1
|
Ahmed N, Kassis A, Malone J, Yang J, Zamzami E, Lin AH, Gordon SM, Gong M, Bardo M, Dalmasso C, Loria AS. Prenatal Morphine Exposure Increases Cardiovascular Disease Risk and Programs Neurogenic Hypertension in the Adult Offspring. Hypertension 2023; 80:1283-1296. [PMID: 37042247 PMCID: PMC10274123 DOI: 10.1161/hypertensionaha.122.20262] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 03/20/2023] [Indexed: 04/13/2023]
Abstract
BACKGROUND The opioid overdose and opioid use disorder epidemics are concomitant with increased metabolic and CVD risk. Although opioid use disorder causes adverse pregnancy outcomes, the offspring's cardiovascular health is understudied. We hypothesized that offspring exposed to in utero morphine exposure (IUME) would show increased CVD risk factors and endogenous opioid system dysregulation. METHODS Sprague Dawley dams were treated with saline (vehicle, n=10) or escalating doses of morphine (5-20 mg/kg per day, SC, n=10) during gestation. Cardiovascular and metabolic parameters were assessed in adult offspring. RESULTS Litter size and pups' birth weight were not different in response to IUME. Female and male IUME offspring showed reduced body length at birth (P<0.05) and body weight from weeks 1 to 3 of life (P<0.05), followed by a catch-up growth effect. By week 16, female and male IUME rats showed reduced tibia length (P<0.05) and fat mass. IUME increases the mean arterial pressure and the depressor response to mecamylamine (5 mg/kg per day, IP) induced by IUME were abolished by a chronic treatment with an alpha-adrenergic receptor blocker (prazosin; 1 mg/kg per day, IP). Although circulating levels of angiotensin peptides were similar between groups, IUME exacerbated maximal ex vivo Ang (angiotensin) II-induced vasoconstriction (P<0.05) and induced endothelial dysfunction in a sex-specific manner (P<0.05). Proenkephalin, an endogenous opioid peptide that lowers blood pressure and sympathetic-mediated vasoconstriction, showed reduced mRNA expression in the heart, aorta, and kidneys from morphine versus vehicle group (P<0.05). CONCLUSIONS Among the effects of IUME, neurogenic hypertension, vascular dysfunction, and metabolic dysfunction could be associated with the dysregulation of the endogenous opioid system.
Collapse
Affiliation(s)
- Nermin Ahmed
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536
| | - Alana Kassis
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536
| | - Jena Malone
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536
| | - Jodie Yang
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536
| | - Esraa Zamzami
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536
| | - An-Hsuan Lin
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536
| | - Scott M. Gordon
- SAHA Cardiovascular Center, University of Kentucky, Lexington, KY 40536
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536
| | - Ming Gong
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536
| | - Michael Bardo
- Department of Psychology, College of Arts and Sciences, University of Kentucky, Lexington, KY 40536
| | - Carolina Dalmasso
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536
| | - Analia S. Loria
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536
- SAHA Cardiovascular Center, University of Kentucky, Lexington, KY 40536
| |
Collapse
|
2
|
Alkadhi K, Alzoubi K. Role of long-term potentiation of sympathetic ganglia (gLTP) in hypertension. Clin Exp Hypertens 2007; 29:267-86. [PMID: 17653963 DOI: 10.1080/10641960701500356] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Ganglionic long-term potentiation (gLTP) is an activity-dependent sustained increase in the synaptic efficacy of the nicotinic pathway that has been demonstrated in autonomic ganglia. Sustained enhancement in ganglionic transmission as in chronic mental stress may affect the activity of autonomic functions, including blood pressure and heart rate. An increase in sympathetic activity associated with psychosocial stress and stress-prone conditions such as obesity and aging could result in in vivo expression of gLTP leading to hypertension of a neural origin. Recent reports indicated that the prevention of the expression of gLTP in animal models of hypertension prevented or reduced high blood pressure. Although stress-induced hypertension normalizes within a few days of stress relief, prolonged mild-moderate hypertension may contribute to atherosclerotic cardiovascular diseases. The relation between hypertension and enhanced ganglionic transmission as a result of in vivo expression of gLTP is discussed in this review.
