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Lamptey RNL, Sun C, Layek B, Singh J. Neurogenic Hypertension, the Blood-Brain Barrier, and the Potential Role of Targeted Nanotherapeutics. Int J Mol Sci 2023; 24:ijms24032213. [PMID: 36768536 PMCID: PMC9916775 DOI: 10.3390/ijms24032213] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/13/2023] [Accepted: 01/16/2023] [Indexed: 01/26/2023] Open
Abstract
Hypertension is a major health concern globally. Elevated blood pressure, initiated and maintained by the brain, is defined as neurogenic hypertension (NH), which accounts for nearly half of all hypertension cases. A significant increase in angiotensin II-mediated sympathetic nervous system activity within the brain is known to be the key driving force behind NH. Blood pressure control in NH has been demonstrated through intracerebrovascular injection of agents that reduce the sympathetic influence on cardiac functions. However, traditional antihypertensive agents lack effective brain permeation, making NH management extremely challenging. Therefore, developing strategies that allow brain-targeted delivery of antihypertensives at the therapeutic level is crucial. Targeting nanotherapeutics have become popular in delivering therapeutics to hard-to-reach regions of the body, including the brain. Despite the frequent use of nanotherapeutics in other pathological conditions such as cancer, their use in hypertension has received very little attention. This review discusses the underlying pathophysiology and current management strategies for NH, as well as the potential role of targeted therapeutics in improving current treatment strategies.
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Affiliation(s)
| | | | - Buddhadev Layek
- Correspondence: (B.L.); (J.S.); Tel.: +1-701-231-7906 (B.L.); +1-701-231-7943 (J.S.); Fax: +1-701-231-8333 (B.L. & J.S.)
| | - Jagdish Singh
- Correspondence: (B.L.); (J.S.); Tel.: +1-701-231-7906 (B.L.); +1-701-231-7943 (J.S.); Fax: +1-701-231-8333 (B.L. & J.S.)
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HANSSON L. CLINICAL ASPECTS OF BLOOD PRESSURE CRISIS DUE TO WITHDRAWAL OF CENTRALLY ACTING ANTIHYPERTENSIVE DRUGS. Br J Clin Pharmacol 2012. [DOI: 10.1111/j.1365-2125.1983.tb00315.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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WEVER A, BRUMMELEN P. THE INFLUENCE OF GUANFACINE ON BLOOD PRESSURE AND LUNG FUNCTION IN HYPERTENSIVE PATIENTS WITH CHRONIC OBSTRUCTIVE LUNG DISEASE. Br J Clin Pharmacol 2012. [DOI: 10.1111/j.1365-2125.1983.tb00318.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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ZWIETEN P, THOOLEN M, TIMMERMANS P. THE PHARMACOLOGY OF CENTRALLY ACTING ANTIHYPERTENSIVE DRUGS. Br J Clin Pharmacol 2012. [DOI: 10.1111/j.1365-2125.1983.tb00311.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Abstract
The classic centrally acting antihypertensives such as clonidine, guanfacine and alpha-methyl-DOPA (via its active metabolite alpha-methyl-noradrenaline) induce peripheral sympathoinhibition and a fall in blood pressure as a result of alpha2-adrenoceptor stimulation in the brain stem. These drugs have lost much of their clinical importance because of their unfavourable side-effects (sedation, dry mouth, impotence), which are also mediated by alpha2-adrenoceptors, although in other anatomical regions. Moxonidine and rilmenidine are the examples of a new class of centrally acting antihypertensives, which cause peripheral sympathoinhibition mediated by imidazoline (I1)-receptors in the rostral ventromedulla (RVLM). Their side-effect profile appears to be better than that of clonidine and alpha-methyl-DOPA, probably because of a weaker affinity for alpha2-adrenoceptors. The mode of action, haemodynamic profile, antihypertensive efficacy and adverse reactions of the classic and newer centrally acting antihypertensives are the subject of the present survey. Attention is also paid to other therapeutic applications of centrally acting antihypertensives, such as congestive heart failure and the metabolic syndrome.
