Variation of Monoamine Neurotransmitter in Forebrain of Presenilin-1/Presenilin-2 Double Knockout Mice

Conditional forebrain-specific presenilin-1 and presenilin-2 double knockout mice (dKO mice) exhibit several neurodegenerative phenotypes of Alzheimer's disease (AD) pathology, such as tau hyperphosphorylation, neuron loss, forebrain cortical shrinkage and memory impairment. By using capillary electrophoresis assay, monoamine neurotransmitters in forebrain cortex, hippocampus and other forebrain region of dKO mice aged at 6, 9 and 12 months were measured to illustrate the relationship among presenilins function deficiency, neurodegenerative phenotypes and monoamine neurotransmitters. Data showed that levels of monoamine neurotransmitters in forebrain cortex of dKO mice were significantly decreased at 6 months when compared to controls, while as mice getting older, levels of monoamine neurotransmitters increased to that of controls, or even higher. In hippocampus, 5-hydroxytryptamin and epinephrine in dKO mice bad a significant increase at 6 months, followed with a significant increase of each monoamine neurotransmitter at 12 months age. In other forebrain region, 5-hydroxytryptamin and dopamine had a similar level between control and dKO mice at 6 and 9 months but a significant decrease at 12 months; however, level of norepinephrine and epinephrine were significantly decreased at 6 and 12 months except epinephrine of 6 months. These results demonstrated that knockout of presenilins genes could lead to the variation of monoamine neurotransmitters, and the variation profiles were different among forebrain cortex, hippocampus and other forebrain region. However, whether presenilins deficiency caused the variation of monoamine neurotransmitter directly or not, and how about the effects of variation of monoamine neurotransmitters on AD-like pathology need to be further analyzed.