Serotonin 1A agonist and cardiopulmonary improvements with whole-body exercise in acute, high-level spinal cord injury: a retrospective analysis

PURPOSE

High-level spinal cord injury (SCI) can result in spinal and supraspinal respiratory control deficits leading to insufficient ventilatory responses to exercise and training-related adaptations. We hypothesized a serotonin agonist, known to improve respiratory function in animal models, would improve adaptations to whole-body functional electrical stimulation (FES) exercise training in patients with acute high-level SCI.

METHODS

We identified 10 patients (< 2 years of injury with SCI from C4 to T3) in our program who had performed 6 months of FES-row training while on Buspirone (29 ± 17 mg/day) between 2012 and 2018. We also identified well-matched individuals who trained for six months but not on Buspirone (n = 11). A peak incremental FES-rowing exercise test and resting pulmonary function test had been performed before and after training.

RESULTS

Those on Buspirone demonstrated greater increases in peak oxygen consumption (VO₂peak: + 0.24 ± 0.23 vs. + 0.10 ± 0.13 L/min, p = 0.08) and peak ventilation (VEpeak: + 6.5 ± 8.1 vs. - 0.7 ± 6.9 L/min, p < 0.05) compared to control. In addition, changes in VO₂peak and VEpeak were correlated across all patients (r = 0.63, p < 0.01), but most strongly in those on Buspirone (r = 0.85, p < 0.01). Furthermore, changes in respiratory function correlated with increased peak tidal volume in the Buspirone group (r > 0.66, p < 0.05).

CONCLUSION

These results suggest Buspirone improves cardiorespiratory adaptations to FES-exercise training in individuals with acute, high-level SCI. The strong association between increases in ventilatory and aerobic capacities suggests improved respiratory function is a mechanism; however, controlled studies are needed to determine if this preliminary finding is reproducible.

Preliminary safety and efficacy profile of prucalopride in the treatment of systemic sclerosis (SSc)-related intestinal involvement: results from the open label cross-over PROGASS study

Background

Prokinetics are used to treat enteric dismotility symptoms in systemic sclerosis (SSc) patients, but they often lack adequate efficacy. The most effective prokinetics belonging to the serotonin (5-HT₄) receptor agonists class were withdrawn due to cardiac toxicity in relation to modest 5-HT₄ receptor affinity. Prucalopride is a high-affinity 5-HT₄ receptor agonist with no major cardiac issues, for which the efficacy in SSc has not yet been assessed.

Methods

Forty patients with self-reported mild to moderately severe enteric symptoms were enrolled in a cross-over 2 × 2 study. Subjects were randomized 1:1 to prucalopride 2 mg/day or no treatment for one month and vice versa after a 2-week washout period. Before and after each sequence the patients compiled the University of California Los Angeles gastrointestinal tract (UCLA GIT) 2.0 questionnaire and the numbers of complete intestinal movements were recorded. Oro-cecal transit time (OCTT) was evaluated by lactulose breath test in a subgroup of patients. Data were evaluated by mixed linear models corrected for the number of laxatives used during the study periods.

Results

There were 29 subjects who completed the study; 7 subjects withdrew due to side-effects and 4 subjects were not compliant with the study procedures. As compared to dummy treatment, prucalopride was associated with more intestinal evacuations (p < 0.001), improvement of UCLA GIT constipation (-0.672 ± 0.112 vs 0.086 ± 0.115; p < 0.001), reflux (-0.409 ± 0.094 vs 0.01 ± 0.096; p < 0.005) and bloating (-0.418 ± 0.088 vs -0.084 ± 0.09; p = 0.01) scores. Treatment was ranked moderately to more than moderately effective by 22 patients (72.4%). OCTT was significantly reduced during prucalopruide consumption (prucalopride: -20.1 ± 20.1 vs no treatment: 45.8 ± 21.3 minutes; treatment effect = -65.9 minutes; p = 0.035).

Conclusions

The safety profile of prucalopride in SSc is similar to what is known from the literature. In patients with mild to severe gastrointestinal problems, prucalopride may be effective in treating dismotility symptoms, increasing the number of complete bowel movements and improving bowel transit, reducing reflux disease and bloating.

Trial registration

EU Clinical Trial Registry, EudraCT2012-005348-92. Registered on 19 February 2013.

Acute pergolide exposure stiffens engineered valve interstitial cell tissues and reduces contractility in vitro

Medications based on ergoline-derived dopamine and serotonin agonists are associated with off-target toxicities that include valvular heart disease (VHD). Reports of drug-induced VHD resulted in the withdrawal of appetite suppressants containing fenfluramine and phentermine from the US market in 1997 and pergolide, a Parkinson's disease medication, in 2007. Recent evidence suggests that serotonin receptor activity affected by these medications modulates cardiac valve interstitial cell activation and subsequent valvular remodeling, which can lead to cardiac valve fibrosis and dysfunction similar to that seen in carcinoid heart disease. Failure to identify these risks prior to market and continued use of similar drugs reaffirm the need to improve preclinical evaluation of drug-induced VHD. Here, we present two complimentary assays to measure stiffness and contractile stresses generated by engineered valvular tissues in vitro. As a case study, we measured the effects of acute (24 h) pergolide exposure to engineered porcine aortic valve interstitial cell (AVIC) tissues. Pergolide exposure led to increased tissue stiffness, but it decreased both basal and active contractile tone stresses generated by AVIC tissues. Pergolide exposure also disrupted AVIC tissue organization (i.e., tissue anisotropy), suggesting that the mechanical properties and contractile functionality of these tissues are governed by their ability to maintain their structure. We expect further use of these assays to identify off-target drug effects that alter the phenotypic balance of AVICs, disrupt their ability to maintain mechanical homeostasis, and lead to VHD.