Cardiovascular responses to intrathecal neuropeptide γ in conscious rats: receptor characterization and mechanism of action

Poulat, P.; Champlain, Jacques de; Couture, Réjean

doi:10.1111/j.1476-5381.1996.tb15184.x

Cited by 12 publications

(6 citation statements)

References 55 publications

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“…Their maximal changes elicited by i.v. injections of increasing bolus (100 μ L) doses of EOOG (1–20 mg/kg) were determined in conscious rats which had been pretreated intravenously 10 min earlier with vehicle (1 mL/kg, n = 9) or propranolol (2 mg/kg, n = 6) [18–20]. When subsequent doses of EOOG were administered, MAP and HR were first allowed to return to their baseline levels, obtained before the first injection of the essential oil.…”

Section: Methodsmentioning

confidence: 99%

Pharmacological evidence of calcium‐channel blockade by essential oil of Ocimum gratissimum and its main constituent, eugenol, in isolated aortic rings from DOCA‐salt hypertensive rats

Interaminense

Jucá

Magalhães

et al. 2007

Fundamemntal Clinical Pharma

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Intravenous (i.v.) treatment of conscious DOCA-salt hypertensive rats with the essential oil of Ocimum gratissimum L. (Labiatae) (EOOG) induced a hypotensive effect that seems related to an active vascular relaxation rather than withdrawal of sympathetic tone. To corroborate this hypothesis, the present study examined the vascular effects of EOOG and its main constituent, eugenol (EUG) and the putative mechanisms underlying these effects. Additionally, the role of the vascular beta(2)-adrenergic mechanism in the mediation of EOOG-induced hypotension has also been investigated. In conscious DOCA-salt hypertensive rats, the EOOG-induced hypotension was reversible and remained unchanged by i.v. pretreatment with propranolol (2 mg/kg). In isolated aorta preparations with intact endothelium from DOCA-salt hypertensive rats, EOOG (1-1000 microg/mL) and EUG (0.006-6 mM) relaxed the phenylephrine-induced contraction similarly with IC(50) [geometric mean (95% confidence interval)] values of 226.9 (147.8-348.3) microg/mL and 1.2 (0.6-2.1) mm, respectively. Vasorelaxant effects of EOOG were significantly altered by removal of the vascular endothelium [IC(50) = 417.2 (349.5-497.8) microg/mL]. In a calcium-free medium, the CaCl(2)-induced contractions were significantly reduced and even abolished by EOOG at 300 and 1000 microg/mL, respectively, whereas EOOG (1000 microg/mL) did not have any significant effect on caffeine-induced contractions. Similar results were obtained with EUG (1.8 and 6 mM) on both CaCl(2)- and caffeine-induced contractions, respectively. The data suggest that hypotensive responses to EOOG in DOCA-salt hypertensive rats are due to an active vascular relaxation, which is partly dependent upon the integrity of the vascular endothelium and seems predominantly mediated through an inhibition of plasmalemmal Ca(2+) influx rather than Ca(2+)-induced Ca(2+) release from the sarcoplasmic reticulum.

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Section: Methodsmentioning

confidence: 99%

Pharmacological evidence of calcium‐channel blockade by essential oil of Ocimum gratissimum and its main constituent, eugenol, in isolated aortic rings from DOCA‐salt hypertensive rats

Interaminense

Jucá

Magalhães

et al. 2007

Fundamemntal Clinical Pharma

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“…Three minutes later, and 7 min before the second injection of EOCZ (10 mg/kg, i.a. ), the NK 1 ‐selective antagonist RP 67580 (7.8 nmol; at the L5–L6 level; 32 n = 7) or its vehicle ( n = 3) was administered i.t. and the maximal MAP and HR changes were again determined.…”

Section: Methodsmentioning

confidence: 99%

ROLE OF CAPSAICIN‐SENSITIVE SENSORY NERVES IN MEDIATION OF THE CARDIOVASCULAR EFFECTS OF THE ESSENTIAL OIL OF CROTON ZEHNTNERI LEAVES IN ANAESTHETIZED RATS

