RESUMEN
Ovarian steroids have been suggested to aid in preserving cognitive functioning during aging in both humans and other animals. Spatial memory relies heavily on the hippocampus, a structure that is sensitive to the influence of both ovarian hormones and aging. The present study investigated the outcome of ovarian hormone replacement during aging on performance in a spatial version of the Morris water maze. Female rats were ovariectomized at 14 months of age and received one of three types of replacement prior to testing at 16 months: acute estrogen replacement (2 days), chronic estrogen replacement (28 days), or chronic replacement of both estrogen and progesterone (28 days). Control animals, which did not receive replacement hormones, displayed significant overnight forgetting during acquisition of the task. Ovarian hormone replacement, both acute and chronic, prevented forgetting. Previous studies have demonstrated that high levels of ovarian hormones are detrimental to performance of young adult female rats on this task (Warren and Juraska, 1997; Chesler and Juraska, 2000). The current study found an opposite effect during aging: ovarian hormone replacement was beneficial. This suggests that animal models of menopause, aimed at exploring the protective effects of hormone replacement therapy on cognition during human female aging, require the use of aged female animals.
Asunto(s)
Envejecimiento/psicología , Terapia de Reemplazo de Hormonas , Aprendizaje por Laberinto/efectos de los fármacos , Ovariectomía , Animales , Peso Corporal/efectos de los fármacos , Estrógenos/farmacología , Femenino , Progesterona/farmacología , Ratas , Ratas Long-Evans , NataciónRESUMEN
STAT3 is constitutively phosphorylated on tyrosine(705) in self-renewing, CD5(+) murine B-1 lymphocytes. Nuclear extracts from untreated primary B-1 or CD5(+) BCL(1) B lymphoma cells were found to contain immunoreactive STAT3 protein that binds to a sis-inducible element present in the promoter of the p21(waf1/cip1) tumor suppressor gene and is constitutively phosphorylated on serine(727). To determine the functional significance of constitutive STAT3 activation in B lymphoma cells, a specific STAT3 antisense oligonucleotide was developed and used to examine basal BCL(1) cell growth and IgM production. Abrogating STAT3 expression in BCL(1) cells inhibited their proliferative capacity and induced a corresponding decrease in secretion of IgM. Cell cycle analysis showed a block in progression through G1 in BCL(1) cells treated with the STAT3 antisense oligonucleotide. These results indicate that STAT3 controls cell growth and immunoglobulin secretion by enhancing progression through the G1 phase of the cell cycle in BCL(1) B cell lymphoma.
Asunto(s)
Linfocitos B/fisiología , Ciclo Celular/fisiología , Proteínas de Unión al ADN/fisiología , Inmunoglobulina M/biosíntesis , Transactivadores/fisiología , Animales , Linfocitos B/citología , Linfocitos B/inmunología , División Celular , Células Cultivadas , Inhibidor p21 de las Quinasas Dependientes de la Ciclina , Ciclinas/genética , Expresión Génica , Humanos , Linfoma de Células B , Masculino , Ratones , Ratones Endogámicos BALB C , Peritoneo/citología , Fosforilación , Regiones Promotoras Genéticas , Proteínas Proto-Oncogénicas c-jun/genética , Proteínas Proto-Oncogénicas c-myc/genética , Conejos , Factor de Transcripción STAT3 , Serina/metabolismo , Bazo/citología , Células Tumorales Cultivadas , Tirosina/metabolismoRESUMEN
Previous work reported increases in the number of myelinated axons in the splenium of the rat corpus callosum between 25 and 60 days of age. In the present study, we quantified the area occupied by myelinated axons using a light microscopic point counting technique at 60, 120 and 180 days. Myelinated axons increased across these ages (p=0.001). Thus, myelination of the rat corpus callosum persists well into adulthood.