BACKGROUND: Hyperglycemia impaired hippocampal network via triggering suicide program of immanent neurons, this is regarded as an etiological factor for diabetic cognition deficits. AIM: To investigate the occurrence of apoptosis in the hippocampal dentate gyrus of streptozotocin (STZ)-induced diabetic rats with cognitive impairment and assess the gene and protein expression of the apoptotic proteins bax, bcl-2, and caspase-3. MATERIALS AND METHODS: Four weeks after the verification of STZ-induced diabetes, diabetic rats with and without cognitive decline subgroups were subsequently assigned according to Morris water maze test. The expression levels of apoptotic proteins were measured using real-time RT-PCR and western blotting, respectively. Neuronal apoptosis was detected by TUNEL staining and electron microscopy. RESULTS: In the dentate gyrus of the rats with cognitive decline, Bcl-2 exhibited lower gene and protein levels, whereas a higher expression of bax was detected contributing to a significant increase in their mean bax/bcl-2 ratio. However, caspase-3 was not activated. Statistically different numbers of TUNEL-staining cells and features of apoptosis were no found. CONCLUSIONS: The higher bax/bcl ratio probably represents neurons of dentate gyrus vulnerable to apoptosis in the diabetes with cognitive decline. However, the normal caspase-3 level suggests that apoptosis is not active in this illness phase.
BACKGROUND:Hyperglycemia impaired hippocampal network via triggering suicide program of immanent neurons, this is regarded as an etiological factor for diabetic cognition deficits. AIM: To investigate the occurrence of apoptosis in the hippocampal dentate gyrus of streptozotocin (STZ)-induced diabeticrats with cognitive impairment and assess the gene and protein expression of the apoptotic proteins bax, bcl-2, and caspase-3. MATERIALS AND METHODS: Four weeks after the verification of STZ-induced diabetes, diabeticrats with and without cognitive decline subgroups were subsequently assigned according to Morris water maze test. The expression levels of apoptotic proteins were measured using real-time RT-PCR and western blotting, respectively. Neuronal apoptosis was detected by TUNEL staining and electron microscopy. RESULTS: In the dentate gyrus of the rats with cognitive decline, Bcl-2 exhibited lower gene and protein levels, whereas a higher expression of bax was detected contributing to a significant increase in their mean bax/bcl-2 ratio. However, caspase-3 was not activated. Statistically different numbers of TUNEL-staining cells and features of apoptosis were no found. CONCLUSIONS: The higher bax/bcl ratio probably represents neurons of dentate gyrus vulnerable to apoptosis in the diabetes with cognitive decline. However, the normal caspase-3 level suggests that apoptosis is not active in this illness phase.
Authors: Andrea Pereira Rosa; Caroline Paula Mescka; Felipe Maciel Catarino; Alexandre Luz de Castro; Rayane Brinck Teixeira; Cristina Campos; Guilherme Baldo; Débora Dalmas Graf; Angela de Mattos-Dutra; Carlos Severo Dutra-Filho; Alex Sander da Rosa Araujo Journal: Metab Brain Dis Date: 2017-12-19 Impact factor: 3.584