Novel changes in gene expression following axotomy of a sympathetic ganglion: A microarray analysis

Abstract

Neurons of the peripheral nervous system are capable of extensive regeneration following axonal injury. This regenerative response is accompanied by changes in gene expression in axotomized neurons and associated nonneuronal cells. In the sympathetic nervous system, a few of the genes affected by axonal injury have been identified; however, a broad sampling of genes that could reveal additional and unexpected changes in expression has been lacking. We have used DNA microarray technology to study changes in gene expression within 48 h of transecting the postganglionic trunks of the adult rat superior cervical ganglion (SCG). The expression of more than 200 known genes changed in the ganglion, most of these being genes not previously associated with the response to injury. In contrast, only 10 genes changed following transection of the preganglionic cervical sympathetic trunk. Real-time RT-PCR analysis verified the upregulation of a number of the axotomy-induced genes, including activating transcription factor-3 (ATF-3), arginase I (arg I), cardiac ankyrin repeat protein, galanin, osteopontin, pituitary adenylate cyclase-activating polypeptide (PACAP), parathyroid hormone-related peptide, and UDP-glucoronosyltransferase. Arg I mRNA and protein were shown to increase within neurons of the axotomized SCG. Furthermore, increases in the levels of putrescine and spermidine, a diamine and polyamine produced downstream of arg I activity, were also detected in the axotomized SCG. Our results identified many candidate genes to be studied in the context of peripheral nerve regeneration. In addition, the data suggest a potential role for putrescine and spermidine, acting downstream of arg I, in the regenerative process.

Regulation of neuronal pituitary adenylate cyclase-activating polypeptide expression during culture of guinea-pig cardiac ganglia

“…However, PACAP expression increases markedly in these neurons following axotomy or explant culture (Zhang et al, 1995(Zhang et al, ,1996Moller et al, 1997a,b;Zhou et al, 1999;Pettersson et al, 2004). It is hypothesized that the increased expression of PACAP may be a response to injury that supports cell survival and regeneration (Moller et al, 1997a,b;Armstrong et al, 2003;Boeshore et al, 2004;Pettersson et al, 2004;Suarez et al, 2006).…”

“…In rat SCG neurons, one key mechanism stimulating a change in transmitter phenotype in ganglia explants or after axotomy is the production and secretion of a regulatory factor, leukemia inhibitory factor (LIF), by non-neural cells (Sun et al, 1994;Lewis et al, 1994;Sun and Zigmond, 1996;Cheng et al, 1997;Boeshore et al, 2004). Consequently, we tested, using an immunocytochemical assay, whether members of a number of common regulatory factor and/or target-derived factor families enhanced PACAP expression.…”

“…Thus, in the case of CARTp, neurturin normally inhibits CARTp expression, but during culture the loss of neurturin releases this inhibition. In contrast for PACAP, the loss of neurturin appeared to be only one of a number of mechanisms regulating its expression as PACAP expression continued to increase, albeit at a lower level, even when neurturin was present in the culture media.In the rat SCG, synthesis and secretion of LIF by non-neuronal cells after axotomy or during explant culture is thought to be an important stimulator of neuropeptide expression (Sun et al, 1994;Lewis et al, 1994;Sun and Zigmond, 1996;Cheng et al, 1997;Boeshore et al, 2004). We postulated that a similar mechanism might contribute to the stimulation of PACAP expression in cultured cardiac neurons.…”

“…However, PACAP expression increases markedly in these neurons following axotomy or explant culture (Zhang et al, 1995(Zhang et al, ,1996Moller et al, 1997a,b;Zhou et al, 1999;Pettersson et al, 2004). It is hypothesized that the increased expression of PACAP may be a response to injury that supports cell survival and regeneration (Moller et al, 1997a,b;Armstrong et al, 2003;Boeshore et al, 2004;Pettersson et al, 2004;Suarez et al, 2006).In acutely isolated guinea pig cardiac ganglia, all the intrinsic neurons are innervated by extrinsic PACAP-IR fibers, but very few of the cardiac neurons exhibit PACAP immunoreactivity Calupca et al, 2000;Parsons et al, 2006). Following explant culture, the extrinsic PACAP-IR fibers degenerate and the percentage of cholinergic neurons expressing PACAP increases significantly (Calupca et al, 2000;Girard et al, 2006b).…”

Activating transcription factor 3 immunoreactivity identifies small populations of axotomized neurons in rat cervical sympathetic ganglia after transection of the preganglionic cervical sympathetic trunk

“…Tsujino and colleagues (2000) identified activating transcription factor 3 (ATF3) as a gene that is expressed in both sensory and motor neurons after sciatic nerve injury while being undetectable in these same neurons in the intact animal. Similarly, we have recently found that, while ATF3 is not normally expressed in sympathetic neurons in the superior cervical ganglion (SCG), it is expressed in these neurons after transection of the postganglionic internal and external carotid nerves (Boeshore et al, 2004;Hyatt-Sachs, Schreiber, Shoemaker, Sabe, Reed, and Zigmond submitted). While ATF3 has been proposed as a marker for injured neurons (Tsujino et al, 2000), in a study on the corticospinal tract after axotomy, Mason et al (2003) found that the expression of ATF3 increased following a proximal lesion (i.e., a lesion 350-500 μm from the cell soma), but not following a more distal lesion.…”