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Affiliation(s)
- P A van Zwieten
- Department of Pharmacotherapy, Academic Medical Centre, University of Amsterdam, The Netherlands
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Grubb MC, Stornetta RL, Pence R, Baertschi AJ, Guyenet PG. Antagonist precipitated clonidine withdrawal in rat: effects on locus coeruleus neurons, sympathetic nerves and cardiovascular parameters. JOURNAL OF THE AUTONOMIC NERVOUS SYSTEM 1998; 71:85-95. [PMID: 9760045 DOI: 10.1016/s0165-1838(98)00065-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The goal of the present study was to examine the effect of clonidine withdrawal on the neural control of blood pressure. Rats were treated for 7-13 days with clonidine via osmotic minipumps (200 microg kg(-1) day(-1), s.c.). Controls received saline or were sham operated. Withdrawal was precipitated by the alpha2-adrenergic receptor (alpha2-AR) antagonist atipamezole. Most experiments were done under halothane anesthesia. Chronic treatment with clonidine did not change mean arterial pressure (MAP) or heart rate (HR) but raised femoral artery resistance and the activity of locus coeruleus neurons slightly. Atipamezole given to rats treated chronically with clonidine produced the following effects: no change in MAP, severe tachycardia, sustained increase in splanchnic sympathetic nerve discharge (SND; +75 +/- 13%), transient increase in lumbar SND (+23 +/- 7%), ON-OFF activity pattern in the locus coeruleus (LC). The ON phase of LC activity was synchronized with upswings of SND and with small changes in MAP. A second alpha2-AR antagonist, methoxyidazoxan, produced effects identical to those of atipamezole. Atipamezole given to control rats produced no effect on MAP, HR, SND or LC activity. Atipamezole reversed the hypotension, sympathoinhibition and bradycardia produced by acute administration of clonidine. In awake rats treated chronically with clonidine, atipamezole did not change MAP but produced arterial pressure lability and tachycardia. In conclusion, under anesthesia, selective alpha2-AR antagonists elicit a clonidine withdrawal syndrome that displays autonomic characteristics reminiscent of the spontaneous withdrawal syndrome found in awake rats. The most prominent features of this syndrome are tachycardia, sympathoactivation, lack of hypertension and an oscillating activity pattern of brainstem neurons leading to abrupt changes in SND and in MAP.
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Affiliation(s)
- M C Grubb
- Department of Behavioral Neuroscience, Oregon Health Sciences University, Portland 97201, USA
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Marona-Lewicka D, Nichols DE. Complex stimulus properties of LSD: a drug discrimination study with alpha 2-adrenoceptor agonists and antagonists. Psychopharmacology (Berl) 1995; 120:384-91. [PMID: 8539318 DOI: 10.1007/bf02245809] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The influence of several alpha 2-adrenergic agents on the discriminative stimulus (DS) properties of lysergic acid diethylamide (LSD) was studied in rats trained to discriminate 0.08 mg/kg (186 nmol/kg) of LSD from saline in a two-lever operant paradigm. Only yohimbine fully mimicked LSD with an ED50 of 2.05 mg/kg (5.24 mumol/kg). Yohimbine's 5-HT1A agonist properties may be responsible for this substitution. Other alpha 2-adrenoceptor antagonists, idazoxan with an agonist/antagonist profile at 5-HT1A receptors and RS 26026-197, a highly selective alpha 2-adrenoceptor antagonist, failed to produce substitution. Clonidine, an alpha 2-adrenoceptor agonist, did not substitute for LSD but the response rate was dose-dependently reduced. None of the alpha 2-adrenergic agents used for pretreatment before LSD inhibited the response to the LSD training dose. Coadministration of clonidine with LSD produced a leftward shift of the dose-response relationship of LSD without a significant change in the slope of the dose-response line. Simultaneous administration of alpha 2-adrenergic agents with LSD shifted the dose-response curve to the left only when the adrenergic agent also possessed at least moderate affinity for the 5-HT1A receptor. In addition, radioligand competition experiments were performed that showed LSD to have relatively high affinity (Ki = 37 nM) for [3H]clonidine-labeled sites in rat cortex with lower affinity for [3H]yohimbine labeled sites. While previous studies have suggested that the nature of the LSD cue may be essentially expressed by 5-HT2 receptor activation, the present data show that this cue can be modulated by effects of LSD at 5-HT1A and at other monoamine neurotransmitter receptors.
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Affiliation(s)
- D Marona-Lewicka
- Department of Pharmacology and Toxicology, School of Pharmacy and Pharmacal Sciences, Purdue University, West Lafayette, IN 47907, USA
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Abstract
Major advances have been made in our understanding of the molecular structure and function of the alpha-adrenoceptors. Many new subtypes of the alpha-adrenoceptor have been identified recently through biochemical and pharmacological techniques and several of these receptors have been cloned and expressed in a variety of vector systems. Currently, at least seven subtypes of the alpha-adrenoceptor have been identified and the molecular structure and biochemical functions of these subtypes are beginning to be understood. The alpha-adrenoceptors belong to the super family of receptors that are coupled to guanine nucleotide regulatory proteins (G-proteins). A variety of G-proteins are involved in the coupling of the various alpha-adrenoceptor subtypes to intracellular second messenger systems, which ultimately produce the end-organ response. The mechanisms by which the alpha-adrenoceptor subtypes recognize different G-proteins, as well as the molecular interactions between receptors and G-proteins, are the topics of current research. Furthermore, the physiological and pathophysiological role that alpha-adrenoceptors play in homeostasis and in a variety of disease states is also being elucidated. These major advances made in alpha-adrenoceptor classification, molecular structure, physiologic function, second messenger systems and therapeutic relevance are the subject of this review.