Collapse
Affiliation(s)
- Karim Alkadhi
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas 77204-5515, USA.
| | | |
Collapse
|
3
|
Barnes MJ, Jen KLC, Dunbar JC. The effect of CNS opioid on autonomic nervous and cardiovascular responses in diet-induced obese rats. Peptides 2004; 25:71-9. [PMID: 15003358 DOI: 10.1016/j.peptides.2003.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2003] [Accepted: 11/07/2003] [Indexed: 12/26/2022]
Abstract
The intracerebroventricular (i.c.v.) infusion of beta-endorphin can cause either a decrease in blood pressure in normal rats or an increase in obese rats. Diet-induced obesity is associated with an increase of hypothalamic mu opioid receptors. Since beta-endorphins act by opioid receptors, we investigated the effect of CNS mu as well as kappa opioid receptor agonist and antagonist on mean blood pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) in male Wistar rats fed either a high fat (HF) (40% fat by weight) or a regular low fat (control) (4% fat by weight) diet. After a 12-week-feeding period the animals were implanted with i.c.v. cannulas and 3-5 days later they were anesthetized and instrumented to record MAP, HR and RSNA. HF rats have higher MAP and the i.c.v. injection of a mu opioid agonist (DAMGO) initially decreased the MAP and then increased MAP, HR and RSNA in the normal animals. The increase was greater in HF animals. The i.c.v. injection of the mu antagonist (beta-FNA) resulted in a significantly greater decrease in MAP in HF animals. beta-FNA increased the RSNA in the HF rats but decreased it in the normal rats. The kappa agonist (dynorphin) decreased MAP in normal rats followed by a return to baseline, but not in HF rats. The kappa antagonist, nor-binaltorphimine (N-BP), increased MAP and RSNA in normal rats and to a lesser extent in HF rats. These findings suggest that rats given a high fat diet have higher blood pressures and a greater mu opioid-mediated responsiveness with a greater mu opioid-mediated autonomic tone. Additionally there is a decreased kappa responsiveness and tone in the HF rats. Both these changes, increased mu and decreased kappa responsiveness could strongly contribute to the increased blood pressure in obese animals.
Collapse
MESH Headings
- Animals
- Blood Pressure
- Body Weight
- Central Nervous System/drug effects
- Diet
- Dose-Response Relationship, Drug
- Dynorphins/administration & dosage
- Dynorphins/metabolism
- Dynorphins/pharmacology
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/administration & dosage
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/metabolism
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Male
- Obesity/physiopathology
- Rats
- Rats, Wistar
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/metabolism
- Time Factors
Collapse
Affiliation(s)
- Maria J Barnes
- Department of Nutrition and Food Science, Wayne State University, Detroit, MI 48201-1928, USA
| | | | | |
Collapse
|
4
|
Barnes MJ, Lapanowski K, Conley A, Rafols JA, Jen KLC, Dunbar JC. High fat feeding is associated with increased blood pressure, sympathetic nerve activity and hypothalamic mu opioid receptors. Brain Res Bull 2003; 61:511-9. [PMID: 13679250 DOI: 10.1016/s0361-9230(03)00188-6] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Obesity and high fat diets are associated with an increased prevalence of diabetes, cardiovascular disease, and hypertension. However, the mechanism(s) linking obesity and high fat diet to these metabolic and cardiovascular disorders are not fully elucidated. Leptin stimulates the formation of pro-opiomelanocortin and its products. The stimulation of the central nervous system (CNS) opioids and their receptors is associated with an increase in cardiovascular dynamics. In this study we hypothesized that obesity changed the CNS opioids and their receptors that could play a role in altered cardiovascular and autonomic nervous regulation in obesity. Male Wistar rats were fed either a high fat (HF) or regular chow (control) diet. After 12 weeks, rats were anesthetized and instrumented to record mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA). A blood sample was collected and plasma glucose, insulin, leptin, beta-endorphins were measured. The brains were subsequently processed for immunohistochemistry and in situ hybridization. The HF rats were larger and had a greater percentage of body fat. Leptin and insulin levels were also higher in the HF animals. Basal MAP and RSNA were significantly higher in HF rats. Additionally, immunohistochemistry and in situ hybridization demonstrated that HF rats had increased hypothalamus mu opioid receptors compared to controls. These studies suggest that HF feeding is associated with increased body fat, plasma leptin, insulin, and hypothalamic mu opioid receptors. The increased mu opioid receptors may contribute to the higher MAP and RSNA observed in HF animals.
