Aims: 

Ectonucleotidases are transmembrane proteins hydrolyzing ATP necessary for intercellular signaling. Our goal was to map the distribution of ecto-nucleoside triphosphate diphosphohydrolase3 (NTPDase3) in the central nervous system and search for functional correlates using morphological and biochemical techniques.

Methods: 

Antisera were raised against three distinct amino acid sequences of NTPDase3, characterized by Western blot analyses, and used to determine the localization and distribution of NTPDase3 protein in adult rat brain. Several co-localization techniques were utilized to determine the relationship of NTPDase3 to known neuronal systems.

Results: 

NTPDase3-immunoreactivity (IR) was detected exclusively in neurons. IR was localized primarily to neuronal processes with prominent staining of synaptic elements. Specific perikaryal staining predominantly occurred in neurons of the lateral hypothalamus, but scattered immunoreactive neurons were also detected in the perifornical area and the oblongate medulla. High densities of IR axons and dendrites were present in midline regions of the brain and spinal cord. Scattered NTPDase3 positive fiber-like profiles were observed in the cerebral cortex, hippocampus and basal ganglia. High densities of IR punctate structures were detected in the hypothalamus and the molecular layer of the cerebellum. Co-localization studies revealed that in the lateral hypothalamus, NTPDase3 is associated with excitatory morphological profiles of orexin-A immunoreactive neurons, but is absent from GABA-ergic inhibitory systems.

Conclusion: 

In the central nervous system NTPDase3 shows a neuron-specific localization. The pattern of expression and co-localization with hypocretin-1/orexin-A suggests that NTPDase3, by regulating the extracellular turnover of ATP, may modulate neuroendocrine reproductive regulatory mechanisms, feeding, sleep–wake- and other behaviours through diverse homeostatic systems.