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Affiliation(s)
- R R Ruffolo
- Department of Pharmacology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406
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Ruffolo RR, Hieble JP, Brooks DP, Feuerstein GZ, Nichols AJ. Drug receptors and control of the cardiovascular system: recent advances. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1991; 36:117-360. [PMID: 1876708 DOI: 10.1007/978-3-0348-7136-5_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- R R Ruffolo
- SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406
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Recent Experimental and Conceptual Advances in Drug Receptor Research in the Cardiovascular System. ACTA ACUST UNITED AC 1988. [DOI: 10.1016/b978-0-12-013317-8.50007-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Ruffolo RR, Nichols AJ, Hieble JP. Functions Mediated by alpha-2 Adrenergic Receptors. THE ALPHA-2 ADRENERGIC RECEPTORS 1988. [DOI: 10.1007/978-1-4612-4596-4_5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Ben-Zvi Z, Graham CE, Hurwitz A. Tolerance to effects of clonidine and morphine on sulfobromophthalein disposition in mice. Life Sci 1987; 40:1617-23. [PMID: 3561168 DOI: 10.1016/0024-3205(87)90128-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Chronic treatment of mice with clonidine or morphine caused tolerance to the analgesic and thermoregulatory effects of these drugs. After chronic morphine, mice also became tolerant to the analgesic and thermoregulatory effects of clonidine. Cross tolerance to the hypothermic effect of morphine was demonstrated after chronic clonidine administration, but no diminution of morphine-induced analgesia could be shown. Morphine and clonidine acutely increased the retention of sulfobromophthalein (BSP) in plasma and liver. Chronic dosing with morphine or clonidine caused partial tolerance and cross-tolerance to the rise in hepatic BSP caused by an acute challenge with either agonist. However, both drugs elevated plasma BSP levels similarly in tolerant and non-tolerant mice. Thus, regimens which readily induced tolerance to the analgesic and hypothermic effects of morphine or clonidine were only partially effective in modifying the acute hepatobiliary effects of these drugs.
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Jonkman FA, Man PW, Thoolen MJ, van Zwieten PA. Location of the mechanism of the clonidine withdrawal tachycardia in rats. J Pharm Pharmacol 1985; 37:580-2. [PMID: 2864424 DOI: 10.1111/j.2042-7158.1985.tb03074.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Withdrawal of chronic infusion of clonidine elicits severe tachycardia and short-lasting blood pressure elevations (upswings). Withdrawal of clonidine in low dosage (30 micrograms kg-1 day-1 i.c.v., 7 days) elicited a maximum of 10.9 +/- 0.5 upswings h-1. Cessation of s.c. infusion of clonidine (30 micrograms kg-1 day-1 7 days) evoked a maximum of 1.9 +/- 0.5 upswings h-1. After cessation of the two clonidine infusions no overshoot of heart rate occurred. Withdrawal of a higher dose of clonidine (300 micrograms kg-1 day-1 s.c., 7 days), however, induced tachycardia (from 302 +/- 8 to 433 +/- 8 beats min-1) and 7.6 +/- 1.4 upswings h-1. The administration of the alpha 2-adrenoceptor antagonist yohimbine precipitated withdrawal tachycardia in animals treated with oxymetazoline, a hydrophilic alpha-adrenoceptor agonist. Yohimbine (3 mg kg-1 i.p.) precipitated a severe rise in heart rate from 285 +/- 14 to 520 +/- 5 beats min-1 in oxymetazoline (300 micrograms kg-1 day-1 s.c., 7 days) treated rats and from 320 +/- 13 to 420 +/- 11 beats min-1 in saline-treated animals. Upswings were not induced by yohimbine treatment. It is concluded, that the blood pressure upswings after clonidine withdrawal are due to a central mechanism, whereas the mechanism of the overshoot of heart rate is located peripherally, probably at the cardiac presynaptic level.
