Central Sympatholytic Drugs

Comparison of the cardiovascular effects of immobilization with three different drug combinations in free-ranging African lions

Thirty-six free-ranging lions (12 per group) were immobilized with tiletamine-zolazepam (Zoletil 0.6 mg/kg i.m.) plus medetomidine (0.036 mg/kg i.m.) (TZM), ketamine (3.0 mg/kg i.m.) plus medetomidine (0.036 mg/kg i.m.) (KM) or ketamine (1.2 mg/kg i.m.) plus butorphanol (0.24 mg/kg i.m.) plus medetomidine (0.036 mg/kg i.m.) (KBM). During immobilization cardiovascular variables were monitored at 5-minute intervals for a period of 30 minutes. Lions immobilized with all three drug combinations were severely hypertensive. Systolic arterial pressure was higher at initial sampling in lions immobilized with KM (237.3 ± 24.8 mmHg) than in those immobilized with TZM (221.0 ± 18.1 mmHg) or KBM (226.0 ± 20.6 mmHg) and decreased to 205.8 ± 19.4, 197.7 ± 23.7 and 196.3 ± 17.7 mmHg, respectively. Heart rates were within normal ranges for healthy, awake lions and decreased throughout the immobilization regardless of drug combination used. Lions immobilized with TZM had a higher occurrence (66%) of skipped heart beats than those immobilized with KBM (25%). The three drug combinations all caused negative cardiovascular effects, which were less when KBM was used, but adverse enough to warrant further investigations to determine if these effects can be reversed or prevented when these three combinations are used to immobilize free-living lions.

Blood pressure reduction induced by chronic intracerebroventricular or peroral clonidine administration in rats with salt-dependent or angiotensin II-dependent hypertension

The agonists of α2-adrenergic receptors such as clonidine, rilmenidine or monoxidine are known to lower blood pressure (BP) through a reduction of brain sympathetic outflow but their chronic antihypertensive effects in rats with low-renin or high-renin forms of experimental hypertension were not studied yet. Moreover, there is no comparison of mechanisms underlying BP reduction elicited by chronic peroral (po) or intracerebroventricular (icv) clonidine treatment. Male salt-sensitive Dahl rats fed 4% NaCl diet and Ren-2 transgenic rats were treated with clonidine administered either in the drinking fluid (0.5 mg/kg/day po) or as the infusion into lateral brain ventricle (0.1 mg/kg/day icv) for 4 weeks. Basal BP and the contributions of renin-angiotensin system (captopril 10 mg/kg iv) or sympathetic nervous system (pentolinium 5 mg/kg iv) to BP maintenance were determined in conscious cannulated rats at the end of the study. Both peroral and intracerebroventricular clonidine treatment lowered BP to the same extent in either rat model. However, in both models chronic clonidine treatment reduced sympathetic BP component only in rats treated intracerebroventricularly but not in perorally treated animals. In contrast, peroral clonidine treatment reduced angiotensin II-dependent vasoconstriction in Ren-2 transgenic rats, whereas it lowered residual blood pressure in Dahl rats. In conclusions, our results indicate different mechanisms of antihypertensive action of clonidine when administered centrally or systemically.

Blood pressure reduction induced by chronic intracerebroventricular or peroral clonidine administration in rats with salt-dependent or angiotensin II-dependent hypertension

The agonists of alpha(2)-adrenergic receptors such as clonidine, rilmenidine or monoxidine are known to lower blood pressure (BP) through a reduction of brain sympathetic outflow but their chronic antihypertensive effects in rats with low-renin or high-renin forms of experimental hypertension were not studied yet. Moreover, there is no comparison of mechanisms underlying BP reduction elicited by chronic peroral (po) or intracerebroventricular (icv) clonidine treatment. Male salt-sensitive Dahl rats fed 4% NaCl diet and Ren-2 transgenic rats were treated with clonidine administered either in the drinking fluid (0.5 mg/kg/day po) or as the infusion into lateral brain ventricle (0.1 mg/kg/day icv) for 4 weeks. Basal BP and the contributions of renin-angiotensin system (captopril 10 mg/kg iv) or sympathetic nervous system (pentolinium 5 mg/kg iv) to BP maintenance were determined in conscious cannulated rats at the end of the study. Both peroral and intracerebroventricular clonidine treatment lowered BP to the same extent in either rat model. However, in both models chronic clonidine treatment reduced sympathetic BP component only in rats treated intracerebroventricularly but not in perorally treated animals. In contrast, peroral clonidine treatment reduced angiotensin II-dependent vasoconstriction in Ren-2 transgenic rats, whereas it lowered residual blood pressure in Dahl rats. In conclusions, our results indicate different mechanisms of antihypertensive action of clonidine when administered centrally or systemically.

