L-type calcium channels expressed in the brain are heterogeneous. The predominant class of L-type calcium channels has a Ca_V1.2 pore-forming subunit. L-type calcium channels with a Ca_V1.3 pore-forming subunit are much less abundant, but have been implicated in the generation of mitochondrial oxidant stress underlying pathogenesis in Parkinson's disease. Thus, selectively antagonizing Ca_V1.3 L-type calcium channels could provide a means of diminishing cell loss in Parkinson's disease without producing side effects accompanying general antagonism of L-type calcium channels. However, there are no known selective antagonists of Ca_V1.3 L-type calcium channel. Here we report high-throughput screening of commercial and 'in-house' chemical libraries and modification of promising hits. Pyrimidine-2,4,6-triones were identified as a potential scaffold; structure-activity relationship-based modification of this scaffold led to 1-(3-chlorophenethyl)-3-cyclopentylpyrimidine-2,4,6-(1H,3H,5H)-trione (8), a potent and highly selective Ca_V1.3 L-type calcium channel antagonist. The biological relevance was confirmed by whole-cell patch-clamp electrophysiology. These studies describe the first highly selective Ca_V1.3 L-type calcium channel antagonist and point to a novel therapeutic strategy for Parkinson's disease.

Nitric oxide (NO) is an important signaling molecule in the human body, playing a crucial role in cell and neuronal communication, regulation of blood pressure, and in immune activation. However, overproduction of NO by the neuronal isoform of nitric oxide synthase (nNOS) is one of the fundamental causes underlying neurodegenerative disorders and neuropathic pain. Therefore, developing small molecules for selective inhibition of nNOS over related isoforms (eNOS and iNOS) is therapeutically desirable. The aims of this review focus on the regulation and dysregulation of NO signaling, the role of NO in neurodegeneration and pain, the structure and mechanism of nNOS, and the use of this information to design selective inhibitors of this enzyme. Structure-based drug design, the bioavailability and pharmacokinetics of these inhibitors, and extensive target validation through animal studies are addressed.

Mutations in the GBA1 gene encoding the lysosomal enzyme β-glucocerebrosidase (GCase) represent the most common risk factor for Parkinson’s disease (PD). GCase has been identified as a potential therapeutic target for PD and current efforts are focused on chemical chaperones to translocate mutant GCase into lysosomes. However, for several GBA1-linked forms of PD and PD associated with mutations in LRRK2, DJ-1, and PARKIN, activating wild-type GCase represents an alternative approach. We developed a new small-molecule modulator of GCase called S-181 that increased wild-type GCase activity in iPSC-derived dopaminergic neurons from sporadic PD patients, as well as patients carrying the 84GG mutation in GBA1, or mutations in LRRK2, DJ-1, or PARKIN who had decreased GCase activity. S-181 treatment of these PD iPSC-derived dopaminergic neurons partially restored lysosomal function and lowered accumulation of oxidized dopamine, glucosylceramide and α-synuclein. Moreover, S-181 treatment of mice heterozygous for the D409V GBA1 mutation (Gba1^D409V/+) resulted in activation of wild-type GCase and consequent reduction of GCase lipid substrates and α-synuclein in mouse brain tissue. Our findings point to activation of wild-type GCase by small-molecule modulators as a potential therapeutic approach for treating familial and sporadic forms of PD that exhibit decreased GCase activity.