Collapse
Affiliation(s)
- Maria J Barnes
- Department of Nutrition and Food Science, Wayne State University, Detroit, MI 48201-1928, USA
| | | | | | | | | | | |
Collapse
|
5
|
Shen S, Ingenito AJ. Depressor effect of kappa opioid agonist on hypertension induced by isolation in the rat. Clin Exp Hypertens 1999; 21:275-97. [PMID: 10225482 DOI: 10.3109/10641969909068667] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Previous studies by us established that peripheral and hippocampal administration of kappa opioid receptor agonists lowered blood pressure (BP) in the spontaneously hypertensive rat (SHR). The object of the present study was to determine whether U62,066E, a non-peptide kappa agonist, would lower BP in another animal model of hypertension; that produced by isolation of young male rats. After 7 days of isolation had produced a sustained hypertension of approximately 40 mmHg, drug effects were determined in the isolated hypertensive animals and group-housed normotensive rats. Two drug-treated plus vehicle control groups were used as follows: (1) 2 mg/kg intraperitoneally twice daily for 3 days in conscious animals and (2) intrahippocampal injection of from 1 to 10 nmol in animals anesthetized with chloralose and pentobarbital. In group (1) the drug lowered both systolic BP (SBP) and mean BP (MBP) nearly to pre-isolation levels, while having no significant effect on these parameters in group-housed normotensive controls. Heart rate (HR) was not significantly affected by the drug in either sub-group. In group (2) SBP, MBP and HR were reduced in both the isolated hypertensive and group-housed normotensive animals when the drug was given intrahippocampally at 5.0 nmol. The depressor response to intrahippocampal U-62,066E was dose-related in both isolated and grouped rats at doses ranging from 1 to 10 nmol. The findings support our earlier suggestions that the hippocampal kappa opioid system may be somehow involved in cardiovascular regulation and that the non-peptide kappa agonists might make effective antihypertensive drugs.
Collapse
Affiliation(s)
- S Shen
- Department of Pharmacology School of Medicine, East Carolina University, Greenville, NC 27858-4353, USA
| | | |
Collapse
|
6
|
NyklíĈek I, Vmgerhoets ADJ, van Heck GL. The under-reporting tendency of hypertensives: An analysis of potential psychological and physiological mechanisms. Psychol Health 1998. [DOI: 10.1080/08870449808406127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
|
7
|
Boone JB, Corry JM. Proenkephalin gene expression in the brainstem regulates post-exercise hypotension. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1996; 42:31-8. [PMID: 8915577 DOI: 10.1016/s0169-328x(96)00105-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The opioid receptor antagonist naloxone reverses the reduction in blood pressure following exercise. We have previously demonstrated that compared to genetically matched controls, spontaneously hypertensive rats (SHR) have decreased proenkephalin mRNA levels in the nucleus tractus solitarius (NTS), the caudal (CVLM) and rostral ventrolateral medulla (RVLM) of the brainstem. We hypothesized that in SHR an acute bout of exercise would increase proenkephalin mRNA in the NTS and RVLM. Female 12-week-old SHR (n = 4/group) were randomly assigned to exercise and control groups. Mean arterial pressure (MAP) and heart rate were recorded at rest and every 5 min for 30 min following: (1) 40 min of treadmill running at 30 m/min, 10% grade; or (2) 40 min of rest on the treadmill. Rats were sacrificed 30 min post-exercise or post-rest. Exercise induced increases in MAP and heart rate, approximately 18 mmHg and approximately 140 beats/min, respectively, P < 0.001. There were no differences in pre-exercise/rest MAP between groups, or in control rats following rest on the treadmill, 162.5 +/- 3 vs. 163.1 +/- 4 mmHg, control and control after treadmill rest, respectively; NS P > 0.05. The pre- to post-exercise reduction in MAP after 40 min of treadmill running was from 164 +/- 5.1 to 146 +/- 2.0 mmHg (P < 0.001) as recorded 30 min post-exercise. At 30 min post-exercise proenkephalin mRNA levels in the NTS, CVLM and RVLM were increased: 97, 198 and 227%, respectively, P < 0.01. These data reconfirm the existence of post-exercise hypotension in SHR and suggest that increases in enkephalin synthesis and release in the NTS, CVLM, and RVLM may be involved in regulating post-exercise hypotension.
