Features of Mitochondrial Dynamics Changes in Large Pyramidal Neurons of the Human Motor Cortex during Aging.

TOMM20 staining intensity was decreased in large pyramidal neurons of the motor cortex in aged individuals compared to controls.

• Study used autopsy material from individuals aged 75 years and older as the aging group.
• Control group consisted of individuals aged 35-44 years who died from sudden cardiac death.
• TOMM20 is used as a marker of mitochondrial mass/pool volume.
• Decreased TOMM20 staining was interpreted as indicating a reduction in the mitochondrial pool volume.

Opa1 staining intensity was decreased in large pyramidal neurons of the motor cortex during aging.

• Opa1 is a marker of mitochondrial inner membrane fusion.
• The decrease was observed in layer V pyramidal neurons of the human motor cortex.
• Reduced Opa1 was interpreted as indicating dysfunction in the mitochondrial fusion process.
• Impaired fusion was suggested to impede organelle growth, contributing to reduced mitochondrial pool volume.

Drp1 staining intensity was increased in large pyramidal neurons of the motor cortex during aging.

• Drp1 is a marker of mitochondrial fission.
• Increased Drp1 staining was observed in layer V large pyramidal neurons of the motor cortex.
• This finding was interpreted as indicating enhanced mitochondrial fragmentation in aged individuals.
• The increase in fission marker combined with decreased fusion marker indicates a shift toward fission during aging.

Mfn1 and Mfn2 staining intensities were also evaluated in the study of mitochondrial dynamics during aging.

• Mfn1 and Mfn2 are markers of mitochondrial outer membrane fusion.
• The proteins were assessed by immunohistochemical staining in large pyramidal neurons of the human motor cortex.
• Results for Mfn1 and Mfn2 were not explicitly highlighted as significantly changed in the abstract, in contrast to Opa1, Drp1, and TOMM20.
• The study assessed five mitochondrial dynamics-related proteins in total: TOMM20, Drp1, Mfn1, Mfn2, and Opa1.

Mitochondrial fragmentation in pyramidal neurons of layer V of the motor cortex during aging may be associated with dysfunction in the mitochondrial fusion process.

• The combined pattern of decreased TOMM20 and Opa1 with increased Drp1 was interpreted as indicating enhanced mitochondrial fragmentation.
• The authors suggest this fragmentation is possibly associated with a reduction in the mitochondrial pool volume.
• Dysfunction in mitochondrial fusion was proposed to impede organelle growth.
• The study material was from the motor cortex, focusing specifically on large pyramidal neurons in layer V.