Fifty years of beta-adrenergic blockade: a golden era in clinical medicine and molecular pharmacology

The Adrenergic Nerve Network in Cancer

The central and autonomic nervous systems interact and converge to build up an adrenergic nerve network capable of promoting cancer. While a local adrenergic sympathetic innervation in peripheral solid tumors influences cancer and stromal cell behavior, the brain can participate to the development of cancer through an intermixed dysregulation of the sympathoadrenal system, adrenergic neurons, and the hypothalamo-pituitary-adrenal axis. A deeper understanding of the adrenergic nerve circuitry within the brain and tumors and its interactions with the microenvironment should enable elucidation of original mechanisms of cancer and novel therapeutic strategies.

Association of beta blocker use and hearing ability in adults: a cross-sectional study

OBJECTIVES

To investigate the potential association between beta blocker use and hearing ability in adults and to discern whether this effect is dose-dependent.

DESIGN

Cross-sectional analyses. Multiple linear regression was performed with hearing ability as the dependent variable and beta blocker use as the independent variable. The independent variable was classified into three dose categories for secondary analysis. Adjustments were made for age, gender, educational level, and tobacco smoking status.

STUDY SAMPLE

1636 adults, 75 of whom reported being on beta blockers, from the internet-based Netherlands Longitudinal Study on Hearing (NL-SH).

RESULTS

No significant association was found between beta blocker use and hearing ability in noise. In the adjusted regressions, beta blocker use changed the speech reception threshold in noise (SRT) by -0.04 dB signal-to-noise ratio (SNR) (95%CI [-0.67 to 0.58], p = 0.890). Medium dose beta blocker use changed SRT by -0.42 dB SNR (95%CI [-1.38 to 0.71], p = 0.433), while a high dose changed it by -0.26 dB SNR (95%CI [-1.74 to 1.4], p = 0.767).

CONCLUSIONS

No evidence was found for beta blocker-induced changes in hearing ability. Future studies on this topic should favour case-control and cohort study designs, while focussing on a hypertensive population to minimise confounding by indication.

Beta-Blockers and Cancer: Where Are We?

Cancer is one of the leading causes of death worldwide. After diagnosis, cancer treatment may involve radiotherapy, chemotherapy, and surgery. Several of the approaches used to treat cancer also attack normal cells and, thus, there is the need for more effective treatments that decrease the toxicity to normal cells and increase the success rates of treatment. The use of beta-blockers in cancer has been studied for their antagonist action on the adrenergic system through inhibition of beta-adrenergic receptors. Besides regulating processes such as blood pressure, heart rate, and airway strength or reactivity, beta-blockers block mechanisms that trigger tumorigenesis, angiogenesis, and tumor metastasis. This study presents a literature review of the available studies addressing cancer treatments and beta-blockers. Overall, data suggest that propranolol may be used as a complement for the treatment of several types of cancer due to its ability to improve cancer outcomes by decreasing cancer cell proliferation rates. Nonetheless, additional in vitro studies should be performed to fully understand the protective role of BBs in cancer patients.

The Preventive Role of Angiotensin Converting Enzyme Inhibitors/Angiotensin-II Receptor Blockers and β-Adrenergic Blockers in Anthracycline- and Trastuzumab-Induced Cardiotoxicity

Anthracycline (doxorubicin) and trastuzumab treatments for cancer patients have been known to cause cardiotoxicity. The current recommendations for prevention of cardiac events from cancer chemotherapies are largely based on opinion. The American Society of Clinical Oncology recommends active screening and prevention of modifiable cardiovascular risk factors. The risk factors are defined as tobacco use, high blood pressure, high cholesterol, alcohol use, obesity, and physical inactivity. Beta-adrenergic blockers and angiotensin converting enzyme (ACE) inhibitors/angiotensin receptor blockers (ARBs) have been the mainstay of treatment for heart failure patients with reduced left ventricular ejection fraction for many years. This review analyzed the use of beta-adrenergic blockers and ACE inhibitors/ARBs as protection against cardiomyopathy caused by anthracyclines and trastuzumab. Although many more studies are warranted, it was concluded that the addition of a beta-blocker early in the treatment of cancer patients who are undergoing anthracycline or trastuzumab treatment can have beneficial effects in preserving left ventricular ejection fraction and preventing chemotherapy-induced cardiotoxicity. The effects are more apparent in the short term. More studies of the long-term effects are warranted, as are the additive effects of using a beta-blocker and ACE inhibitor/ARB together to prevent chemotherapy-induced cardiotoxicity.