Collapse
Affiliation(s)
- J B Boone
- Department of Psychiatry and Biobehavioral Sciences, UCLA-NPI, Westwood 90024-1759, USA.
| | | |
Collapse
|
8
|
Sun SY, Liu Z, Li P, Ingenito AJ. Central effects of opioid agonists and naloxone on blood pressure and heart rate in normotensive and hypertensive rats. GENERAL PHARMACOLOGY 1996; 27:1187-94. [PMID: 8981066 DOI: 10.1016/s0306-3623(96)00055-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
1. The central cardiovascular effects of several opioid receptor selective agonists and the nonselective opioid antagonist, naloxone, were studied in anesthetized normotensive control rats, in spontaneously hypertensive rats (SHR), and in foot-shock-stressed rats. 2. Receptor-selective agonists injected into the rostral ventrolateral medulla (RVLM), paraventricular nucleus (PVN), and dorsal hippocampus (dHip) were DAGO (mu), DADLE (delta), and U50,488H (kappa). 3. DAGO and DADLE (3 nM) decreased arterial pressure and heart rate in RVLM and PVN of all rat strains, while U-50,488H (9 nM) had only minimal effects in these areas. 4. In dHip, only DADLE (3 nM) had depressor and bradycardic effects, and then, only in SHR, with DAGO and U50,488H being ineffective in any strain, even at 9 nM. 5. Prior injection of naloxone (10 nM) into the RVLM, PVN and dHip blocked and postinjection reversed the cardiovascular effects of the agonists. Naloxone alone increased blood pressure and heart rate in all three areas, in all rat strains except SHR, suggesting a tonic depressor effect of endogenous opioids. 6. Lack of significant quantitative differences in opioid agonist and antagonist effects between normotensive and hypertensive or stressed rats argues against a role for endogenous brain opioids in experimental hypertension.
Collapse
MESH Headings
- Animals
- Blood Pressure/drug effects
- Heart Rate/drug effects
- Hippocampus/physiology
- Hypertension/genetics
- Hypertension/physiopathology
- Medulla Oblongata/physiology
- Microinjections
- Naloxone/pharmacology
- Narcotic Antagonists/pharmacology
- Paraventricular Hypothalamic Nucleus/physiology
- Rats
- Rats, Inbred SHR
- Rats, Inbred WKY
- Rats, Sprague-Dawley
- Receptors, Opioid/agonists
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, mu/agonists
- Stress, Psychological/physiopathology
Collapse
Affiliation(s)
- S Y Sun
- Department of Physiology, Shanghai Medical University, People's Republic of China
| | | | | | | |
Collapse
|
9
|
Zheng X, Zhang T, Ding H, Wang C. Plasma levels of beta-endorphin, leucine enkephalin and arginine vasopressin in patients with essential hypertension and the effects of clonidine. Int J Cardiol 1995; 51:233-44. [PMID: 8586472 DOI: 10.1016/0167-5273(95)02423-t] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In order to investigate the changes of endogenous opiate systems in hypertension and their possible role in the pathogenesis in hypertension, we measured plasma concentrations of beta-endorphin, leucine-enkephalin, neurotension, arginine vasopressin, plasma renin activity and angiotensin II by radioimmunoassay in 60 normal persons and 120 patients with essential hypertension. The results showed that the patient group had lower levels of beta-endorphin and leucine enkephalin (P < 0.001), higher levels of arginine vasopressin, plasma renin activity and angiotensin II (P < 0.01, P < 0.05 and P < 0.05, respectively), and normal level of neurotensin, as compared with those in normal group. Plasma levels of leucine-enkephalin was correlated negatively to the mean artery pressure (r = -0.196, P < 0.05). Plasma level of arginine vasopressin was correlated to the duration of the hypertension (r = 0.216, P < 0.05). After 150 min and 14 days of treatment with clonidine, plasma levels of beta-endorphin, leucine-enkephalin increased significantly (< 0.01) and correlated negatively with the decrease of the mean artery pressure (r = -0.340 and r = -0.436 at 150 min, r = -0.369 and r = -0.441 on the 14th day, respectively, P < 0.01). Plasma renin activity and angiotensin II decreased significantly (P < 0.05 and P < 0.01). Arginine vasopressin and neurotensin did not change significantly. After intravenous administration of opiate antagonist-naloxone, the blood pressure and heart rate increased significantly (P < 0.01). The results suggested that the changes of endogenous opioids may be involved in the pathogenesis of hypertension and in the antihypertensive action of clonidine.
