The superior colliculus of the camel: a neuronal‐specific nuclear protein (NeuN) and neuropeptide study

Abstract

In this study we examined the superior colliculus of the midbrain of the one-humped (dromedary) camel, Camelus dromedarius , using Nissl staining and anti-neuronal-specific nuclear protein (NeuN) immunohistochemistry for total neuronal population as well as for the enkephalins, somatostatin (SOM) and substance P (SP). It was found that, unlike in most mammals, the superior colliculus is much larger than the inferior colliculus. The superior colliculus is concerned with visual reflexes and the co-ordination of head, neck and eye movements, which are certainly of importance to this animal with large eyes, head and neck, and apparently good vision. The basic neuronal architecture and lamination of the superior colliculus are similar to that in other mammals. However, we describe for the first time an unusually large content of neurons in the superior colliculus with strong immunoreactivity for met-enkephalin, an endogenous opioid. We classified the majority of these neurons as small (perimeters of 40-50 µ m), and localized diffusely throughout the superficial grey and stratum opticum. In addition, large pyramidal- immunopositive to SOM and SP were located exclusively in the superficial grey layer. We propose that this system may be associated with a pain-inhibiting pathway that has been described from the periaqueductal grey matter, juxtaposing the deep layers of the superior colliculus, to the lower brainstem and spinal cord. Such pain inhibition could be important in relation to the camel's life in the harsh environment of its native deserts, often living in very high temperatures with no shade and a diet consisting largely of thorny branches.

Broad characterization of endogenous peptides in the tree shrew visual system

“…Although we did not do so here, MS methods can in principle also be used to study peptide distribution across cortical layers. Also consistent with our results are previous reports of Enkephalines in the superior colliculus [58]. While Enkephalins have been mostly associated with addiction and pain, our studies suggest that they may also play an important role in maintaining the function of the visual system.…”

Histology and Brain Derived Neurotrophic Factor immunoreaction of the neurons in the corpora quadrigemina of the African grasscutter (Thryonomys swinderianus – Temminck, 1827)

“…Conversely, Telford et al (1996) reported that the stratum griseum of Sprague-Dawley rats is further divided into stratum griseum superficiale, stratum opticum, stratum griseum intermediale, stratum album intermediale and stratum griseum profundum, suggesting a good eyesight. Similarly, Mensah-Brown and Garey (2006) recorded six laminae in the rostral colliculus of camels. They also concluded that visual system of the camel is well developed suggesting a good eyesight in the camel.…”

“…It is composed of a pair of rostral and a pair of caudal colliculi. The rostral colliculus is the visual reflex centre, concerned with the co-ordination of reflexive movements of the head, neck and eyes, as well as focusing of the lens and visual tracking of objects (Mensah-Brown and Garey, 2006;Walton et al, 2007). The caudal colliculus is the acoustic reflex centre.…”

Widespread immunoreactivity for neuronal nuclei in cultured human and rodent astrocytes

“…1992; Stamatakis et al. 2004; Mensah‐Brown and Garey 2006). NeuN immunoreactivity has also been described in human primary brain tumors and neuronal‐cell lines (Mullen et al.…”