Downregulation of PACAP and the PAC1 Receptor in the Basal Ganglia, Substantia Nigra and Centrally Projecting Edinger-Westphal Nucleus in the Rotenone model of Parkinson's Disease.

Numerous in vitro and in vivo models of Parkinson's disease (PD) demonstrate that pituitary adenylate cyclase-activating polypeptide (PACAP) conveys its strong neuroprotective actions mainly via its specific PAC1 receptor (PAC1R) in models of PD. We recently described the decrease in PAC1R protein content in the basal ganglia of macaques in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD that was partially reversed by levodopa therapy. In this work, we tested whether these observations occur also in the rotenone model of PD in the rat. The rotarod test revealed motor skill deterioration upon rotenone administration, which was reversed by benserazide/levodopa (B/L) treatment. The sucrose preference test suggested increased depression level while the open field test showed increased anxiety in rats rendered parkinsonian, regardless of the received B/L therapy. Reduced dopaminergic cell count in the substantia nigra pars compacta (SNpc) diminished the dopaminergic fiber density in the caudate-putamen (CPu) and decreased the peptidergic cell count in the centrally projecting Edinger-Westphal nucleus (EWcp), supporting the efficacy of rotenone treatment. RNAscope in situ hybridization revealed decreased PACAP mRNA (Adcyap1) and PAC1R mRNA (Adcyap1r1) expression in the CPu, globus pallidus, dopaminergic SNpc and peptidergic EWcp of rotenone-treated rats, but no remarkable downregulation occurred in the insular cortex. In the entopeduncular nucleus, only the Adcyap1r1 mRNA was downregulated in parkinsonian animals. B/L therapy attenuated the downregulation of Adcyap1 in the CPu only. Our current results further support the evolutionarily conserved role of the PACAP/PAC1R system in neuroprotection and its recruitment in the development/progression of neurodegenerative states such as PD.

Endovascular Recanalization of Tandem Internal Carotid Occlusions Using the Balloon-assisted Tracking Technique.

PURPOSE: Tandem occlusive lesions are responsible for up to 20% of acute ischemic stroke cases and are associated with poor prognosis if complete recanalization cannot be achieved. Endovascular recanalization might be challenging due to difficulties in the safe passage of the occluded plaque at the origin of the internal carotid artery (ICA). The balloon-assisted tracking technique (BAT), where a partially deflated balloon is exposed out of the catheter tip to facilitate its passage through stenosed or spastic arterial segments was introduced by interventional cardiologists and the applicability of the technique has been recently proposed in the field of neurointervention as well. Here we describe our experience using the BAT technique in the endovascular recanalization of tandem occlusive lesions. METHODS: Procedures were performed from June 2013 to December 2020 in a single center. Baseline clinical and imaging data, procedural and follow-up details and clinical outcomes were retrospectively collected. RESULTS: In this study 107 patients, median age 66 years, median admission NIHSS 14 and median ASPECTS 8 were included. Successful recanalization of the ICA using the BAT technique was achieved in 100 (93%) and successful intracranial revascularization in 88 (82%) patients. There were no complications attributable to the BAT technique. Intraprocedural complications occurred in 9 (8%) patients. Emergent stenting was performed in 40 (37%) at the end of the procedure. Postprocedural adverse events (intracerebral hemorrhage [ICH], malignant infarction) occurred in 6 (5%) patients. Good clinical outcome at 3 months (modified Rankin scale [mRS] 0-2) was 54 (50%) and mortality 26 (24%). Delayed stent placement during follow-up occurred in 21 cases. CONCLUSION: Application of BAT technique in tandem occlusions appears feasible, safe, and efficient. Further evaluation of this technique is awaited.

Characterization of Neurons Expressing the Novel Analgesic Drug Target Somatostatin Receptor 4 in Mouse and Human Brains.

Somatostatin is an important mood and pain-regulating neuropeptide, which exerts analgesic, anti-inflammatory, and antidepressant effects via its Gi protein-coupled receptor subtype 4 (SST4) without endocrine actions. SST4 is suggested to be a unique novel drug target for chronic neuropathic pain, and depression, as a common comorbidity. However, its neuronal expression and cellular mechanism are poorly understood. Therefore, our goals were (i) to elucidate the expression pattern of Sstr4/SSTR4 mRNA, (ii) to characterize neurochemically, and (iii) electrophysiologically the Sstr4/SSTR4-expressing neuronal populations in the mouse and human brains. Here, we describe SST4 expression pattern in the nuclei of the mouse nociceptive and anti-nociceptive pathways as well as in human brain regions, and provide neurochemical and electrophysiological characterization of the SST4-expressing neurons. Intense or moderate SST4 expression was demonstrated predominantly in glutamatergic neurons in the major components of the pain matrix mostly also involved in mood regulation. The SST4 agonist J-2156 significantly decreased the firing rate of layer V pyramidal neurons by augmenting the depolarization-activated, non-inactivating K+ current (M-current) leading to remarkable inhibition. These are the first translational results explaining the mechanisms of action of SST4 agonists as novel analgesic and antidepressant candidates.