Collapse
Affiliation(s)
- X Zheng
- Department of Cardiology, Changhai Hospital, Shanghai, China
| | | | | | | |
Collapse
|
10
|
Boone JB, McMillen D. Proenkephalin gene expression is altered in the brain of spontaneously hypertensive rats during the development of hypertension. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1994; 24:320-6. [PMID: 7968371 DOI: 10.1016/0169-328x(94)90145-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Enkephalins have been discovered in various regions of the brain involved in cardiovascular regulation. Sympathoadrenal hyperactivity and altered baroreflex activity have been implicated in the development of hypertension. The purpose of this investigation was to determine whether proenkephalin gene expression is altered in the arterial baroreceptor reflex region of the brain and in neurons involved in regulating sympathetic outflow, during the development of hypertension. Proenkephalin mRNA levels were compared, using in situ hybridization, in 4- and 14 week-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). Systolic blood pressure was measured by tail-cuff impedance plethysmography. There were no differences in blood pressure at 4 weeks, however by 14 weeks resting systolic blood pressure was approximately 40% higher in SHR (162.5 +/- 1.6 vs. 117.3 +/- 1.5 mmHg). Proenkephalin gene expression in the nucleus tractus solitarius (NTS), caudal (CVLM) and rostral ventrolateral medulla (RVLM) was lower (approximately 67, 50, and 55%, respectively) in the SHR at 14 weeks. However, in the locus coeruleus (LC), anterior (AH) and lateral hypothalamus (LH), proenkephalin mRNA was significantly increased (approximately 50, 100 and 100%, respectively) in the SHR. The decrease in proenkephalin mRNA in the NTS, CVLM, and RVLM may attenuate arterial baroreceptor reflex activity, while the increase in proenkephalin mRNA in the LC, AH and LH may increase sympathetic tone by inhibiting the activity of sympathodepressor preganglionic neurons in the intermediolateral cell column of the spinal cord.
Collapse
Affiliation(s)
- J B Boone
- University of Missouri, Department of Veterinary Biomedical Sciences, Columbia 65211
| | | |
Collapse
|
11
|
Wong SC, Ingenito AJ. Possible opioid receptor function changes in isolated atria of the spontaneously hypertensive rat. GENERAL PHARMACOLOGY 1993; 24:1483-90. [PMID: 8112524 DOI: 10.1016/0306-3623(93)90440-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
1. A comparison of the effects of various opioid peptides on the heart rates of self-paced right atria was made, as taken from spontaneously hypertensive (SHR), Wistar Kyoto (WKY) and Sprague-Dawley (SD) rats at 4, 8, 12 and 16 weeks of age. 2. Beta-endorphin, dynorphin, met-enkephalin, DAGO and DADLE slightly decreased the spontaneously beating rate of all rat strains and ages, at 0.1 microM. Leu-enkephalin at 0.2 microM increased the spontaneous beating rate of SHR atria, but not that of atria from normotensive strains. 3. SHR atria were somewhat more sensitive than WKY atria to norepinephrine (NE)-induced positive chronotropy, but the differences were not statistically significant. 4. In the presence of mu, delta or kappa opioid receptor agonists, SHR atrial sensitivity to NE-induced chronotropy was enhanced at all ages studied. By contrast, NE chronotropy was not significantly altered by the opioids in normotensive rat atria. 5. Based on the above results, all the three major opioid receptor subtypes (mu, delta and kappa) appear to be present in rat atria but the function of these receptors appears to be greater in SHR than in WKY and SD atria. 6. The results suggest a possible involvement of altered opioid responsiveness in atria during hypertension development in SHR but the nature of this involvement appears to be complex and is not readily understandable on the basis of the present study.
