Impairment of PGC-1α-mediated mitochondrial biogenesis precedes mitochondrial dysfunction and Alzheimer's pathology in the 3xTg mouse model of Alzheimer's disease.

Impairment of mitochondrial biogenesis and mitochondrial dysfunction is a prominent feature of Alzheimer's disease (AD). However, the extent to which the impairment of mitochondrial biogenesis influences mitochondrial dysfunction at the onset and during progression of AD is still unclear. Our study demonstrated that the protein expression pattern of the transcription factor pCREB/CREB, together with the protein expression of PGC-1α, NRF1 and TFAM are all significantly reduced in early ages of 3xTg-AD mice. We also found reduced mRNA expression levels of PKAC-α, CREB, PGC-1α, NRF1, NRF2 and TFAM as early as 1 month-of-age, an age at which there was no significant Aß oligomer deposition, suggesting that mitochondrial biogenesis is likely impaired in ages preceding the development of the AD pathology. In addition, there was a decrease in VDAC2 expression, which is related to mitochondrial content and mitochondrial function, as demonstrated by protein expression of complex IV, as well as complex II + III, and complex IV activities, at later ages in 3xTg-AD mice. These results suggest that the impairment in mitochondrial biogenesis signaling mediated by PGC-1α at early ages of the AD mice model likely resulted in mitochondrial dysfunction and manifestation of the AD pathology at later ages. Taken together, enhancing mitochondrial biogenesis may represent a potential pharmacological approach for the treatment of AD.

Motor improvement requires an increase in presynaptic protein expression and depends on exercise type and age.

The aging process is associated with structural and functional changes in the nervous system. Considering that exercise can improve the quality of life of the elderly, the aim of this study was to evaluate the effects of exercise protocols with different motor demands on synaptic protein expression (i.e., synapsin-I and synaptophysin). Cognitive and motor brain areas and the motor performance of adult and aged animals were analyzed. Adult (7 months old) and aged (18 months old) male Wistar rats were used. Animals were divided into the following groups: treadmill exercise (TE, rhythmic motor activity), acrobatic exercise (AE, complex motor activity) and sedentary (SED, control). The animals were exposed to exercise 3 times per week for 8 weeks. The brains were collected for immunohistochemistry and immunoblotting assays. Our results showed that both types of exercise induced changes in motor performance and synaptic protein expression in adult and aged animals. However, acrobatic exercise promoted a greater number of changes, mainly in the aged animals. In addition, protein expression changes occurred in a greater number of brain areas in the aged animals than in adult animals. There were clear increases in synapsin-I expression in all areas analyzed of aged animals only after acrobatic exercises. On the other hand, synaptophysin increased in the same areas but with both types of exercise. Thus, in general, our data suggest that even at advanced ages, when the aging process is already in progress, initiating physical training may be beneficial to generate neuroplasticity that can improve motor performance.

Treadmill Exercise Prevents Increase of Neuroinflammation Markers Involved in the Dopaminergic Damage of the 6-OHDA Parkinson's Disease Model.

Parkinson's disease (PD) involves loss of dopaminergic neurons in the substantia nigra (SN), which can be correlated to neuroinflammatory changes with the aging of the nervous system. On the other hand, exercise can reduce the deleterious effects promoted by age, but the mechanism involved is still unclear. This study investigated the preventive exercise-induced changes on neuroinflammatory processes in a rat model of PD induced by unilateral striatal injections of 6-hydroxydopamine (6-OHDA). Adult male Wistar rats were divided into two groups: (1) sedentary (SED) or (2) exercised (EX), animals that did treadmill exercise three times per week, every other day, for 4 weeks prior to 6-OHDA or saline injection. The rats were then divided into four sub-groups: (1) sedentary saline (SED), (2) sedentary 6-OHDA (SED + 6-OHDA), (3) exercised saline (EX), and (4) exercised 6-OHDA (EX + 6-OHDA). Seven and 30 days after surgery, brains were collected for immunohistochemistry and immunoblotting for dopaminergic and neuroinflammatory markers into SN and striatum. The SED + 6-OHDA animals presented an increase in the astrocyte, microglial, and oxidative species activation. On the other hand, EX + 6-OHDA animals did not present neuroinflammatory responses and performed better apormorphine test. Our data suggest that treadmill exercise throughout life can markedly reduce the chances of dopamine decrease, reinforcing studies that showed a lower incidence of Parkinson's disease in patients who were active during life.