Beta-blockers: Historical Perspective and Mechanisms of Action

Beta-blockers are widely used molecules that are able to antagonize β-adrenergic receptors (ARs), which belong to the G protein-coupled receptor family and receive their stimulus from endogenous catecholamines. Upon β-AR stimulation, numerous intracellular cascades are activated, ultimately leading to cardiac contraction or vascular dilation, depending on the relevant subtype and their location. Three subtypes have been described that are differentially expressed in the body (β₁-, β₂- and β₃-ARs), β₁ being the most abundant subtype in the heart. Since their discovery, β-ARs have become an important target to fight cardiovascular disease. In fact, since their discovery by James Black in the late 1950s, β-blockers have revolutionized the field of cardiovascular therapies. To date, 3 generations of drugs have been released: nonselective β-blockers, cardioselective β-blockers (selective β₁-antagonists), and a third generation of these drugs able to block β₁ together with extra vasodilation activity (also called vasodilating β-blockers) either by blocking α₁- or by activating β₃-AR. More than 50 years after propranolol was introduced to the market due to its ability to reduce heart rate and consequently myocardial oxygen demand in the event of an angina attack, β-blockers are still widely used in clinics.

Beta-Adrenergic Receptor Blockers in Hypertension: Alive and Well

Beta-adrenergic receptor blockers (β-blockers) are an appropriate treatment for patients having systemic hypertension (HTN) who have concomitant ischemic heart disease (IHD), heart failure, obstructive cardiomyopathy, aortic dissection or certain cardiac arrhythmias. β-Blockers can be used in combination with other antiHTN drugs to achieve maximal blood pressure control. Labetalol can be used in HTN emergencies and urgencies. β-Blockers may be useful in HTN patients having a hyperkinetic circulation (palpitations, tachycardia, HTN, and anxiety), migraine headache, and essential tremor. β-Blockers are highly heterogeneous with respect to various pharmacologic properties: degree of intrinsic sympathomimetic activity, membrane stabilizing activity, β₁ selectivity, α₁-adrenergic blocking effects, tissue solubility, routes of systemic elimination, potencies and duration of action, and specific properties may be important in the selection of a drug for clinical use. β-Blocker usage to reduce perioperative myocardial ischemia and cardiovascular (CV) complications may not benefit as many patients as was once hoped, and may actually cause harm in some individuals. Currently the best evidence supports perioperative β-blocker use in two patient groups: patients undergoing vascular surgery with known IHD or multiple risk factors for it, and for those patients already receiving β-blockers for known CV conditions.

β-blocking agents for surgery: influence on mortality and major outcomes. A meta-analysis

OBJECTIVE

To re-evaluate the effects of perioperative beta-blockade on mortality and major outcomes after surgery.

DESIGN

A meta-analysis of parallel randomized, controlled trials published in English.

SETTING

A university-based electronic search.

PARTICIPANTS

Patients undergoing surgery.

INTERVENTIONS

Two interventions were evaluated: (1) Stopping or continuing a β-blocker in patients on long-term β-blocker therapy; and (2) Adding a β-blocker for the perioperative period.

