Male Rats Carrying the Taiep Mutation Show Alterations in the Dendritic Arborization of CA1 and CA3 Neurons.

Abstract

The taiep rat originated from a spontaneous mutation in a colony of Sprague-Dawley rats, whose phenotype is inherited as an autosomal recessive trait. The mutant taiep rat shows hypomyelination and demyelination of the central nervous system (CNS) and has been considered a chronic animal model of multiple sclerosis and tubulinopathies. Unlike taiep rats, heterozygous rats for the mutation (+/-), referred to as carriers, have not been widely studied. Thus, the objective of the present study was to examine the dendritic arborization and dendritic spine density of CA1 and CA3 pyramidal neurons of taiep mutation carriers. We evaluated the following groups: Sprague-Dawley rats as a control (SD), mutation carriers (Carrier), and taiep rats (taiep). The brains of the animals were processed using the Golgi-Cox technique to analyze the basilar and apical dendritic arborization and dendritic spine density of CA1 and CA3 pyramidal neurons. We observed a decrease in dendritic arborization in the basilar arbors of dorsal hippocampal CA1 and CA3 pyramidal neurons in both carrier and taiep adult rats, as well as a decrease in dendritic arborization in the apical arbors of CA3 neurons in carrier rats. Moreover, dendritic spine density was reduced in CA1 neurons in both rats. These results show that even when rats are mutation carriers, they exhibit alterations in the dendritic arborization of dorsal hippocampal neurons similar to those of taiep rats.