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Abstract
The dependence-inducing effects of clonidine were investigated on the guinea-pig isolated ileum. Clonidine produced relaxation of the ileum with a threshold concentration between 0.01 and 0.1 mumol 1(-1). Washout of clonidine did not induce a withdrawal contraction. Following 2 min contact of the ileum with clonidine, 1 mumol 1(-1), addition of phentolamine, 5 mumol 1(-1), induced a contracture. The phentolamine-precipitated withdrawal contracture did not increase in height with a longer period of contact (32 min) of the ileum with clonidine. The phentolamine-precipitated withdrawal contracture following 2 min contact of ileum with clonidine was abolished by atropine, 5 mumol 1(-1), and substance P (SP) antagonists, (D-Pro2,D-Phe7, D-Trp9)-SP and spantide, 10 mumol 1)-1). [Met5]enkephalin, 1 mumol 1(-1), abolished the withdrawal response to clonidine and clonidine, 1 mumol 1(-1), abolished the withdrawal response to [Met5]enkephalin. Following 2 min contact of the ileum with noradrenaline, 5 mumol 1(-1), washout or addition of phentolamine or yohimbine, 5 mumol 1(-1), also induced a withdrawal response. The noradrenaline washout withdrawal response was abolished by atropine, 5 mumol 1(-1), and spantide, 10 mumol 1(-1). Since clonidine dependence may be induced as rapidly as opiate dependence in the ileum and the pharmacology of the withdrawal responses is similar, it is suggested that they both induce the same post-receptor neuronal feedback disturbance in which substance P neurones play a major role.
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POSTER COMMUNICATIONS. Br J Pharmacol 1985. [DOI: 10.1111/j.1476-5381.1985.tb17369.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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van Zwieten PA, Thoolen MJ, Timmermans PB. The hypotensive activity and side effects of methyldopa, clonidine, and guanfacine. Hypertension 1984; 6:II28-33. [PMID: 6094346 DOI: 10.1161/01.hyp.6.5_pt_2.ii28] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Clonidine (Catapres, Catapresan), guanfacine (Estulic), and methyldopa (Aldomet) are the prototypes of centrally acting antihypertensive drugs. Clonidine and guanfacine are lipophilic drugs that readily penetrate into the brain, where they stimulate alpha-adrenergic receptors in the pontomedullary region. The stimulation of these central alpha-adrenergic receptors has been shown to activate an inhibiting neuron, which causes a reduction of peripheral sympathetic tone and a subsequent fall in arterial blood pressure and heart rate. Both a centrally initiated reduction of vagus reflex activity and the activation of presynaptic alpha 2-adrenergic blocking agents in the heart may contribute to the bradycardia. Studies indicate that methyldopa also penetrates into the brain, where it is converted into alpha-methylnorepinephrine. This amine may stimulate the same central alpha-adrenergic receptors as those activated by clonidine, which will result in a hypotensive effect. Possibly, alpha-methyldopamine might also play a role. Accordingly, the modes of action of clonidine and alpha-methyldopa probably are very similar at a basic level. The central adrenergic receptors probably are located postsynaptically. Their receptor demand corresponds more closely to that of the alpha 2-subtype. Central alpha 1-adrenergic receptors might possibly play a part in the modulation of vagally induced baroreflex bradycardia. A discussion on the pharmacological basis of the side effects of the centrally acting antihypertensives has been limited to those adverse reactions that are somehow related to alpha-adrenergic receptors. Sedation, a common side effect, appears to be mediated by central alpha 2-adrenergic receptors, at least in animal models.(ABSTRACT TRUNCATED AT 250 WORDS)
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Jonkman FA, Thoolen MJ, Wilffert B, de Jonge A, Timmermans PB, Van Zwieten PA. Effect of salbutamol and the PDE-inhibitor RA 642 on the clonidine withdrawal syndrome in rats. JOURNAL OF AUTONOMIC PHARMACOLOGY 1984; 4:199-206. [PMID: 6092386 DOI: 10.1111/j.1474-8673.1984.tb00097.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The effect of continuous subcutaneous infusion of clonidine and the influence of concomitant treatment with salbutamol as well as the acute effects of the PDE-inhibitor RA 642 on heart rate and blood pressure of conscious normotensive rats were studied. The severity of the cardiovascular clonidine withdrawal symptoms was positively related to the amount of clonidine infused during treatment. Concomitant infusion of salbutamol (12 mg/kg/day) and clonidine (300 microgram/kg/day) attenuated the clonidine withdrawal tachycardia in conscious normotensive rats. No difference existed in the isoprenaline induced tachycardia in pithed normotensive rats, 8-14 h after cessation of infusion with clonidine (300 microgram/kg/day) and saline, clonidine and salbutamol (12 mg/kg/day), or saline alone. The PDE-inhibitor RA 642 (12 mg/kg, i.p.) aggravated the clonidine withdrawal syndrome in conscious normotensive rats. These data may indicate that long-term treatment with clonidine induces a hyperactivation of the adenylate-cyclase/cAMP-system.
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