Response to catecholamine stimulation of polymorphisms of the beta-1 and beta-2 adrenergic receptors

Serotonin Syndrome Following Terbutaline Administration in a Heart Transplant Patient on Multiple Inotropic Agents: A Case Report

The significance of serotonin syndrome due to drug-drug interactions has emerged as a prominent consideration when the effects of polypharmacy are reviewed. The emergence of the selective serotonin reuptake inhibitors has most likely fueled the increased reporting of serotonin syndrome in the literature, leading to increased awareness of this phenomenon. However, their presence is not necessarily inclusive to a case and the utilization of agents precipitating an occurrence may be unavoidable. We report a case of serotonin syndrome occurring in a heart transplant patient without the presence of any of the usual suspect agents involved. In the postoperative course, the patient developed cardiogenic shock with vasoplegia requiring continuation of inotropic therapy along with vasopressor support of epinephrine. Oral terbutaline was begun for hemodynamic improvement. The patient's tenuous mental status rapidly deteriorated after addition of the terbutaline, with symptoms consistent with serotonin syndrome. Administration of cyproheptadine, a known reversal agent for serotonin toxicity, rapidly alleviated the adverse symptoms.

The hemodynamic response to constant dobutamine infusion: the effect of ADRB1 389 polymorphism and sex

OBJECTIVES

Prolonged activation of the β-1 adrenergic receptor (ADRB1) is associated with receptor desensitization. This process has been suggested to have important pathophysiological and clinical implications in conditions such as congestive heart failure. The contribution of genetic factors to this process is a subject of ongoing research. We have previously shown that the ADRB1 389 polymorphism affects the response to incremental dose infusion of the ADRB agonist dobutamine. The aim of the current study was to determine whether the ADRB1 389 polymorphism affects the hemodynamic response to constant dose infusion of dobutamine in healthy patients.

PATIENTS AND METHODS

Healthy patients were recruited according to their ADRB1 49 and 389 genotypes [15 Arg389Arg, 10 Gly389Arg, and 10 Gly389Gly patients (all Ser49Ser), 21 men and 14 women]. Following a standardized protocol of dose increase, 6 mcg/kg/min dobutamine was infused over 2 h. Heart rate (HR), blood pressure (BP), and active plasma renin (PR) were measured. Standardized exercise (1 min) was performed at three time points during infusion.

RESULTS

In all patients, resting systolic BP was significantly decreased during infusion [144.4±11.5 vs. 140.3±12.2 mmHg (mean±SD), P=0.007]. There was no change in HR, and PR following 120 min of dobutamine infusion. ADRB1 389 genotypes were not associated with HR, systolic BP, and PR changes during dobutamine infusion (all P>0.05, repeated measures analysis of variance). Sex was associated with response to dobutamine. Among women, but not in men, resting HR significantly increased, and diastolic blood pressure (DBP) significantly decreased during dobutamine infusion [HR: 76.0±7.3 to 86.3±17.5 beats per minute (P=0.023), and DBP 78.5±8.49 mmHg to 72.36±6.16 (P=0.041) (repeated measures analysis of variance)].

CONCLUSION

In healthy patients, the ADRB1 389 genotype was not associated with hemodynamic changes during constant dobutamine infusion. In women, but not in men, HR significantly increased and DBP decreased during 2 h of infusion.

Discovery of 7-hydroxyaporphines as conformationally restricted ligands for beta-1 and beta-2 adrenergic receptors

A series of (-)-nornuciferidine derivatives was synthesized and the non-natural enantiomer of the aporphine alkaloid was discovered to be a potent β1- and β2-adrenergic receptor ligand that antagonized isoproterenol and procaterol induced cyclic AMP increases from adenylyl cyclase, respectively. Progressive deconstruction of the tetracyclic scaffold to less complex cyclic and acyclic analogues revealed that the conformationally restricted (6a-R,7-R)-7-hydroxyaporphine 2 (AK-2-202) was necessary for efficient receptor binding and antagonism.

