Relapse-Associated Transient Synaptic Potentiation Requires Integrin-Mediated Activation of Focal Adhesion Kinase and Cofilin in D1-Expressing Neurons.

Relapse to drug use can be initiated by drug-associated cues. The intensity of cue-induced drug seeking in rodent models correlates with the induction of transient synaptic potentiation (t-SP) at glutamatergic synapses in the nucleus accumbens core (NAcore). Matrix metalloproteinases (MMPs) are inducible endopeptidases that degrade extracellular matrix (ECM) proteins, and reveal tripeptide Arginine-Glycine-Aspartate (RGD) domains that bind and signal through integrins. Integrins are heterodimeric receptors composed of αß subunits, and a primary signaling kinase is focal adhesion kinase (FAK). We previously showed that MMP activation is necessary for and potentiates cued reinstatement of cocaine seeking, and MMP-induced catalysis stimulates ß3-integrins to induce t-SP. Here, we determined whether ß3-integrin signaling through FAK and cofilin (actin depolymerization factor) is necessary to promote synaptic growth during t-SP. Using a small molecule inhibitor to prevent FAK activation, we blocked cued-induced cocaine reinstatement and increased spine head diameter (dh). Immunohistochemistry on NAcore labeled spines with ChR2-EYFP virus, showed increased immunoreactivity of phosphorylation of FAK (p-FAK) and p-cofilin in dendrites of reinstated animals compared with extinguished and yoked saline, and the p-FAK and cofilin depended on ß3-integrin signaling. Next, male and female transgenic rats were used to selectively label D1 or D2 neurons with ChR2-mCherry. We found that p-FAK was increased during drug seeking in both D1 and D2-medium spiny neurons (MSNs), but increased p-cofilin was observed only in D1-MSNs. These data indicate that ß3-integrin, FAK and cofilin constitute a signaling pathway downstream of MMP activation that is involved in promoting the transient synaptic enlargement in D1-MSNs induced during reinstated cocaine by drug-paired cues.SIGNIFICANCE STATEMENT Drug-associated cues precipitate relapse, which is correlated with transient synaptic enlargement in the accumbens core. We showed that cocaine cue-induced synaptic enlargement depends on matrix metalloprotease signaling in the extracellular matrix (ECM) through ß3-integrin to activate focal adhesion kinase (FAK) and phosphorylate the actin binding protein cofilin. The nucleus accumbens core (NAcore) contains two predominate neuronal subtypes selectively expressing either D1-dopamine or D2-dopamine receptors. We used transgenic rats to study each cell type and found that cue-induced signaling through cofilin phosphorylation occurred only in D1-expressing neurons. Thus, cocaine-paired cues initiate cocaine reinstatement and synaptic enlargement through a signaling cascade selectively in D1-expressing neurons requiring ECM stimulation of ß3-integrin-mediated phosphorylation of FAK (p-FAK) and cofilin.

Enhanced external counterpulsation for management of symptoms associated with long COVID.

Study objective: Enhanced external counterpulsation (EECP) as a possible therapy for Long COVID. Design: Retrospective analysis of a contemporary, consecutive patient cohort. Setting: 7 outpatient treatment centers. Participants: Long COVID patients. Intervention: 15-35 EECP treatments. Main outcome measures: The change from baseline in 1) Patient Reported Outcome Measurement Information System (PROMIS) Fatigue; 2) Seattle Angina Questionnaire (SAQ); 3) Duke Activity Status Index (DASI); 4) 6-Minute Walk Test (6MWT); 5) Canadian Cardiovascular Society (CCS) Angina Grade; 6) Rose Dyspnea Scale (RDS); and 7) Patient Health Questionnaire (PHQ-9). Results: Compared to baseline, the PROMIS Fatigue, SAQ, DASI, and 6MWT improved by 4.63 ± 3.42 (p < 0.001), 21.44 ± 16.54 (p < 0.001), 18.08 ± 13.82 (p < 0.001), and 200.00 ± 180.14 (p = 0.002), respectively. CCS and RDS improved in 63% and 44% of patients, respectively. All patients unable to work prior to EECP were able to return post-therapy. Conclusions and relevance: EECP significantly improved validated fatigue and cardiovascular-related markers in patients with Long COVID.

Management of Long-COVID Postural Orthostatic Tachycardia Syndrome With Enhanced External Counterpulsation.

A growing number of patients diagnosed with COVID-19 disease have been reported to have postural orthostatic tachycardia syndrome (POTS) after the acute phase. A 57-year-old female was diagnosed with COVID-19 in December 2020. As a result of her acute illness, she was hospitalized for COVID pneumonia and respiratory failure, followed by stays at an acute care facility and home rehabilitation center. After the acute phase, the patient was diagnosed with long-COVID-19-associated POTS with symptoms such as fatigue, "brain fog," and dyspnea. The patient was referred to an enhanced external counterpulsation (EECP) treatment center and underwent 15, one-hour sessions over three weeks. Upon completion of therapy, the patient reported improvements with "brain fog" and the ability to perform activities of daily living. Her Patient-Reported Outcome Measurement Information System (PROMIS) Fatigue score was reduced by three points, six-minute walk distance increased by 85 feet, and Duke Activity Status Index (DASI) improved by over 15 points. EECP therapy was chosen due to the overlap in underlying pathology driving POTS and the mechanisms of action of EECP. This report is the first case of using EECP for the successful management of COVID-19-associated POTS and warrants further trials.