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Baby SM, May WJ, Getsy PM, Coffee GA, Nakashe T, Bates JN, Levine A, Lewis SJ. Fentanyl activates opposing opioid and non-opioid receptor systems that control breathing. Front Pharmacol 2024; 15:1381073. [PMID: 38698814 PMCID: PMC11063261 DOI: 10.3389/fphar.2024.1381073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 03/08/2024] [Indexed: 05/05/2024] Open
Abstract
Fentanyl elicits profound disturbances in ventilatory control processes in humans and experimental animals. The traditional viewpoint with respect to fentanyl-induced respiratory depression is that once the effects on the frequency of breathing (Freq), tidal volume (TV), and minute ventilation (MV = Freq × TV) are resolved, then depression of breathing is no longer a concern. The results of the present study challenge this concept with findings, as they reveal that while the apparent inhibitory effects of fentanyl (75 μg/kg, IV) on Freq, TV, and MV in adult male rats were fully resolved within 15 min, many other fentanyl-induced responses were in full effect, including opposing effects on respiratory timing parameters. For example, although the effects on Freq were resolved at 15 min, inspiratory duration (Ti) and end inspiratory pause (EIP) were elevated, whereas expiratory duration (Te) and end expiratory pause (EEP) were diminished. Since the effects of fentanyl on TV had subsided fully at 15 min, it would be expected that the administration of an opioid receptor (OR) antagonist would have minimal effects if the effects of fentanyl on this and other parameters had resolved. We now report that the intravenous injection of a 1.0 mg/kg dose of the peripherally restricted OR antagonist, methyl-naloxone (naloxone methiodide, NLXmi), did not elicit arousal but elicited some relatively minor changes in Freq, TV, MV, Te, and EEP but pronounced changes in Ti and EIP. In contrast, the injection of a 2.5 mg/kg dose of NLXmi elicited pronounced arousal and dramatic changes in many variables, including Freq, TV, and MV, which were not associated with increases in non-apneic breathing events such as apneas. The two compelling conclusions from this study are as follows: 1) the blockade of central ORs produced by the 2.5 mg/kg dose of NLXmi elicits pronounced increases in Freq, TV, and MV in rats in which the effects of fentanyl had apparently resolved, and 2) it is apparent that fentanyl had induced the activation of two systems with counter-balancing effects on Freq and TV: one being an opioid receptor inhibitory system and the other being a non-OR excitatory system.
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Affiliation(s)
- Santhosh M. Baby
- Department of Drug Discovery, Galleon Pharmaceuticals, Inc., Horsham, PA, United States
| | - Walter J. May
- Pediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Paulina M. Getsy
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH, United States
| | - Gregory A. Coffee
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH, United States
| | - Tej Nakashe
- Department of Biological Sciences, Kent State University, Kent, OH, United States
| | - James N. Bates
- Department of Anesthesiology, University of Iowa Hospitals and Clinics, Iowa City, IO, United States
| | - Alan Levine
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, United States
| | - Stephen J. Lewis
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH, United States
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, United States
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Zaros PR, Pires CEMR, Bacci M, Moraes C, Zanesco A. Effect of 6-months of physical exercise on the nitrate/nitrite levels in hypertensive postmenopausal women. BMC WOMENS HEALTH 2009; 9:17. [PMID: 19545388 PMCID: PMC2714506 DOI: 10.1186/1472-6874-9-17] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 06/19/2009] [Indexed: 11/21/2022]
Abstract
Background Evidences have showed that the incidence of arterial hypertension is greater in postmenopausal women as compared to premenopausal. Physical inactivity has been implicated as a major contributor to weight gain and abdominal obesity in postmenopausal women and the incidence of cardiovascular disease increases dramatically after menopause. Additionally, more women than men die each year of coronary heart disease and are twice as likely as men to die within the first year after a heart attack. A healthy lifestyle has been strongly associated with the regular physical activity and evidences have shown that physically active subjects have more longevity with reduction of morbidity and mortality. Nitric oxide (NO) produced by endothelial cells has been implicated in this beneficial effect with improvement of vascular relaxing and reduction in blood pressure in both laboratory animals and human. Although the effect of exercise training in the human cardiovascular system has been largely studied, the majority of these studies were predominantly conducted in men or young volunteers. Therefore, the aim of this work was to investigate the effects of 6 months of dynamic exercise training (ET) on blood pressure and plasma nitrate/nitrite concentration (NOx-) in hypertensive postmenopausal women. Methods Eleven volunteers were submitted to the ET consisting in 3 days a week, each session of 60 minutes during 6 months at moderate intensity (50% of heart rate reserve). Anthropometric parameters, blood pressure, NOx- concentration were measured at initial time and after ET. Results A significant reduction in both systolic and diastolic blood pressure values was seen after ET which was accompanied by markedly increase of NOx- levels (basal: 10 ± 0.9; ET: 16 ± 2 μM). Total cholesterol was significantly reduced (basal: 220 ± 38 and ET: 178 ± 22 mg/dl), whereas triglycerides levels were not modified after ET (basal: 141 ± 89 and ET: 147 ± 8 mg/dl). Conclusion Our study shows that changing in lifestyle promotes reduction of arterial pressure which was accompanied by increase in nitrite/nitrate concentration. Therefore, 6-months of exercise training are an important approach in management arterial hypertension and play a protective effect in postmenopausal women.
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Affiliation(s)
- Pedro R Zaros
- Department of Physical Education, Institute of Biosciences, University of Sao Paulo State (UNESP), Rio Claro (SP), Brazil.
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Pesini P, Rois JL, Menéndez L, Vidal S. The Neonatal Treatment of Rats with Monosodium Glutamate Induces Morphological Changes in the Subfornical Organ. Anat Histol Embryol 2004; 33:273-7. [PMID: 15352879 DOI: 10.1111/j.1439-0264.2004.00547.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The parenteral administration of monosodium glutamate (MSG) to neonatal rats induces specific lesions in the central nervous system that lead to a well characterized neuroendocrinological dysfunction. Additionally, it has been shown that MSG-treated rats present a blunted blood pressure response to the injection of nitric oxide synthase inhibitors. Recently, a similar cardiovascular alteration has been reported after the electrolytic lesion of the anteroventral region of the third ventricle affecting the connections of the subfornical organ (SFO). We hypothesized that the treatment of neonatal rats with MSG could affect the nitrergic cells of the SFO. In the present work, we have looked for alterations in the NADPH-diaphorase activity (a commonly used marker for nitrergic neurons) in the SFO of MSG-treated rats of either sex and at two different ages. Our results shown that the treatment of neonatal rats with MSG induced a substantial reduction in the volume of the SFO and in the number of its nitrergic cells with regard to control animals. These findings suggest that the SFO could be implicated in some of the cardiovascular alterations observed in MSG-treated rats.
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Affiliation(s)
- P Pesini
- Department of Anatomy, Faculty of Veterinary Medicine, University of Santiago, 27002 Lugo, Spain.
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