Predicted Biological Activity of Purchasable Chemical Space

Whereas 400 million distinct compounds are now purchasable within the span of a few weeks, the biological activities of most are unknown. To facilitate access to new chemistry for biology, we have combined the Similarity Ensemble Approach (SEA) with the maximum Tanimoto similarity to the nearest bioactive to predict activity for every commercially available molecule in ZINC. This method, which we label SEA+TC, outperforms both SEA and a naïve-Bayesian classifier via predictive performance on a 5-fold cross-validation of ChEMBL’s bioactivity data set (version 21). Using this method, predictions for over 40% of compounds (>160 million) have either high significance (pSEA ≥ 40), high similarity (ECFP4MaxTc ≥ 0.4), or both, for one or more of 1382 targets well described by ligands in the literature. Using a further 1347 less-well-described targets, we predict activities for an additional 11 million compounds. To gauge whether these predictions are sensible, we investigate 75 predictions for 50 drugs lacking a binding affinity annotation in ChEMBL. The 535 million predictions for over 171 million compounds at 2629 targets are linked to purchasing information and evidence to support each prediction and are freely available via https://zinc15.docking.org and https://files.docking.org.

Adrenergic Receptor Polymorphism and Maximal Exercise Capacity after Orthotopic Heart Transplantation

Background

Maximal exercise capacity after heart transplantion (HTx) is reduced to the 50–70% level of healthy controls when assessed by cardiopulmonary exercise testing (CPET) despite of normal left ventricular function of the donor heart. This study investigates the role of donor heart β₁ and β₂- adrenergic receptor (AR) polymorphisms for maximal exercise capacity after orthotopic HTx.

Methods

CPET measured peak VO₂ as outcome parameter for maximal exercise in HTx recipients ≥9 months and ≤4 years post-transplant (n = 41; mean peak VO₂: 57±15% of predicted value). Donor hearts were genotyped for polymorphisms of the β₁-AR (Ser49Gly, Arg389Gly) and the β₂-AR (Arg16Gly, Gln27Glu). Circumferential shortening of the left ventricle was measured using magnetic resonance based CSPAMM tagging.

Results

Peak VO₂ was higher in donor hearts expressing the β₁-Ser49Ser alleles when compared with β₁-Gly49 carriers (60±15% vs. 47±10% of the predicted value; p = 0.015), and by trend in cardiac allografts with the β₁-AR Gly389Gly vs. β₁-Arg389 (61±15% vs. 54±14%, p = 0.093). Peak VO2 was highest for the haplotype Ser49Ser-Gly389, and decreased progressively for Ser49Ser-Arg389Arg > 49Gly-389Gly > 49Gly-Arg389Arg (adjusted R² = 0.56, p = 0.003). Peak VO₂ was not different for the tested β₂-AR polymorphisms. Independent predictors of peak VO₂ (adjusted R² = 0.55) were β₁-AR Ser49Gly SNP (p = 0.005), heart rate increase (p = 0.016), and peak systolic blood pressure (p = 0.031). Left ventricular (LV) motion kinetics as measured by cardiac MRI CSPAMM tagging at rest was not different between carriers and non-carriers of the β₁-AR Gly49allele.

Conclusion

Similar LV cardiac motion kinetics at rest in donor hearts carrying either β₁-AR Gly49 or β₁-Ser49Ser variant suggests exercise-induced desensitization and down-regulation of the β₁-AR Gly49 variant as relevant pathomechanism for reduced peak VO₂ in β₁-AR Gly49 carriers.

A review of potential pharmacogenetic effects on catecholamine responses

Considerably, variability in the clinical response to inotropic agents is observed and could be explained partially by the genetic variants, such as single-nucleotide polymorphism (SNP) in genes encoding for enzymes implicated in catecholamines synthesis, metabolism, storage and release or in the signaling pathway. This review highlights the potential effect of pharmacogenetics studies in hemodynamic response and identified 11 SNPs that could be relevant to explain the high variability drug response for a same dose. Cardiovascular instability, such as hypotension, is one of the premature birth complications. The pharmacogenetics studies evaluating these SNP may be useful to better understand the clinical outcome, particularly in this population.