MEASUREMENTS AND MAIN RESULTS

Stopping a β-blocker before the surgery did not change the risk of myocardial infarction (3 studies including 97 patients): risk ratio (RR), 1.08 (95% confidence interval 0.30, 3.95); I(2), 0%. Adding a β-blocker reduced the risk of death at 1 year: RR, 0.56 (0.31, 0.99); I(2), 0%; p = 0.046; number needed to treat 28 (19, 369) (4 studies with 781 patients). Adding a β-blocker reduced the 0-to-30 day risk of myocardial infarction: RR, 0.65 (0.47, 0.88); I(2), 12.9%; p = 0.006 (15 studies with 12,224 patients), but increased the risk of a stroke: RR, 2.18 (1.40, 3.38); I(2), 0%; p = 0.001 (8 studies with 11,737 patients); number needed to harm 177 (512, 88).

CONCLUSIONS

β-blockers reduced the 1-year risk of death, and this effect seemed greater than the risk of inducing a stroke.

Beta-adrenergic receptors, from their discovery and characterization through their manipulation to beneficial clinical application

β-Adrenergic receptors (β-AR) are central to the overall regulation of cardiac function. From the first proposed receptor/transmitter concept to the latest clinical β-blocker trials β-AR have been shown to play an important role in cardiac disease and heart failure in particular. This study provides a historical perspective, reviews the latest discoveries and beliefs, and discusses the current clinical practices of β-AR and their modulation with their associated guanine-nucleotide regulatory protein/adenylylcyclasesignal transduction pathways.

Cardiac aging: from molecular mechanisms to significance in human health and disease

Cardiovascular diseases (CVDs) are the major causes of death in the western world. The incidence of cardiovascular disease as well as the rate of cardiovascular mortality and morbidity increase exponentially in the elderly population, suggesting that age per se is a major risk factor of CVDs. The physiologic changes of human cardiac aging mainly include left ventricular hypertrophy, diastolic dysfunction, valvular degeneration, increased cardiac fibrosis, increased prevalence of atrial fibrillation, and decreased maximal exercise capacity. Many of these changes are closely recapitulated in animal models commonly used in an aging study, including rodents, flies, and monkeys. The application of genetically modified aged mice has provided direct evidence of several critical molecular mechanisms involved in cardiac aging, such as mitochondrial oxidative stress, insulin/insulin-like growth factor/PI3K pathway, adrenergic and renin angiotensin II signaling, and nutrient signaling pathways. This article also reviews the central role of mitochondrial oxidative stress in CVDs and the plausible mechanisms underlying the progression toward heart failure in the susceptible aging hearts. Finally, the understanding of the molecular mechanisms of cardiac aging may support the potential clinical application of several "anti-aging" strategies that treat CVDs and improve healthy cardiac aging.

About strawberry, crab claws, and the Sir James Black's invention. Hypothesis: can we battle keloids with propranolol?

The cutaneous hemangiomas of infancy or infantile hemangiomas are the most common benign tumor of childhood. They were formerly known as strawberry hemangiomas in reason of its typical appearance although uncommon morphologic variations can be found. Usually hemangiomas are harmless growths that are the result of proliferation of endothelial cells during early childhood. Involution of the lesion occurs at 12-18 months and can last up to 7 years. Occasionally, infantile hemangiomas suffer dramatic overgrowth causing esthetical damages, as well compromises to vital structures that requires prompt intervention. Propranolol, a beta-adrenergic receptor antagonist that was invented by Sir James Black in 1960s, appears to be an effective treatment for infantile hemangiomas and should now be used as a first-line treatment in hemangiomas when intervention is required. Keloids (that resembles crab claws) and hypertrophic scars are fibrous tissue outgrowths that result from a derailment in the normal wound-healing process. Systemic or intralesional propranolol may play a role in the amelioration of keloids and hypertrophic scars due to their potential to induce vasoconstriction of over proliferating tissues, triggering apoptosis of endothelial cells and also to their effect as modulator of inflammatory process during wound healing. In adding the propranolol to the melting pot of abnormal (or supra-normal) wound healing, we hypothesized that we can battle keloids with propranolol.