Drug-Induced Rhinitis: Narrative Review

OBJECTIVES

Rhinitis, one of the most common inflammatory conditions of the nasal mucosa, is known to affect a large proportion of people worldwide. It is generally classified into allergic and non-allergic types and both are associated with several unpleasant symptoms. Several medications prescribed for different medical conditions can cause unpleasant rhinitis as an adverse effect, which is known as drug-induced non-allergic rhinitis. The aims of this article were to review the literature to identify drugs that could induce rhinitis, prevalence of drug-induced rhinitis, and the associated pathogenic mechanisms if known.

METHODS

Literature search screening for eligible papers published up to December 31st, 2021, in Medline (via PubMed) and Embase was conducted. The search included the following combination of keywords and terms: rhinitis, sneezing, congestion, allergic, non-allergic, rhinorrhea, vasomotor, medication, drug-induced.

RESULTS

The review findings suggest that 12 subtypes of drugs potentially could induce rhinitis. Based on their mechanisms of action, the pathogenic causes for the induction of rhinitis have been recognized for some drugs, while others remain unknown.

CONCLUSION

Awareness of the list of drugs that reportedly induce non-allergic nasal symptoms, along with taking the patient's medication history, is important in the diagnosis of rhinitis.

Guanabenz-an old drug with a potential to decrease obesity

The aim of this study was to determine, in the diet-induced obesity model in rats, the potential of Guanabenz to reduce body weight and ameliorate some metabolic disturbances. Obesity was induced in rats by a high-fat diet. After 10 weeks, rats were treated intraperitoneally with Guanabenz at the two doses: 2 or 5 mg/kg b.w./day, once daily for 25 days. The spontaneous activity of rats was measured for 24 h on the 1st and 24th day of the Guanabenz treatment with a special radio-frequency identification system. Gastric emptying was measured in intragastric phenol red-treated mice by measuring the color of the stomach homogenate 30 min after phenol red administration. Intraperitoneal administration of Guanabenz for 25 days to obese rats resulted in a significant decrease in body weight compared to the baseline values (about 11% at a dose of 5 mg/kg). Both body weight and the amount of adipose tissue in the groups receiving Guanabenz decreased to the levels observed in the control rats fed only standard feed. The anorectic effect occurred in parallel with a reduction in plasma triglyceride levels. We also confirmed the beneficial effect of Guanabenz on plasma glucose level. The present study demonstrates that the administration of Guanabenz strongly inhibits gastric emptying (about 80% at a dose of 5 mg/kg). Guanabenz can successfully and simultaneously attenuate all the disorders and risk factors of metabolic syndrome: hypertension, hyperglycemia, obesity, and dyslipidemia. However, the exact cellular mechanisms of its action require further research.

Sustainability of blood pressure reduction in black barbershops

PURPOSE OF REVIEW

The prevalence of hypertension (HTN) among non-Hispanic blacks increased from 41 to 55% with the release of the new 2017 ACC/AHA guidelines - the highest among any racial group. Non-Hispanic black men have less physician interaction and lower blood pressure (BP) treatment and control rates when compared with their female counterparts, necessitating community outreach. Here, we review the Los Angeles Barbershop Blood Pressure Study (LABBPS) which demonstrated a community-based approach involving pharmacists, physicians, and barbers could improve BP control rates among black men.

RECENT FINDINGS

LABBPS was a cluster-randomized trial that evaluated both the efficacy and sustainability of a pharmacist-led HTN management program in which barbers promoted follow-up with pharmacists who prescribed antihypertensive therapy under collaborative practice agreements with intervention participant's primary care providers. After 6 months researchers observed a 21 mmHg greater fall in SBP among intervention group participants when compared with the control group participants who received 'usual care.' The 6-month extension phase of the study showed that the impressive BP reduction achieved was sustained with less pharmacist contact.

SUMMARY

Multidisciplinary, community-based approaches to HTN management can be effective and are necessary to tackle the current disparity seen in BP control rates. The model developed in LABBPS represents one such approach.

Melatonin attenuates renal sympathetic overactivity and reactive oxygen species in the brain in neurogenic hypertension

Sympathetic overactivation contributes to the pathogenesis of both experimental and human hypertension. We have previously reported that oxidative stress in sympathetic premotor neurons leads to arterial baroreflex dysfunction and increased sympathetic drive to the kidneys in an experimental model of neurogenic hypertension. In this study, we hypothesized that melatonin, a potent antioxidant, may be protective in the brainstem regions involved in the tonic and reflex control of blood pressure (BP) in renovascular hypertensive rats. Neurogenic hypertension was induced by placing a silver clip (gap of 0.2 mm) around the left renal artery, and after 5 weeks of renal clip placement, the rats were treated orally with melatonin (30 mg/kg/day) by gavage for 15 days. At the end of melatonin treatment, we evaluated baseline mean arterial pressure (MAP), renal sympathetic nerve activity (rSNA), and the baroreflex control of heart rate (HR) and rSNA. Reactive oxygen species (ROS) were detected within the brainstem regions by dihydroethidium staining. Melatonin treatment effectively reduced baseline MAP and sympathoexcitation to the ischemic kidney in renovascular hypertensive rats. The baroreflex control of HR and rSNA were improved after melatonin treatment in the hypertensive group. Moreover, there was a preferential decrease in ROS within the rostral ventrolateral medulla (RVLM) and the nucleus of the solitary tract (NTS). Therefore, our study indicates that melatonin is effective in reducing renal sympathetic overactivity associated with decreased ROS in brainstem regions that regulate BP in an experimental model of neurogenic hypertension.

