Purkinje Cell Survival and Axonal Regeneration Are Age Dependent: AnIn VitroStudy

Abstract

Purkinje cells are among the most resistant neurons to axotomy and the most refractory to axonal regeneration. By using organotypic cultures, we have studied age-and environmentrelated factors implicated in Purkinje cell survival and axonal regeneration. Most Purkinje cells taken from 1-to 5-d-old rats, the period in which these neurons are engaged in intense synaptogenesis and dendritic remodeling, die 1 week after plating, whereas if cultured before or after this period, Purkinje cells survive, even in the absence of deep nuclear neurons, their postsynaptic targets. Cerebellar slices taken from 10-dold rats and kept in vitro for 1 week acquire a cellular composition resembling mature cerebellum. Their Purkinje cells are resistant to axotomy, but even when confronted with permissive environments (sciatic nerves or fetal cerebellar slices), their axons do not regenerate. In contrast, fetal rat and mouse Purkinje cells are able to regenerate their axons on mature cerebellar slices. This regeneration is massive, and the regrowing axons invade all cerebellar regions of the apposed mature slices, including white matter. These results show that Purkinje cell survival and axonal regeneration are age-related and independent from environmental constraints. Moreover, our observations suggest strongly that the onset of synaptogenesis of Purkinje cell axons could provide a signal to turn off their growth program and that, thereafter, permissive microenvironment alone is unable to reestablish such a program. Key words: axonal regeneration; neuronal survival; cerebellum; Purkinje cell maturation; cerebellar organotypic cultures; axonal growthMost adult neurons survive axotomy if the lesion occurs far from their cell bodies, whereas perinatal neurons often die even after far-away axotomy (for review, see Schwab and Bartholdi, 1996). Frequently, this perinatal cell death can be counteracted by neurotrophic factors or by embryonic tissue grafting (for review, see Schwab and Bartholdi, 1996). In addition, immature CNS neurons have a higher potential to regenerate their axons than adult CNS neurons (for review, see Schwab and Bartholdi, 1996). Nevertheless, if allowed to regrow into transplanted peripheral nerves, most adult CNS cut axons regenerate their lesioned processes (David and Aguayo, 1981;Aguayo, 1985). Furthermore, the application of blocking antibodies against CNS myelin inhibitory proteins favors regeneration of axotomized corticospinal axons after spinal cord injury (Schnell and Schwab, 1990;Schwab et al., 1993). These observations strongly support the hypothesis that environmental factors rather than the intrinsic inability of adult CNS axons to regenerate are the limiting factor in the failure of axonal regeneration.Adult Purkinje cells are among the most resistant neurons to axotomy and the most refractory to axonal regeneration: they do not regenerate their axons even in the presence of their embryonic targets (Rossi et al., 1995). These cells in addition are one of the rare categories of neurons whose axons hav...

Degradation of Chondroitin Sulfate Proteoglycans Induces Sprouting of Intact Purkinje Axons in the Cerebellum of the Adult Rat

“…Despite their poor regenerative potential (Rossi et al, 1995b;Dusart et al, 1997;Carulli et al, 2004), Purkinje axons are capable of extensive sprouting at long-term after injury (Dusart and Sotelo, 1994;Dusart et al, 1999;Gianola and Rossi, 2002), when the scar environment acquires growth-promoting/permissive properties, including disappearance of CSPGs (Dusart et al, 1999(Dusart et al, , 2005Morel et al, 2002). In addition, similar to other systems (Thallmair et al, 1998;Bareyre et al, 2002), sprouting from intact Purkinje axons, with aberrant growth into the deep granular layer, can be induced by application of anti-Nogo antibodies in both adult (Buffo et al, 2000) and developing (Gianola et al, 2003) cerebella.…”

SCLIP Is Crucial for the Formation and Development of the Purkinje Cell Dendritic Arbor

“…Briefly, fusiform PCs with a bipolar shape were defined as stage 1, stellate PCs with processes all around the soma as stage 2, PCs with several long and mature perisomatic dendritic processes as stage 3, and PCs with a single dendritic tree giving rise to additional side branches as stage 4. It should be noted that stage 3 with the presence of more than one primary dendritic tree is specific of organotypic cultures (Dusart et al, 1997;Kapfhammer, 2004) and appears in parallel with stage 4. For each experiment, at least 100 transduced PCs from all slices were quantified.…”

“…Numerous branches and spines were detected at these two stages, which correspond to mature PCs and occur in parallel. In vivo, only stage 4 is observed, the presence of stage 3 cells with multipolar primary dendritic processes being attributable to the organotypic culture conditions (Dusart et al, 1997;Kapfhammer, 2004).…”

Rorα, a pivotal nuclear receptor for Purkinje neuron survival and differentiation: From development to ageing

“…However, further studies will be needed to determine whether the observed Purkinje cell loss is linked to an increased ROS production in Rora +/sg mutants. Furthermore, many studies have proposed the existence of a developmental Purkinje cell death period, occurring around P3 (52)(53)(54)(55)(56). Interestingly, in Rora sg/sg mice, Purkinje cell loss seems to occur during this period (32).…”