Comparative anatomy of the distribution of catecholamines within the inferior olivary complex from teleosts to primates

Abstract

The distribution of catecholamine (CA) in the inferior olivary complex (IO) of various vertebrate (from fish to monkey) was investigated by means of the histofluorescence technique. In addition, using rats, a further attempt was made to elucidate the origins of CA in the IO. The IO of the lower vertebrates (from fish to birds) was in general poorly innervated by the CA neuron system. IO in the lower mammals, such as insectivora and bats, contained only a few CA nerve terminals, while that in the higher mammals such as rat, guinea pig, rabbit, cat, and monkey revealed quite a number. In these animals, species-species patterns of CA nerve terminals were found. In the rat, the highest concentration was observed in the dorsal lamella of the principal nucleus and in guinea pig ventral lamella. In the rabbit and cat, maximum CA nerve terminals were detected in the dorsal accessory nucleus, while in the monkey, they were detected in the medial accessory nucleus. The retrograde tracer technique of horseradish peroxidase (HRP) suggested that the main source of the abundant CA terminals in IO of the rat might be A1, A2, and A3 noradrenaline neurons, though not locus coeruleus and not dopaminergic ones.

Inferior Olive: All Ins and Outs

“…In the rat, the VLO, known to be involved in compensatory eye movements, is targeted by dopaminergic projections from the mesodiencephalic junction (Toonen et al 1998). Again, this can differ between species: In the cat, dopaminergic nerve terminals are most prominent in the DAO (Maqbool et al 1993) whereas catecholaminergic fibers are mostly seen in the MAO and lateral lamella of the PO in the monkey (Sladek and Bowman 1975;Kamei et al 1981). Interestingly, the noradrenaline fibers in the IO are much more homogeneously distributed in humans than in rat, cat, and monkey (Powers et al 1990).…”

Locus Coeruleus in Non-Mammalian Vertebrates

“…The above studies show conserved projections of the LC among vertebrates. However, these projections have been mapped at the populational level by anterograde/retrograde dye tracing [ 32 , 37 , 41 , 44 , 45 , 59 , 60 , 61 ], or immunostaining [ 13 , 62 , 63 , 64 ]. Next, a single-cell level wiring diagram will be important.…”

Inferior Olive: All Ins and Outs

“…In rat, the dopaminergic projections from the mesodiencephalic junction target the VLO, which is involved in vertical compensatory eye movements (Toonen et al 1998), whereas in cat, the dopaminergic nerve terminals are most prominent in the DAO, which may be involved in sensorimotor processing during locomotion (Horn et al 2010(Horn et al , 2013Maqbool et al 1993). And again, differently, in nonhuman primates, catecholaminergic fibers are mostly seen in the MAO and lateral lamella of the PO (Kamei et al 1981;Sladek and Bowman 1975), whereas in humans the noradrenergic fibers in the IO are much more homogeneously distributed than in rat, cat, and monkey (Powers et al 1990).…”