Siqueira

Leal‐Cardoso

Couture

et al. 2006

Clin Exp Pharma Physio

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The essential oil of Croton zehntneri Pax et Hoffm. (EOCZ) contains anethole (42%) and estragole (46%), two isomers that share some chemical structural similarities with capsaicin. The present study investigated the cardiovascular effects of EOCZ and the role of capsaicin-sensitive sensory nerve fibres in the mediation of these effects in anaesthetized rats. 2. Intravenous bolus injection of EOCZ (1-20 mg/kg) elicited dose-dependent hypotension and bradycardia that were immediate and transient. Similar responses were also observed with anethole and estragole (both at 10 mg/kg). After cervical bivagotomy or perineural treatment of both cervical vagus nerves with capsaicin (250 mg/mL) to selectively block the conduction of sensory C-fibres, both cardiovascular responses to EOCZ (10 mg/kg) were abolished. 3. Like capsaicin, an epigastric retrograde intra-arterial injection of EOCZ (10 mg/kg, i.a.) into the femoral artery elicited a monophasic hypotensive response. This reflex response was blocked by either neonatal pretreatment with capsaicin (50 mg/kg, s.c.) or intrathecal injection of the substance P receptor antagonist RP 67580 (7.8 nmol, at the spinal level L5-L6), suggesting that it is mediated exclusively by substance P-containing primary afferent fibres. 4. The cardiovascular responses to EOCZ (10 mg/kg, i.v.) were also significantly reduced by the selective vallinoid TPRV1 receptor antagonist capsazepine (1 mg/kg, i.v.). 5. It is concluded that i.v. administration of EOCZ in anaesthetized rats elicits a capsaicin-like bradycardic and depressor reflex, which appears to be mediated by the activation of vallinoid TPRV1 receptors located on vagal sensory nerves. Like capsaicin, i.a. injection of EOCZ induces a spinally mediated sensory reflex.

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“…In contrast, the central actions of NPK were mediated solely by the NK1 receptor as no residual responses were observed when NPK was pretreated with RP 67,580 (6.5 nmol) in a protocol similar to the present study (Prat et al, 1994 (Unger et al, 1981;1985;Takano et al, 1990), while those induced by i.c.v. injection of NK3 agonists would result mainly from the release of vasopressin from the hypothalamus and to a minor extent by activation of the sympathetic nervous system (Polidori et al, 1989;Takano et al, 1990;1993 (Poulat et al, 1996). The hypothalamus may be the site of action of tachykinins since microinjections of SP into the anterior, ventromedial and medial preoptic parts of the hypothalamus of the awake unrestrained rat evoked cardiovascular and behavioural changes similar to those produced by i.c.v.…”

Section: Discussionmentioning

confidence: 99%

“…These effects on lung functions and human bronchus were inhibited by SR 48,968, suggesting that NPy exerts its effects via NK2 receptors (Qian et al, 1994;Yuan et al, 1994). On the other hand, when administered intrathecally (T-9 level) in the conscious rat, NPy (78 pmol-78 nmol) induced dose-dependent increases in heart rate and mean arterial blood pressure; these British Journal of Pharmacology (1996) 117,[241][242][243][244][245][246][247][248][249] effects were blocked by RP 67,580 (selective NKI receptor antagonist), but not by SR 48,968 or R 486 (selective NK3 antagonist) (Poulat et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

Intracerebroventricular responses to neuropeptide γ in the conscious rat: characterization of its receptor with selective antagonists

Picard

Couture

1996

British J Pharmacology

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Cardiovascular responses to intrathecal neuropeptide γ in conscious rats: receptor characterization and mechanism of action

Cited by 12 publications

References 55 publications

Pharmacological evidence of calcium‐channel blockade by essential oil of Ocimum gratissimum and its main constituent, eugenol, in isolated aortic rings from DOCA‐salt hypertensive rats

Pharmacological evidence of calcium‐channel blockade by essential oil of Ocimum gratissimum and its main constituent, eugenol, in isolated aortic rings from DOCA‐salt hypertensive rats

ROLE OF CAPSAICIN‐SENSITIVE SENSORY NERVES IN MEDIATION OF THE CARDIOVASCULAR EFFECTS OF THE ESSENTIAL OIL OF CROTON ZEHNTNERI LEAVES IN ANAESTHETIZED RATS

Intracerebroventricular responses to neuropeptide γ in the conscious rat: characterization of its receptor with selective antagonists

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