本研究的目標是在探討面對壓力源，改變細胞增生和早期神經新生的性別差異與年齡相關的調節作用。在無法預期的足部電擊後進行水牢壓力，在此壓力測試後，我們計算小鼠齒狀回的細胞增生以及早期神經新生的數量。在壓力刺激測試前，分別在年輕（8週齡）和老年（9個月齡）的C57BL/ 6N小鼠進行立即性單一一劑的腹腔注射溴化去氧尿苷（BrdU）（100毫克/千克），作為神經細胞的標記。我們使用溴化去氧尿苷染色，它能夠標示出新生的有絲分裂產生的細胞，並且使用doublecortin共染色，它能夠標示出早期分化的神經原細胞。而我們發現不管是雄鼠或是雌鼠，老年的小鼠在細胞增生以及早期神經新生這兩個指標的數量都比年輕的小鼠擁有較低的水平。雖然年輕的小鼠對於壓力刺激的測試有較不敏感的現象，但是我們在老年的雌鼠對於壓力刺激的測試發現，老年的雌鼠在細胞增生以及早期神經新生的數量有明顯下跌的趨勢。另外，我們還發現在老年的雄鼠中，有年輕小鼠（8週齡）陪伴的或老年小鼠（9個月齡）陪伴的會增加壓力刺激的作用，使得細胞增生或早期神經新生的數目都有明顯下降的現象。綜合上述所示，我們的這些結果表明，相較於老年的雄鼠而言，在壓力的刺激下，老年的雌鼠對齒狀回內早期神經新生的調節作用可能較敏感。

This study aimed to assess sex differences and age-related modulating effect on the stressor-altered cell proliferation and early neuronal differentiation. Unpredicted foot shock followed by restraint in water was used as a stressor regimen and the number of cell proliferation and early neurogenesis in mouse dentate gyrus (DG) was counted. Young (8-week-old) and aged (9-month-old) C57BL/6N mice were intraperitoneally injected with a single dose of bromodeoxyuridine (BrdU) (100 mg/kg) immediately before the stress regimen. Bromodeoxyuridine staining was used to indicate new mitotic cells and doublecortin co-staining was used to reveal early differentiated neural progenitors. Aged mice had lower baselines in the number of newly proliferated cells and neural progenitors compared to young mice regardless of sex. Although young mice were insensitive to the stressor regimen, aged female mice exhibited significant decreases in the number of new cell differentiation and early neurogenesis in response to such stress regimen. The presence of young companions (8-week-old) or aged companions (9-month-old) potentiated the stressor effect by decreasing the basal number of newly cell proliferation or early neurogenesis in aged male mice. These findings suggest that old females may be more sensitive to the modulating effects of stress on early neurogenesis in the dentate gyrus as compared to old males.

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