We have developed a method to evaluate the hypertensive response after noxious stimuli in anesthetized rats. Anesthetic level, stimuli, and responses were standardized by using an etomidate infusion, a series of stimuli of increasing intensity applied to the tail, and measuring maximal changes in systolic blood pressure (delta SBP) after each stimulus. Normotensive Sprague Dawley rats (SD) (n = 7) were studied using an etomidate infusion of 4.2 mg.kg-1 x h-1. This method was then applied to spontaneously hypertensive rats (SHR) anesthetized with three rats of etomidate infusion: Group 1 (n = 8), 7.0 mg.kg-1 x h-1; Group 2 (n = 8), 5.6 mg.kg-1 x h-1; and Group 3 (n = 11), 4.2 mg.kg-1 x h-1. Under anesthesia, three types of noxious stimuli were applied to the tail at 1-min intervals (13 total): (a) Type 1:11 2-s electrical stimuli of increasing intensity (0.4-12 mA, to produce threshold to maximal responses); (b) Type 2: one intense, prolonged electrical stimulus (10 mA, 5 s); and (c) Type 3: tail-clamping. After each stimulus, delta SBP was measured. In the SHR, comparing single delta SBP responses to single noxious stimuli after each of the three most intense stimuli showed no statistically significant differences among the three anesthetic groups. In contrast, comparison of dose-response curves of multiple delta SBP responses to multiple Type 1 (2-s) stimuli demonstrated a significant difference among the three anesthetic groups of SHR.(ABSTRACT TRUNCATED AT 250 WORDS)
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Neuroscience
January 2025
Center for Neuroscience, Indian Institute of Science, Bengaluru 560012, India. Electronic address:
Pain and itch are unpleasant and distinct sensations that give rise to behaviors such as reflexive withdrawal and scratching in humans and mice. Interestingly, it has been observed that pain modulate itch through the neural circuits housed in the brain and spinal cord. However, we are yet to fully understand the identities of, and mechanisms by which specific neural circuits mediate pain-induced modulation of itch.
View Article and Find Full Text PDFPharmaceutics
December 2024
Department of Pharmaceutical Sciences, School of Pharmacy and Nutrition, University of Navarra, 31008 Pamplona, Spain.
: Despite the known impact of propofol and remifentanil on hemodynamics and patient outcomes, there is a lack of comprehensive quantitative analysis, particularly in surgical settings, considering the influence of noxious stimuli. The aim of this study was to develop a quantitative semi-mechanistic population model that characterized the time course changes in mean arterial pressure (MAP) and heart rate (HR) due to the effects of propofol, remifentanil, and different types of noxious stimulation related to the clinical routine. : Data from a prospective study were used; the study analyzed the effects of propofol and remifentanil general anesthesia on female patients in physical status of I-II according to the American Society of Anesthesiologists (ASA I-II) undergoing gynecology surgery.
View Article and Find Full Text PDFLife (Basel)
December 2024
College of Chinese Medicine, Graduate Institute of Acupuncture Science, China Medical University, Taichung 40402, Taiwan.
Background: Fibromyalgia (FM) is characterized by chronic pain, significantly affecting the quality of life and functional capabilities of patients. In addition to pain, patients may experience insomnia, chronic fatigue, depression, anxiety, and headaches, further complicating their overall well-being. The Transient Receptor Potential Vanilloid 1 (TRPV1) receptor responds to various noxious stimuli and plays a key role in regulating pain sensitivity and inflammation.
View Article and Find Full Text PDFCurr Biol
December 2024
Department of Biology, Indiana University, Bloomington, IN 47405, USA; Gill Institute for Neuroscience, Indiana University, Bloomington, IN 47405, USA; Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA. Electronic address:
Evolutionary arms races can lead to extremely specific and effective defense mechanisms, including venoms that deter predators by targeting nociceptive (pain-sensing) pathways. The venom of velvet ants (Hymenoptera: Mutillidae) is notoriously painful. It has been described as "Explosive and long lasting, you sound insane as you scream.
View Article and Find Full Text PDFNat Neurosci
January 2025
Department of Physiology, Seoul National University College of Medicine, Seoul, Korea.
The cerebellum is activated by noxious stimuli and pathological pain but its role in noxious information processing remains unknown. Here, we show that in mice, cutaneous noxious electrical stimuli induced noradrenaline (NA) release from locus coeruleus (LC) terminals in the cerebellar cortex. Bergmann glia (BG) accumulated these LC-NA signals by increasing intracellular calcium in an integrative manner ('flares').
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