Distribution of orexinergic neurons and their terminal networks in the brains of two species of African mole rats

Abstract

The distribution of orexinergic cell bodies and terminal networks within the brains of two species of African mole rat (Cape-dune mole rat -Bathyergus suillus and highveld mole rat -Cryptomys hottentotus) were identified using immunohistochemistry for Orexin-A.The aim of the study was to investigate possible differences in the nuclear complement and terminal distribution of this system by comparing those of the mole rats to published studies of other rodents and mammals. The wild-caught mole rats used in this study live a subterranean lifestyle and are well known for their regressed visual system, which may lead to the prediction of differences in the distribution of the cell bodies and the terminal networks; however, we found that both species of mole rat displayed orexinergic nuclei limited to the hypothalamus in regions similar to those previously reported for other rodent and mammalian species. No immunoreactive neurons could be identified, in either species of mole rat within the anterior hypothalamic paraventricular nucleus, as has been reported for Murid rodents. The terminal networks, while remaining similar between the species, are more strongly expressed in the Cape-dune mole rat than in the highveld mole rat.

Orexinergic neuron numbers in three species of African mole rats with rhythmic and arrhythmic chronotypes

“…In all three species of mole rat, orexinergic immunopositive (Orx+) cell bodies were located within the hypothalamus, as previously reported in all mammals studied to date, including mole rats (Bhagwandin et al, 2011a). Stereological counts of Orx+ cell bodies were found to be statistically significantly different only between the distinct circadian chronotypes of Ansel"s mole rat (Fukomys anselli) and between all rhythmic and arrhythmic individuals of the current study when the counts of Orx+ cell bodies were corrected for body mass (M b ).…”

“…All three species of mole rat expressed Orx+ neurons only within the hypothalamus and were observed as sharing common neuronal locality within the lateral hypothalamic area (LHA), perifornical region (PFR) and the lateral ventral hypothalamic supraoptic area (LVHA), similar to those reported in two other species of mole rat (Bhagwandin et al, 2011a). Thus, there appears to be three distinct clusters of Orx+ neurons in the hypothalamus of the mole rats studied, a large homogeneous cluster spanning the lateral and perifornical regions (the main cluster), a distinct cluster extending into the region of the zona incerta (the zona incerta cluster), and a final cluster in the ventral lateral hypothalamus adjacent to the diminutive optic tracts (the optic tract cluster).…”

Nuclear organisation of some immunohistochemically identifiable neural systems in five species of insectivore —Crocidura cyanea, Crocidura olivieri, Sylvisorex ollula, Paraechinus aethiopicus and Atelerix frontalis

“…1, 2). The nomenclature used for the cholinergic nuclei was adopted from Woolf (1991), Limacher et al (2008), Bhagwandin et al (2008), Gravett et al (2009), Pieters et al (2010, and Calvey et al (2013), the catecholaminergic nuclei from Hökfelt et al (1984), Smeets and Gonzalez (2000), Limacher et al (2008), Bhagwandin et al (2008), Gravett et al (2009), Pieters et al (2010 and Calvey et al (2013), the serotonergic nuclei from Törk (1990), Limacher et al (2008), Bhagwandin et al (2008), Gravett et al (2009), Pieters et al (2010 and Calvey et al (2013), and the orexinergic nuclei from Kruger et al (2010b), Bhagwandin et al (2011), Gravett et al (2011 and Calvey et al (2013). …”

Nuclear organization of some immunohistochemically identifiable neural systems in two species of the Euarchontoglires: A Lagomorph, Lepus capensis , and a Scandentia, Tupaia belangeri

“…The nomenclature used for the cholinergic nuclei was adopted from Woolf (1991), Limacher et al (2008, Bhagwandin et al (2008), Gravett et al (2009), Pieters et al (2010), and Calvey et al (2013, the catecholaminergic nuclei from Hökfelt et al (1984), Smeets and Gonzalez (2000), Limacher et al (2008), Bhagwandin et al (2008), Gravett et al (2009), Pieters et al (2010 and Calvey et al (2013), the serotonergic nuclei from Törk (1990), Limacher et al (2008, Bhagwandin et al (2008), Gravett et al (2009), Pieters et al (2010 and Calvey et al (2013), and the orexinergic nuclei from Kruger et al (2010b), Bhagwandin et al (2011), Gravett et al (2011 and Calvey et al (2013). …”