1
|
Kapsdorferová V, Grešová S, Švorc P. Measurement of blood pressure in rats: Invasive or noninvasive methods? Physiol Rep 2024; 12:e70041. [PMID: 39266877 PMCID: PMC11392657 DOI: 10.14814/phy2.70041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2024] [Revised: 08/22/2024] [Accepted: 08/29/2024] [Indexed: 09/14/2024] Open
Abstract
Experiments should always be based on control values. This assumption fully applies to cardiovascular parameters, such as heart rate (HR) and blood pressure (BP), which are highly sensitive to various external and internal stimuli and can already be significantly altered when an experiment begins. Therefore, it is necessary to determine which values are defined as a starting point (i.e., control and baseline) or compare them with valid reference values if the goal is to evaluate the changes after experimental intervention. A generally accepted principle is a reciprocal relationship between BP and HR, in which one parameter affects the other and vice versa. BP can be measured using two methods-noninvasively (tail-cuff) and invasively (telemetry, direct measurements of BP after introducing the sensor directly into the artery), and HR directly or by extrapolation from BP recordings. This study does not aim to evaluate the results of individual studies, but to review whether there are differences in control (baseline) BP values in normotensive and hypertensive male rats using invasive versus noninvasive methods, and to investigate whether there is a causal relationship between BP and HR in in vivo experiments with male rats.
Collapse
Affiliation(s)
- Viktória Kapsdorferová
- Department of Medical Physiology, Faculty of MedicinePavol Jozef Safarik UniversityKosiceSlovakia
| | - Soňa Grešová
- Department of Medical Physiology, Faculty of MedicinePavol Jozef Safarik UniversityKosiceSlovakia
| | - Pavol Švorc
- Department of Medical Physiology, Faculty of MedicinePavol Jozef Safarik UniversityKosiceSlovakia
| |
Collapse
|
2
|
Grau JW, Hudson KE, Johnston DT, Partipilo SR. Updating perspectives on spinal cord function: motor coordination, timing, relational processing, and memory below the brain. Front Syst Neurosci 2024; 18:1184597. [PMID: 38444825 PMCID: PMC10912355 DOI: 10.3389/fnsys.2024.1184597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 01/29/2024] [Indexed: 03/07/2024] Open
Abstract
Those studying neural systems within the brain have historically assumed that lower-level processes in the spinal cord act in a mechanical manner, to relay afferent signals and execute motor commands. From this view, abstracting temporal and environmental relations is the province of the brain. Here we review work conducted over the last 50 years that challenges this perspective, demonstrating that mechanisms within the spinal cord can organize coordinated behavior (stepping), induce a lasting change in how pain (nociceptive) signals are processed, abstract stimulus-stimulus (Pavlovian) and response-outcome (instrumental) relations, and infer whether stimuli occur in a random or regular manner. The mechanisms that underlie these processes depend upon signal pathways (e.g., NMDA receptor mediated plasticity) analogous to those implicated in brain-dependent learning and memory. New data show that spinal cord injury (SCI) can enable plasticity within the spinal cord by reducing the inhibitory effect of GABA. It is suggested that the signals relayed to the brain may contain information about environmental relations and that spinal cord systems can coordinate action in response to descending signals from the brain. We further suggest that the study of stimulus processing, learning, memory, and cognitive-like processing in the spinal cord can inform our views of brain function, providing an attractive model system. Most importantly, the work has revealed new avenues of treatment for those that have suffered a SCI.
