Abstract
Phenylethanolamine N-methyltransferase (Pnmt) catalyzes the N-methylation of norepinephrine to produce epinephrine, a potent stress hormone and neurotransmitter. Most of our knowledge about Pnmt is derived from its role in systemic production of epinephrine from adrenal chromaffin cells, but it is also known to be expressed in the central nervous system, including brainstem, retina, hypothalamus, and cerebellum. Of these regions, the cerebellum has been the least well-characterized with respect to Pnmt expression. Given the importance of the cerebellum for motor control and coordination, we sought to investigate cellular Pnmt expression in the cerebellum using a genetic-marking strategy with a Pnmt-Cre-recombinase knock-in driver strain (Pnmt+/Cre) and a β-galactosidase (βGal) reporter strain (R26R+/βGal) in parallel with Pnmt-specific immunofluorescent histochemical staining to identify Pnmt+ cells in sections of adult mouse cerebellum. Our results show active Pnmt protein expression in Purkinje neuron soma throughout the cerebellum, as demonstrated by positive Pnmt immunofluorescence and βGal expression. In contrast, the granular layer (GL) and Deep Cerebellar Nuclei (DCN) showed apparent historical expression with strong βGal expression in the absence of positive Pnmt immunofluorescence. These results suggest Pnmt+ cells may contribute more substantially to the cerebellum than previously appreciated and provide anatomical “blueprints” for investigating the role of cerebellar Pnmt expression in health and disease.