Combination of gonadal steroid treatment and peripheral nerve grafting results in a peripheral motoneuron-like pattern of beta II-tubulin mRNA expression in axotomized hamster rubrospinal motoneurons.
Rubrospinal motoneurons (RSMN) represent a population of androgen receptor-containing central motoneurons in rodents. In this study, the ability of testosterone propionate (TP), alone or in conjunction with a peripheral nerve graft (PNG), to alter the molecular program of injured RSMN was accomplished using betaII-tubulin cDNA probes and quantitative in situ hybridization (ISH). Initial fluoro-gold labeling experiments following a T1 hemisection established that, as in the rat, the hamster rubrospinal system is essentially crossed and that injured RSMN concentrate in the ventrolateral region of the red nucleus. In the second experimental series, adult gonadectomized male hamsters were subjected to a right T1 hemisection, with half of the operated animals immediately subcutaneously implanted with 1 10 mm TP Silastic capsule and the other half sham implanted. In a third experimental series, animals were subjected to T1 hemisection, followed by transplantation of a predegenerated autologous segment of peripheral nerve. Half of the animals in each group received TP implants at the time of spinal cord injury and PNG. Postoperative times were 2, 7, and 14 days (dpo). Quantitative ISH was performed using a betaII-tubulin-specific (33)P-labeled cDNA probe, emulsion autoradiography, and computerized image analysis for grain counting. Injury alone resulted in a short-lived increase in betaII-tubulin mRNA expression in the RSMN at 2 dpo, with a significant decline to well below control values at 7 and 14 dpo. TP treatment or PNG alone attenuated, but did not prevent, the down-regulation of betaII-tubulin mRNA. In contrast, the combination of TP with a PNG sustained the injury-induced increase in betaII-tubulin mRNA levels throughout the postoperative period of 2, 7, and 14 dpo. The synergistic effects of the two treatment strategies confirm the importance of targeting multiple aspects of the injury response for therapeutic intervention.
Storer
Paul D
PD
Department of Cell Biology, Neurobiology, and Anatomy, Loyola University-Chicago, Maywood, IL 60153, USA. storerpauld@uams.edu
Houle
John D
JD
Oblinger
Monica
M
Jones
Kathryn J
KJ
D000818:Animals; D019771:Axotomy / Q000379:methods; D006224:Cricetinae; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D012739:Gonadal Steroid Hormones / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D008647:Mesocricetus; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism*; D010525:Peripheral Nerves / Q000378:metabolism / Q000637:transplantation*; D010543:Peroneal Nerve / Q000378:metabolism / Q000637:transplantation; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis*; D012012:Red Nucleus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000188:drug therapy / Q000378:metabolism / Q000601:surgery; D013739:Testosterone / Q000494:pharmacology* / Q000627:therapeutic use; D016378:Tissue Transplantation / Q000379:methods; D014404:Tubulin / Q000096:biosynthesis* / Q000235:genetics
D012739:Gonadal Steroid Hormones; D020033:Protein Isoforms; D012333:RNA, Messenger; D014404:Tubulin; D013739:Testosterone