An updated investigation on the dromedary camel cerebellum (Camelus dromedarius) with special insight into the distribution of calcium-binding proteins

Abstract

Studying the cerebella of different animals is important to expand the knowledge about the cerebellum. Studying the camel cerebellum was neglected even though the recent research in the middle east and Asia. Therefore, the present study was designed to achieve a detailed description of the morphology and the cellular organization of the camel cerebellum. Because of the high importance of the calcium ions as a necessary moderator the current work also aimed to investigate the distribution of calcium binding proteins (CaBP) such as calbindin D-28K (CB), parvalbumin (PV) and calretinin (CR) in different cerebellar cells including the non-traditional neurons. The architecture of camel cerebellum, as different mammals, consists of the medulla and three layered-cortex. According to our observation the cells in the granular layer were not crowded and many spaces were observed. CB expression was the highest by Purkinje cells including their dendritic arborization. In addition to its expression by the inhibitory interneurons (basket, stellate and Golgi neurons), it is also expressed by the excitatory granule cells. PV was expressed by Purkinje cells, including their primary arborization, and by the molecular layer cells. CR immunoreactivity (-ir) was obvious in almost all cell layers with varying degrees, however a weak or any expression by the Purkinje cells. The molecular layer cells and the Golgi and the non traditional large neurons of the granular layer showed the strongest CR-ir. Granule neurons showed moderate immunoreactivity for CB and CR. In conclusion, the results of the current study achieved a complete map for the neurochemical organization of CaBP expression and distribution by different cells in the camel cerebellum.

A Golgi study of neurons in the camel cerebellum (Camelus dromedarius)

“…This suggests that these cells exerted a finer inhibitory control over the Purkinje cells. This is in line with the immunohistochemical findings, where the somata of both stellate and basket cells are intensely stained for parvalbumin and calretinin (Attaai et al, 2020;Maseko et al, 2013). This may give camels a better ability to coordinate their motor activity and balance, which is required because of its large size and ability to perform highly coordinated functions (carrying heavy loads while walking).…”

“…The other two cell types, Lugaro and unipolar brush cells, were less impregnated. Nevertheless, these latter cells have been described in a previous study using crystal violet and immunohistochemical staining (Attaai et al, 2020). The teleostean, amphibian, reptilian, and avian cerebella have similar granule and Golgi cells in the granular layer of their cerebella (Cajal, 2000; Larsell, 1932; Nieuwenhuys, 1967).…”

“…Similar to our observations in camels, Purkinje cells in birds and mammals become regularly arranged in a single layer throughout the cerebellum with extensive dendritic arborization spreading in the molecular layer confined to the sagittal plane (Jacobs et al, 2014; Nieuwenhuys, 1967). Immunohistochemically, it has been shown that somata, dendrites, and axons of Purkinje cells in camels are positive for calbindin and, to a lesser extent, parvalbumin (Attaai et al, 2020).…”

“…When walking, camels move the 2 ft. of one side of their body together, followed by the 2 ft. of the other side. Descriptions of the gross morphology, cellular neurochemical organization, and arterial vascular architecture in camels have been thoroughly investigated by various research groups (Al Aiyan et al, 2019; Attaai, Noreldin, Abdel‐Maksoud, & Hussein, 2020; Ghaji, 1985). Herein, we investigated the neuronal morphology and several quantitative parameters of different types of neurons in the cerebellar cortex of camels and compared these neurons with their counterparts in other species.…”

Programmed cell death in cerebellar Purkinje neurons

“…Furthermore, Ca 2+ -binding proteins, which buffer the Ca 2+ in the cell by binding to it, also participate in maintaining [Ca 2+ ] i that are essential for normal Ca 2+ signaling, and thus preventing the accumulation of pathologic quantities of Ca 2+ [138,[143][144][145].…”