Betel Quid Addiction: A Review of Its Addiction Mechanisms and Pharmacological Management as an Emerging Modality for Habit Cessation

Functions and pharmacology of α2β2 nicotinic acetylcholine receptors; in and out of the shadow of α4β2 nicotinic acetylcholine receptors

Although α2 was the first neuronal nicotinic acetylcholine receptor (nAChR) receptor subunit to be cloned, due to its low level of expression in rodent brain, its study has largely been neglected. This study provides a comparison of the α2 and α4 structures and their functional similarities, especially in regard to the existence of low and high sensitivity forms based on subunit stoichiometry. We show that the pharmacological profiles of the low and high sensitivity forms of α2β2 and α4β2 receptors are very similar in their responses to nicotine, with high sensitivity receptors showing protracted responses. Sazetidine A, an agonist that is selective for the high sensitivity α4 receptors also selectively activates high sensitivity α2 receptors. Likewise, α2 receptors have similar responses as α4 receptors to the positive allosteric modulators (PAMs) desformylflustrabromine (dFBr) and NS9283. We show that the partial agonists for α4β2 receptors, cytisine and varenicline are also partial agonists for α2β2 receptors. Studies have shown that levels of α2 expression may be much higher in the brains of primates than those of rodents, suggesting a potential importance for human therapeutics. High-affinity nAChR have been studied in humans with PET ligands such as flubatine. We show that flubatine has similar activity with α2β2 and α4β2 receptors so that α2 receptors will also be detected in PET studies that have previously presumed to selectively detect α4β2 receptors. Therefore, α2 receptors need more consideration in the development of therapeutics to manage nicotine addiction and declining cholinergic function in age and disease.

Biological Effects and Biomedical Applications of Areca Nut and Its Extract

The dried, mature fruit of the palm tree species Areca catechu L. is known as the areca nut (AN) or betel nut. It is widely cultivated in the tropical regions. In many nations, AN is utilized for traditional herbal treatments or social activities. AN has historically been used to address various health issues, such as diarrhea, arthritis, dyspepsia, malaria, and so on. In this review, we have conducted a comprehensive summary of the biological effects and biomedical applications of AN and its extracts. Initially, we provided an overview of the constituents in AN extract. Subsequently, we summarized the biological effects of AN and its extracts on the digestive system, nervous system, and circulatory system. And we elucidated the contributions of AN and its extracts in antidepressant, anti-inflammatory, antioxidant, and antibacterial applications. Finally, we have discussed the challenges and future perspectives regarding the utilization of AN and its extracts as emerging pharmaceuticals or valuable adjuncts within the pharmaceutical field.

An overview of the burden of oral cancer in Sri Lanka and its inequalities in the face of contemporary economic and social malaise

OBJECTIVES

Over the past several decades, oral cancer has been the most common malignancy among Sri Lankan males and the top 10 cancer among females, disproportionately affecting low socio-economic groups. Sri Lanka is a lower-middle-income developing country (LMIC), currently striking through an economic crisis, and social and political unrest. Occurring at an accessible body site and predominantly attributed to potentially modifiable health-related behaviours, oral cancer should be preventable and controllable. Unfortunately, broader contextual factors that are socio-cultural, environmental, economic, and political and mediated through social determinants of people's lives consistently hinder progress. Many LMICs with a high burden of oral cancer are now gripped by economic crises, consequent social and political unrest, all compounded by reduced public health investments. The aim of this review is to provide a critical commentary on key aspects of oral cancer epidemiology including inequalities, using Sri Lanka as a case study.

METHODS

The review synthesizes evidence from multiple data sources, such as published studies, web-based national cancer incidence data, national surveys on smokeless tobacco (ST) and areca nut use, smoking and alcohol consumption, poverty headcount ratios, economic growth, and Gross Domestic Product (GDP) health expenditure. National trends in the oral cancer, ST use, smoking and alcohol consumption in Sri Lanka are identified alongside inequalities.

RESULTS

Using these evidence sources, we discuss 'where are we now?', together with the availability, accessibility and affordability of oral cancer treatment services, oral cancer prevention and control programmes, tobacco and alcohol control policies, and finally, outline macroeconomic perspectives of Sri Lanka.

CONCLUSIONS

Finally, we speculate, 'where to next?' Our overarching goal of this review is to initiate a critical discourse on bridging the gaps and crossing the divides to tackle oral cancer inequalities in LMIC such as Sri Lanka.

The Controversial Roles of Areca Nut: Medicine or Toxin?

Areca nut (AN) is used for traditional herbal medicine and social activities in several countries. It was used as early as about A.D. 25-220 as a remedy. Traditionally, AN was applied for several medicinal functions. However, it was also reported to have toxicological effects. In this review article, we updated recent trends of research in addition to acquire new knowledge about AN. First, the history of AN usage from ancient years was described. Then, the chemical components of AN and their biological functions was compared; arecoline is an especially important compound in AN. AN extract has different effects caused by different components. Thus, the dual effects of AN with pharmacological and toxicological effects were summarized. Finally, we described perspectives, trends and challenges of AN. It will provide the insight of removing or modifying the toxic compounds of AN extractions for enhancing their pharmacological activity to treat several diseases in future applications.

Betel quid: New insights into an ancient addiction

The use of areca nuts (areca) in the form of betel quids constitutes the fourth most common addiction in the world, associated with high risk for oral disease and cancer. Areca is a complex natural product, making it difficult to identify specific components associated with the addictive and carcinogenic properties. It is commonly believed that the muscarinic agonist arecoline is at the core of the addiction. However, muscarinic receptor activation is not generally believed to support drug-taking behaviour. Subjective accounts of areca use include descriptions of both sedative and stimulatory effects, consistent with the presence of multiple psychoactive agents. We have previously reported partial agonism of α4-containing nicotinic acetylcholine receptors by arecoline and subsequent inhibition of those receptors by whole areca broth. In the present study, we report the inhibition of nicotinic acetylcholine receptors and other types of neurotransmitter receptors with compounds of high molecular weight in areca and the ability of low molecular weight areca extract to activate GABA and glutamate receptors. We confirm the presence of a high concentration of GABA and glutamate in areca. Additionally, data also indicate the presence of a dopamine and serotonin transporter blocking activity in areca that could account for the reported stimulant and antidepressant activity. Our data suggest that toxic elements of high molecular weight may contribute to the oral health liability of betel quid use, while two distinct low molecular weight components may provide elements of reward, and the nicotinic activity of arecoline contributes to the physical dependence of addiction.