School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg, South Africa.
Neuroscience. 2011 Dec 29;199:153-65. doi: 10.1016/j.neuroscience.2011.10.023. Epub 2011 Oct 20.
In the present study, orexinergic cell bodies within the brains of rhythmic and arrhythmic circadian chronotypes from three species of African mole rat (Highveld mole rat-Cryptomys hottentotus pretoriae, Ansell's mole rat--Fukomys anselli and the Damaraland mole rat--Fukomys damarensis) were identified using immunohistochemistry for orexin-A. Immunopositive orexinergic (Orx+) cell bodies were stereologically assessed and absolute numbers of orexinergic cell bodies were determined for the distinct circadian chronotypes of each species of mole rat examined. The aim of the study was to investigate whether the absolute numbers of identified orexinergic neurons differs between distinct circadian chronotypes with the hypothesis of elevated hypothalamic orexinergic neurons in the arrhythmic chronotypes compared with the rhythmic chronotypes. We found statistically significant differences between the circadian chronotypes ofF. anselli, where the arrhythmic group had higher mean numbers of hypothalamic orexin neurons compared with the rhythmic group. These differences were observed when the raw data was compared and when the raw data was corrected for body mass (M(b)) and brain mass (M(br)). For the two other species investigated, no significant differences were noted between the chronotypes, although a statistically significant difference was noted between all rhythmic and arrhythmic individuals of the current study when the counts of orexin neurons were corrected for M(b)--the arrhythmic individuals had larger numbers of orexin cells.
在本研究中，使用 Orexin-A 的免疫组织化学方法鉴定了三种非洲鼹鼠（Highveld 鼹鼠-Cryptomys hottentotus pretoriae、Ansell 的鼹鼠-Fukomys anselli 和 Damaraland 鼹鼠-Fukomys damarensis）的节律和非节律昼夜型的脑内 Orexin 能细胞体。对免疫阳性的 Orexin 能（Orx+）细胞体进行了立体学评估，并确定了每种鼹鼠的不同昼夜型的 Orexin 能细胞体的绝对数量。该研究的目的是调查不同昼夜型的 Orexin 能神经元的绝对数量是否存在差异，假设非节律型昼夜型的下丘脑 Orexin 能神经元数量高于节律型昼夜型。我们发现，F. anselli 的昼夜型之间存在统计学上的显著差异，其中非节律组的下丘脑 Orexin 神经元数量明显高于节律组。当比较原始数据和对体重（M(b)）和脑重（M(br)）进行校正时，都观察到了这些差异。对于另外两种被调查的物种，昼夜型之间没有观察到显著差异，尽管当对 Orexin 神经元的计数进行 M(b)校正时，当前研究中的所有节律和非节律个体之间都存在统计学上的显著差异，即非节律个体的 Orexin 细胞数量更多。
