Rocha M Izabel M, Mestriner Regis G, Hermel Erica E S, Xavier Léder L, Rasia-Filho Alberto A, Achaval Matilde
Programa de Pós-graduação em Ciências Biológicas - Fisiologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Neurosci Lett. 2007 Jun 13;420(2):110-5. doi: 10.1016/j.neulet.2007.04.043. Epub 2007 Apr 25.
The posteroventral medial amygdala (MePV) is a brain area where gonadal hormones have neurotrophic effects in rats. The aim of the present study was to estimate the MePV neuronal somatic volume from males and diestrus, proestrus and estrus female Wistar rats (n=5 in each group) in an attempt to identify a possible sexual dimorphism in this parameter. The effect of laterality was also evaluated. The brains of adult animals were sectioned (1 microm), stained with 1% toluidine blue and serial-section reconstructions of each neuronal cell body were obtained. Images from both left and right MePV were studied and the somatic volume was estimated using the Cavalieri method in combination with the point counting technique. Results were compared according to sex and phase of the estrous cycle using a two-way ANOVA for repeated measures followed by the least significance difference test. Mean neuronal somatic volume showed a statistical difference among groups and the post hoc comparisons revealed that males present higher values than females in proestrus and estrus (p<0.05). On the other hand, neither a laterality effect (p=0.6) nor an interaction between groups and laterality (p=0.4) were found. Our results indicate that cell body volume in the MePV is distinct when comparing males to females in the different phases of the estrous cycle. Through dynamic changes modulated by sex steroids, it is likely that this morphological plasticity within the MePV may be affecting the functioning of local neurons and their integrated roles in neural circuits relevant for neuroendocrine control and reproductive behaviors.
杏仁核后腹内侧核（MePV）是性腺激素在大鼠体内具有神经营养作用的脑区。本研究的目的是估计雄性以及处于动情间期、动情前期和动情期的雌性Wistar大鼠（每组n = 5）的MePV神经元体细胞体积，以试图确定该参数中可能存在的性别差异。还评估了脑区偏侧性的影响。对成年动物的大脑进行切片（1微米），用1%甲苯胺蓝染色，并获得每个神经元细胞体的连续切片重建图像。研究了来自左右MePV的图像，并使用卡瓦列里方法结合点计数技术估计体细胞体积。使用重复测量的双向方差分析，随后进行最小显著差异检验，根据性别和动情周期阶段比较结果。平均神经元体细胞体积在各组之间存在统计学差异，事后比较显示，在动情前期和动情期，雄性的值高于雌性（p<0.05）。另一方面，未发现脑区偏侧性效应（p = 0.6），也未发现组间与脑区偏侧性之间的相互作用（p = 0.4）。我们的结果表明，在比较动情周期不同阶段的雄性和雌性时，MePV中的细胞体体积是不同的。通过性类固醇调节的动态变化，MePV内的这种形态可塑性可能会影响局部神经元的功能及其在与神经内分泌控制和生殖行为相关的神经回路中的综合作用。
