Increased Number of Neurons in the Cervical Spinal Cord of Aged Female Rats

PORTIANSKY EL; NISHIDA F; BARBEITO CG; GIMENO EJ; GOYA RG

PLOS ONE

PUBLIC LIBRARY SCIENCE

Año: 2011 vol. 6

1932-6203

In the brain, specific signaling pathways localized in highly organized regions called niches allow the persistence of a pool ofstem and progenitor cells that generate new neurons in adulthood. Much less is known about the spinal cord where asustained adult neurogenesis is not observed. Moreover, there is scarce information concerning cell proliferation in theadult mammalian spinal cord and virtually none in aging animals or humans. We performed a comparative morphometricand immunofluorescence study of the entire cervical region (C1-C8) in young (5 mo.) and aged (30 mo.) female rats. Serumprolactin (PRL), a neurogenic hormone, was also measured. Gross anatomy showed a significant age-related increase in sizeof all of the cervical segments. Morphometric analysis of cresyl violet stained segments also showed a significant increase inthe area occupied by the gray matter of some cervical segments of aged rats. The most interesting finding was that boththe total area occupied by neurons and the number of neurons increased significantly with age, the latter increase rangingfrom 16% (C6) to 34% (C2). Taking the total number of cervical neurons the age-related increase ranged from 19% (C6) to51% (C3), C3 being the segment that grew most in length in the aged animals. Some bromodeoxyuridine positive-neuronspecific enolase negative (BrdU+-NSE2) cells were observed and, occasionally, double positive (BrdU+-NSE+) cells weredetected in some cervical segments of both young and aged rats groups. As expected, serum PRL increased markedly withage. We propose that in the cervical spinal cord of female rats, both maturation of pre-existing neuroblasts and/or possibleneurogenesis occur during the entire life span, in a process in which PRL may play a role.