A Guide to Medications Inducing Salivary Gland Dysfunction, Xerostomia, and Subjective Sialorrhea: A Systematic Review Sponsored by the World Workshop on Oral Medicine VI

BACKGROUND

Medication-induced salivary gland dysfunction (MISGD), xerostomia (sensation of oral dryness), and subjective sialorrhea cause significant morbidity and impair quality of life. However, no evidence-based lists of the medications that cause these disorders exist.

OBJECTIVE

Our objective was to compile a list of medications affecting salivary gland function and inducing xerostomia or subjective sialorrhea.

DATA SOURCES

Electronic databases were searched for relevant articles published until June 2013. Of 3867 screened records, 269 had an acceptable degree of relevance, quality of methodology, and strength of evidence. We found 56 chemical substances with a higher level of evidence and 50 with a moderate level of evidence of causing the above-mentioned disorders. At the first level of the Anatomical Therapeutic Chemical (ATC) classification system, 9 of 14 anatomical groups were represented, mainly the alimentary, cardiovascular, genitourinary, nervous, and respiratory systems. Management strategies include substitution or discontinuation of medications whenever possible, oral or systemic therapy with sialogogues, administration of saliva substitutes, and use of electro-stimulating devices.

LIMITATIONS

While xerostomia was a commonly reported outcome, objectively measured salivary flow rate was rarely reported. Moreover, xerostomia was mostly assessed as an adverse effect rather than the primary outcome of medication use. This study may not include some medications that could cause xerostomia when administered in conjunction with others or for which xerostomia as an adverse reaction has not been reported in the literature or was not detected in our search.

CONCLUSIONS

We compiled a comprehensive list of medications with documented effects on salivary gland function or symptoms that may assist practitioners in assessing patients who complain of dry mouth while taking medications. The list may also prove useful in helping practitioners anticipate adverse effects and consider alternative medications.

β-adrenoceptors as molecular targets in the treatment of hypertension

Regulation of sympathoadrenal activity has been a long-time target in the management of hypertension. Regulation of β-adrenoceptor (βAR) function has been the most therapeutically important of these targets. The development of effective antihypertensive treatments based on βAR antagonism paralleled the elucidation of the molecular basis of β-adrenergic effects by the family of βARs, which are members of the G-protein-coupled receptor (GPCR) superfamily. βARs serve as the extracellular face of the transmembrane signalling pathway that results in the consequent activation of heterotrimeric G-proteins and the activation of several other newly appreciated signalling molecules that include β-arrestins and GPCR kinases (GRKs). The aggregate effect of the activation of these signalling pathways mediates the response to βAR activation. Paradoxically, the hypertensive state is characterized by impaired βAR responsiveness. This defect is common to many other receptor systems linked to the stimulator G protein (Gs) and adenylyl cyclase activation. This impairment is principally mediated by receptor-G-protein uncoupling, which has been linked to increased expression and activity of GRK2.

Regional differences in sexually dimorphic protein expression in the spontaneously hypertensive rat (SHR)

Hypertension is sexually dimorphic and modified by removal of endogenous sex steroids. This study tested the hypothesis that endogenous gonadal hormones exert differential effects on protein expression in the kidney and mesentery of SHR. At ~5 weeks of age male and female SHR underwent sham operation, orchidectomy, or ovariectomy (OVX). At 20-23 weeks of age, mean arterial pressure (MAP) was measured in conscious rats. The mesenteric arterial tree and kidneys were collected, processed for Western blots, and probed for Cu Zn superoxide dismutase (SOD1), soluble epoxide hydrolase (sEH), and Alpha 2A adrenergic receptor (A2AR) expression. MAP was unaffected by ovariectomy (Sham 164 ± 4: Ovariecttomy 159 ± 3 mm Hg). MAP was reduced by orchidectomy (Sham 189 ± 5:Orchidectomy 167 ± 2 mm Hg). In mesenteric artery, SOD1 expression was greater in male versus female SHR. Orchidectomy increased while ovariectomy decreased SOD1 expression. The kidney exhibited a different pattern of response. SOD1 expression was reduced in male compared to female SHR but gonadectomy had no effect. sEH expression was not significantly different among the groups in mesenteric artery. In kidney, sEH expression was greater in males compared to females. Ovariectomy but not orchidectomy increased sEH expression. A2AR expression was greater in female than male SHR in mesentery artery and kidney. Gonadectomy had no effect in either tissue. We conclude that sexually dimorphic hypertension is associated with regionally specific changes in expression of three key proteins involved in blood pressure control. These data suggest that broad spectrum inhibition or stimulation of these systems may not be the best approach for hypertension treatment. Instead regionally targeted manipulation of these systems should be investigated.