Collapse
Affiliation(s)
- S C Wong
- Department of Pharmacology, School of Medicine, East Carolina University, Greenville, NC 27858
| | | |
Collapse
|
12
|
Ditto B, Edwards MC, Miller S, D'Antono B, Blum S. The effects of sodium loading on blood pressure and pain responses to the cold pressor test. J Psychosom Res 1993; 37:771-80. [PMID: 8229908 DOI: 10.1016/0022-3999(93)90106-p] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Two cold pressor tests were administered to 18 healthy normotensive males on two occasions, after 2 weeks of dietary sodium loading and after 2 weeks of maintaining their normal diet. While the addition of an extra 10 g/day of sodium to the diet had no overall effect on resting cardiovascular activity, it produced significantly greater diastolic blood pressure and smaller heart rate responses to the pain stimuli. As well, consistent with the large animal literature indicating a relationship between high blood pressure and diminished pain sensitivity, pain ratings were found to be significantly lower during the sodium loaded testing session. The ratings were corroborated by evidence of lower skin conductance reactivity to the second cold pressor test in the sodium loaded condition. Information concerning an elevation of risk for hypertension, perhaps provided by baroreceptors, may lead to compensatory reactions with hypoalgesia as one effect.
Collapse
Affiliation(s)
- B Ditto
- Department of Psychology, McGill University, Montreal, Quebec, Canada
| | | | | | | | | |
Collapse
|
13
|
Widy-Tyszkiewicz E, Scheel-Krüger J, Christensen AV. Enhanced disruptive spatial learning effect after sufentanil in renal hypertensive rats versus normotensive rats. Physiol Behav 1993; 53:467-75. [PMID: 8451311 DOI: 10.1016/0031-9384(93)90140-b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effects of the peripherally administered sufentanil citrate (S), a potent opioid agonist with high affinity for mu receptors on the spatial navigation task, were tested in normotensive Wistar (NR) and renal hypertensive rats (RHR). Rats were injected subcutaneously once daily in doses of 0.25 or 1 microgram/kg S before the water maze training. In NR rats, weak effects of 0.25 micrograms/kg S and impairments after 1 microgram/kg S were seen, whereas in RHR 0.25 and 1 microgram/kg S showed clearcut impairments. These data from the Morris water maze task support previous reports that RHR have an increased sensitivity for opioid agonists.
Collapse
Affiliation(s)
- E Widy-Tyszkiewicz
- Department of Experimental and Clinical Pharmacology, Medical Academy, Warszawa, Poland
| | | | | |
Collapse
|
14
|
Szilagyi JE. Psychosocial stress elevates blood pressure via an opioid dependent mechanism in normotensive rats. CLINICAL AND EXPERIMENTAL HYPERTENSION. PART A, THEORY AND PRACTICE 1991; 13:1383-94. [PMID: 1760893 DOI: 10.3109/10641969109048800] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Stress is an important risk factor in cardiovascular diseases, including hypertension. Endogenous opioids are known to be elevated in stress and in various models of hypertension with differing etiologies. Blockade of endogenous opioids with naloxone has been demonstrated to attenuate or reverse the elevation in blood pressure in both renovascular and spontaneous hypertension. In the current study, increased blood pressure was induced using a model of psychosocial stress. During the first week of stress, systolic blood pressure rose rapidly to reach a level that was sustained throughout the remaining period of stress. Chronic infusion of the opiate antagonist, naloxone, both prevented and completely reversed the elevated blood pressure due to psychosocial stress. These data demonstrate that elevated endogenous opioids are important factors in cardiovascular regulation and are likely to influence both the development and maintenance of stress-induced hypertension.
Collapse
Affiliation(s)
- J E Szilagyi
- Department of Pharmacology, University of Houston, Texas 77204-5515
| |
Collapse
|
15
|
Abstract
This paper is the twelfth installment of our annual review of the research published during 1989 involving the behavioral, nonanalgesic, effects of the endogenous opiate peptides. The specific topics this year include stress; tolerance and dependence; eating; drinking; gastrointestinal and renal functions; mental illness; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; locomotor activity; sex, development, pregnancy, and aging; immunological responses; and other behavior.
Collapse
Affiliation(s)
- G A Olson
- Department of Psychology, University of New Orleans, LA 70148
| | | | | |
Collapse
|