Collapse
Affiliation(s)
- James W. Grau
- Lab of Dr. James Grau, Department of Psychological and Brain Sciences, Cellular and Behavioral Neuroscience, Texas A&M University, College Station, TX, United States
| | | | | | | |
Collapse
|
3
|
Fauss GNK, Hudson KE, Grau JW. Role of Descending Serotonergic Fibers in the Development of Pathophysiology after Spinal Cord Injury (SCI): Contribution to Chronic Pain, Spasticity, and Autonomic Dysreflexia. BIOLOGY 2022; 11:234. [PMID: 35205100 PMCID: PMC8869318 DOI: 10.3390/biology11020234] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/27/2022] [Accepted: 01/29/2022] [Indexed: 12/12/2022]
Abstract
As the nervous system develops, nerve fibers from the brain form descending tracts that regulate the execution of motor behavior within the spinal cord, incoming sensory signals, and capacity to change (plasticity). How these fibers affect function depends upon the transmitter released, the receptor system engaged, and the pattern of neural innervation. The current review focuses upon the neurotransmitter serotonin (5-HT) and its capacity to dampen (inhibit) neural excitation. A brief review of key anatomical details, receptor types, and pharmacology is provided. The paper then considers how damage to descending serotonergic fibers contributes to pathophysiology after spinal cord injury (SCI). The loss of serotonergic fibers removes an inhibitory brake that enables plasticity and neural excitation. In this state, noxious stimulation can induce a form of over-excitation that sensitizes pain (nociceptive) circuits, a modification that can contribute to the development of chronic pain. Over time, the loss of serotonergic fibers allows prolonged motor drive (spasticity) to develop and removes a regulatory brake on autonomic function, which enables bouts of unregulated sympathetic activity (autonomic dysreflexia). Recent research has shown that the loss of descending serotonergic activity is accompanied by a shift in how the neurotransmitter GABA affects neural activity, reducing its inhibitory effect. Treatments that target the loss of inhibition could have therapeutic benefit.
Collapse
Affiliation(s)
| | | | - James W. Grau
- Department of Psychological and Brain Sciences, Texas A&M University, College Station, TX 77843, USA; (G.N.K.F.); (K.E.H.)
| |
Collapse
|
4
|
Baine RE, Johnston DT, Strain MM, Henwood MK, Davis JA, Reynolds JA, Giles ED, Grau JW. Noxious Stimulation Induces Acute Hemorrhage and Impairs Long-Term Recovery after Spinal Cord Injury (SCI) in Female Rats: Evidence Estrous Cycle May Have a Modulatory Effect. Neurotrauma Rep 2022; 3:70-86. [PMID: 35112109 PMCID: PMC8804264 DOI: 10.1089/neur.2021.0055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Spinal cord injuries (SCIs) are often the result of traumatic accidents, which also produce multiple other injuries (polytrauma). Nociceptive input from associated injuries has been shown to significantly impair recovery post-SCI. Historically, work in our laboratory has focused exclusively on male animals; however, increasing incidence of SCI in females requires research to determine whether pain (nociceptive) input poses the same risk to their recovery. Some animal studies have shown that females demonstrate greater tissue preservation and better locomotor recovery post-SCI. Given this, we examined the effect of sex on SCI recovery in two pain models—intermittent electrical stimulation (shock) to the tail or capsaicin injection to the hindpaw. Female rats received a lower thoracic contusion injury and were exposed to noxious stimulation the next day. The acute effect of noxious input on cardiovascular function, locomotor performance, and hemorrhage were assessed. Treatment with capsaicin or noxious electrical stimulation disrupted locomotor performance, increased blood pressure, and disrupted stepping. Additional experiments examined the long-term consequences of noxious input, demonstrating that both noxious electrical stimulation and capsaicin impair long-term recovery in female rats. Interestingly, injury had a greater effect on behavioral performance when progesterone and estrogen were low (metestrus). Conversely, nociceptive input led to a greater disruption in locomotor performance and produced a greater rise in blood pressure in animals injured during estrus.
Collapse
Affiliation(s)
- Rachel E. Baine
- Department of Psychological and Brain Sciences, Texas A&M University, College Station, Texas, USA
| | - David T. Johnston
- Department of Psychological and Brain Sciences, Texas A&M University, College Station, Texas, USA
| | - Misty M. Strain
- Department of Cellular and Integrative Physiology, University of Texas Health Science, San Antonio, Texas, USA
| | - Melissa K. Henwood
- Department of Neuroscience, Cell Biology, Anatomy, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jacob A. Davis
- Department of Psychological and Brain Sciences, Texas A&M University, College Station, Texas, USA
| | - Joshua A. Reynolds
- Department of Psychological and Brain Sciences, Texas A&M University, College Station, Texas, USA
| | - Erin D. Giles
- Department of Nutrition, Texas A&M University, College Station, Texas, USA
| | - James W. Grau
- Department of Psychological and Brain Sciences, Texas A&M University, College Station, Texas, USA
| |
Collapse
|