ABSTRACT
Adult rats were treated acutely with peripheral kainic acid (KA), and changes in brain-derived neurotrophic factor (BDNF) mRNA and protein were tracked over time across multiple brain regions. Despite robust elevation in both mRNA and protein in multiple brain regions, plasma BDNF was unchanged and cerebrospinal fluid (CSF) BDNF levels remained undetectable. Primary neurons were then treated with KA. BDNF was similarly elevated within neurons, but was undetectable in neuronal media. Thus, while deficits in BDNF signaling have been implicated in a number of diseases, these data suggest that extracellular concentrations of BDNF may not be a facile biomarker for changes in neurons.
Subject(s)
Brain-Derived Neurotrophic Factor/blood , Brain-Derived Neurotrophic Factor/genetics , Gene Expression , Hippocampus/metabolism , Animals , Brain/metabolism , Brain/pathology , Brain-Derived Neurotrophic Factor/cerebrospinal fluid , Brain-Derived Neurotrophic Factor/metabolism , Cells, Cultured , Choroid Plexus/pathology , Hippocampus/pathology , Humans , Kainic Acid , L-Lactate Dehydrogenase/metabolism , Male , Neurons/enzymology , Neurons/metabolism , Primary Cell Culture , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley , Seizures/blood , Seizures/cerebrospinal fluid , Seizures/chemically inducedABSTRACT
Phosphodiesterases (PDEs) comprise a family of enzymes that regulate the levels of cyclic nucleotides, key second messengers that mediate a diverse array of functions. PDE2A is an evolutionarily conserved cGMP-stimulated cAMP and cGMP PDE. In the present study, the regional and cellular distribution of PDE2A in tissues of rats, mice, cynomolgus monkeys, dogs, and humans was evaluated by immunohistochemistry. A polyclonal antibody directed to the C-terminal portion of PDE2A specifically detected PDE2A by Western blotting and by immunohistochemistry. The pattern of PDE2A immunoreactivity (ir) was consistent across all species. Western blot analysis demonstrated that PDE2A was most abundant in the brain relative to peripheral tissues. PDE2A ir was heterogeneously distributed within brain and was selectively expressed in particular peripheral tissues. In the brain, prominent immunoreactivity was apparent in components of the limbic system, including the isocortex, hippocampus, amygdala, habenula, basal ganglia, and interpeduncular nucleus. Cytoplasmic PDE2A staining was prominent in several peripheral tissues, including the adrenal zona glomerulosa, neurons of enteric ganglia, endothelial cells in all organs, lymphocytes of spleen and lymph nodes, and pituitary. These studies suggest that PDE2A is evolutionarily conserved across mammalian species and support the hypothesis that the enzyme plays a fundamental role in signal transduction.
Subject(s)
Cyclic Nucleotide Phosphodiesterases, Type 2/biosynthesis , Animals , Blotting, Western , Brain/anatomy & histology , Brain/enzymology , Cyclic Nucleotide Phosphodiesterases, Type 2/genetics , Dogs , Ganglia, Spinal/anatomy & histology , Ganglia, Spinal/enzymology , Humans , Immunohistochemistry , In Situ Hybridization , Macaca fascicularis , Mice , Mice, Knockout , Organ Specificity , Rats , Rats, Sprague-Dawley , Species Specificity , Spinal Cord/anatomy & histology , Spinal Cord/enzymologyABSTRACT
A monoclonal antibody directed against the amino terminal of rat phosphodiesterase 10A (PDE10A) was used to localize PDE10A in multiple central nervous system (CNS) and peripheral tissues from mouse, rat, dog, cynomolgus macaque, and human. PDE10A immunoreactivity is strongly expressed in the CNS of these species with limited expression in peripheral tissues. Within the brain, strong immunoreactivity is present in both neuronal cell bodies and neuropil of the striatum, in striatonigral and striatopallidal white matter tracks, and in the substantia nigra and globus pallidus. Outside the brain, PDE10A immunoreactivity is less intense, and distribution is limited to few tissues such as the testis, epididymal sperm, and enteric ganglia. These data demonstrate that PDE10A is an evolutionarily conserved phosphodiesterase highly expressed in the brain but with restricted distribution in the periphery in multiple mammalian species.
