Cell numbers in the dorsal and median raphe nuclei of AS and AS/AGU rats

The AS/AGU rat is a spontaneous recessive mutation derived from a closed colony of Albino Swiss (AS) rats. This mutation generates a stop codon within the coding region of the PKC-gamma gene. The rats exhibit locomotor dysfunction, which is progressive with age. The nigrostriatal system has already been shown to be affected by this mutation that a) there is marked (80-90%) reduction in extracellular dopamine in the dorsal caudateputamen as revealed by in vivo microdialysis and HPLC-ECD and b) there is a loss of tyrosine hydroxylase immunoreactive cells in the substantia nigra pars compacta Because PKC-gamma may be involved in the packaging or release of vesicles, and because other aminergic neurons may also be involved in basal ganglia disorders, we investigated the raphe-striatal serotonergic system in these mutants and the parent AS strain. Animals aged 12-15 months (6 pairs) were killed by administration of sodium pentobarbitone and were perfused with Ringer’s solution + Lignocaine followed by 4% paraformaldehyde. 30 m sections were cut, rostral to caudal, in a one in five series. The collected sections were processed for immunostaining using the Avidin-Biotin-Peroxidase Complex (ABC) technique. All sections of dorsal raphe and median raphe nuclei were counted using the light microscope and also by unbiased Sterological methods using “Stereologer”. In each case, AS/AGU rats possessed an average of 20-25% fewer cells in the dorsal raphe than AS control rats (p<0.05); cell count in the median raphe were unaffected.