Sotoudeh Narges, Namavar Mohammad Reza, Bagheri Farshid, Zarifkar Asadollah
Department of Anatomical Sciences, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
Histomorphometry and Stereology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
Brain Behav. 2022 Jul;12(7):e2616. doi: 10.1002/brb3.2616. Epub 2022 May 23.
Aging changes brain function and behavior differently in male and female individuals. Changes in the medial prefrontal cortex (mPFC)-medial amygdala (MeA) connectivity affect anxiety-like behavior.
Therefore, this study aimed to investigate the effect of aging and sex on the mPFC-MeA connection and its association with the level of anxiety-like behavior.
We divided the Wistar rats into the male and female young rats (2-3-month-old) and male and female old rats (18-20 months old). First, the open field test (OFT) was performed, and then 80 nl of Fluoro-Gold (FG) was injected by stereotaxic surgery in the right or left MeA. After 10 days, the animals were perfused, their brain removed, coronal sections cut, and the number of FG-labeled cells in the right and left mPFC of each sample was estimated.
Based on our results, old animals revealed less anxiety-like behavior than young ones, and young females were less anxious than young males, too. Interestingly, MeA of old male rats received more fibers from the bilateral mPFC than young ones. Also, this connection was stronger in the young females than young males. Altogether, the present study indicated that old individuals had less anxiety-like behavior and stronger mPFC-MeA connection, and young female rats were less anxious and had a stronger connection of mPFC-amygdala than males of the same age.
Thus, it seems that there is a negative relationship between anxiety levels based on the rat's performance in the OFT apparatus and the mPFC-MeA connection.
衰老对男性和女性个体大脑功能及行为的影响有所不同。内侧前额叶皮质（mPFC）与内侧杏仁核（MeA）之间的连接变化会影响焦虑样行为。
因此，本研究旨在探究衰老和性别对mPFC - MeA连接的影响及其与焦虑样行为水平的关联。
将Wistar大鼠分为雄性和雌性幼鼠（2 - 3月龄）以及雄性和雌性老年大鼠（18 - 20月龄）。首先进行旷场试验（OFT），然后通过立体定向手术将80 nl荧光金（FG）注射到右侧或左侧MeA。10天后，对动物进行灌注，取出大脑，制作冠状切片，并估计每个样本左右侧mPFC中FG标记细胞的数量。
根据我们的结果，老年动物的焦虑样行为比幼年动物少，幼年雌性比幼年雄性的焦虑程度也更低。有趣的是，老年雄性大鼠的MeA从双侧mPFC接收的纤维比幼年大鼠更多。而且，这种连接在幼年雌性中比幼年雄性更强。总体而言，本研究表明老年个体的焦虑样行为较少且mPFC - MeA连接更强，幼年雌性大鼠比同龄雄性大鼠焦虑程度更低且mPFC - 杏仁核连接更强。
因此，基于大鼠在旷场试验装置中的表现，焦虑水平与mPFC - MeA连接之间似乎存在负相关关系。