Biopsychosocial influence on exercise-induced injury: genetic and psychological combinations are predictive of shoulder pain phenotypes

Chronic pain is influenced by biological, psychological, social, and cultural factors. The current study investigated potential roles for combinations of genetic and psychological factors in the development and/or maintenance of chronic musculoskeletal pain. An exercise-induced shoulder injury model was used, and a priori selected genetic (ADRB2, COMT, OPRM1, AVPR1 A, GCH1, and KCNS1) and psychological (anxiety, depressive symptoms, pain catastrophizing, fear of pain, and kinesiophobia) factors were included as predictors. Pain phenotypes were shoulder pain intensity (5-day average and peak reported on numerical rating scale), upper extremity disability (5-day average and peak reported on the QuickDASH), and shoulder pain duration (in days). After controlling for age, sex, and race, the genetic and psychological predictors were entered as main effects and interaction terms in separate regression models for the different pain phenotypes. Results from the recruited cohort (N = 190) indicated strong statistical evidence for interactions between the COMT diplotype and 1) pain catastrophizing for 5-day average upper extremity disability and 2) depressive symptoms for pain duration. There was moderate statistical evidence for interactions for other shoulder pain phenotypes between additional genes (ADRB2, AVPR1 A, and KCNS1) and depressive symptoms, pain catastrophizing, or kinesiophobia. These findings confirm the importance of the combined predictive ability of COMT with psychological distress and reveal other novel combinations of genetic and psychological factors that may merit additional investigation in other pain cohorts.

PERSPECTIVE

Interactions between genetic and psychological factors were investigated as predictors of different exercise-induced shoulder pain phenotypes. The strongest statistical evidence was for interactions between the COMT diplotype and pain catastrophizing (for upper extremity disability) or depressive symptoms (for pain duration). Other novel genetic and psychological combinations were identified that may merit further investigation.

Impact of polymorphic variants on the molecular pharmacology of the two-agonist conformations of the human β1-adrenoceptor

β-blockers are widely used to improve symptoms and prolong life in heart disease primarily by inhibiting the actions of endogenous catecholamines at the β1-adrenoceptor. There are two common naturally occurring polymorphisms within the human β1-adrenoceptor sequence: Ser or Gly at position 49 in the N-terminus and Gly or Arg at position 389 in the C-terminus and some clinical studies have suggested that expression of certain variants may be associated with disease and affect response to treatment with β-blockers. The β1-adrenoceptor also exists in two agonist conformations - a high affinity catecholamine conformation and a low affinity secondary agonist conformation. Receptor-effector coupling and intracellular signalling from the different conformations may be affected by the polymorphic variants. Here, we examine in detail the molecular pharmacology of the β1-adrenoceptor polymorphic variants with respect to ligand affinity, efficacy, activation of the different agonist conformations and signal transduction and determine whether the polymorphic variants do indeed affect this secondary conformation. Stable cell lines expressing the wildtype and polymorphic variants were constructed and receptor pharmacology examined using whole cell binding and intracellular secondary messenger techniques. There was no difference in affinity for agonists and antagonists at the human wildtype β1-adrenoceptor (Ser49/Gly389) and the polymorphic variants Gly49/Gly389 and Ser49/Arg389. Furthermore, the polymorphic variant receptors both have two active agonist conformations with pharmacological properties similar to the wildtype receptor. Although the polymorphism at position 389 is thought to occur in an intracellular domain important for Gs-coupling, the two agonist conformations of the polymorphic variants stimulate intracellular signalling pathways, including Gs-cAMP intracellular signalling, in a manner very similar to that of the wildtype receptor.