Nissl staining revealed a significant reduction in the density of neurons in the BTXA-injected rats. The BTXA-injected rats exhibited a decreased level of CREB phosphorylation. The degree of p-CREB immunoreactivity differed significantly between the two groups.
Conclusion:
The BTXA-injected rats exhibited a reduction in neuron density and phosphorylated CREB, indicating that mastication might influence the learning and memory ability during the growth period. Therefore, it is strongly suggested that malocclusion be corrected as soon as possible during growth and development.
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