Anatomy & Physiology: Current Research
Open Access

Abstract

Relationship between the Early Toothless Condition and Hippocampal Functional Morphology

Mitsuo Iinuma, Hiroko Kondo, Minori Kurahashi, Mika Ohnishi, Yasuo Tamura, Huayue Chen and Kin-ya Kubo

Hippocampus is important for learning and memory. This article reviews the recent progress of the relationship between the toothless condition and the hippocampal functional morphology. Tooth loss early in life was generated by extracting the upper molars shortly after tooth eruption in mice or rat. Morphological and physiological studies showed that early toothlessness, acting as a chronic stress, induced constantly elevated levels of corticosterone, leading to morphological and molecular alterations in hippocampus, accompanied by deficits in spatial learning and memory. The early toothlessness may be a risk factor of cognitive impairment. Adequate dental treatments such as denture or dental implants for defective part of teeth are considered to be important for maintaining the hippocampal functions. The possible mechanism of the hippocampal alterations induced by early toothless condition is also discussed.