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Lamont KA, Boynton MH, Hickman DL, Fletcher CA, Williams MD. Acute Effects of Hypothermia and Inhalant Anesthesia on Ultrasonic Vocalizations and Neuroendocrine Markers in Neonatal Rats. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2024; 63:57-66. [PMID: 38040412 PMCID: PMC10844739 DOI: 10.30802/aalas-jaalas-23-000008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 02/28/2023] [Accepted: 10/23/2023] [Indexed: 12/03/2023]
Abstract
Neonatal rodents undergo anesthesia for numerous procedures and for euthanasia by anesthetic overdose. However, data regarding whether neonatal anesthesia is humane are limited. Hypothermia (cryoanesthesia) is the most commonly used anesthetic protocol for neonatal rats 10 d of age or younger. However, hypothermia has recently been restricted in several countries due to perceived painful effects, including pain on rewarming. Minimizing the potential pain and distress of neonates in research is imperative, although very challenging. Traditional validated and nonvalidated behavioral and physiologic outcome measures used for adult rats undergoing anesthesia are unsuitable for evaluating neonates. Therefore, we investigated the effects of several anesthetic methods on neonatal rats by using the innovative objective approaches of noninvasive ultrasonic vocalizations and more invasive neuroendocrine responses (i. e., serum corticosterone, norepinephrine, glucose). Our results show that hypothermia leads to heightened acute distress in neonatal rats as indicated by prolonged recovery times, increased duration of vocalizations, and elevated corticosterone levels, as compared with neonates undergoing inhalational anesthesia. We demonstrate that inhalational anesthesia is preferable to cryoanesthesia for neonatal rats, and researchers using hypothermia anesthesia should consider using inhalational anesthesia as an alternative method.
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Affiliation(s)
| | - Marcella H Boynton
- Division of General Medicine and Clinical Epidemiology, School of Medicine, and
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Debra L Hickman
- Laboratory Animal Resource Center, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana; and
| | - Craig A Fletcher
- Division of Comparative Medicine
- Department of Pathology and Laboratory Medicine
| | - Morika D Williams
- Division of Comparative Medicine
- Department of Pathology and Laboratory Medicine
- Thurston Arthritis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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McKenna BA, Weaver HL, Kim J, Bowman MW, Knych HK, Kendall LV. A Pharmacokinetic and Analgesic Efficacy Study of Carprofen in Female CD1 Mice. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2023; 62:545-552. [PMID: 37758465 PMCID: PMC10772918 DOI: 10.30802/aalas-jaalas-23-000041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 06/06/2023] [Accepted: 06/23/2023] [Indexed: 09/29/2023]
Abstract
The minimization of pain in research animals is a scientific and ethical necessity. Carprofen is commonly used for pain management in mice; however, some data suggest that the standard dosage of 5 mg/kg may not provide adequate analgesia after surgery. We hypothesized that a higher dose of carprofen in mice would reduce pain-associated behaviors and improve analgesia without toxic effects. A pharmacokinetic study was performed in mice given carprofen subcutaneously at 10 or 20 mg/kg. Plasma concentrations were measured at 0.25, 0.5, 1, 2, 4, 8, 12, 24, and 48 h after dosing (n = 3 per time point and treatment). At these doses, plasma levels were above the purported therapeutic level for at least 12 and 24 h, respectively, with respective half-lives of 14.9 and 10.2 h. For the efficacy study, 10 mice per group received anesthesia with or without an ovariectomy. Mice were then given 5 or 10 mg/kg of carprofen, or saline subcutaneously every 12 h. Orbital tightening, arched posture, wound licking, rearing, grooming, nesting behavior, and activity were assessed before surgery and at 4, 8, 12, 24, and 48 h after surgery. The von Frey responses were assessed before and at 4, 12, 24, and 48 h after surgery. The efficacy study showed that all surgery groups had significantly higher scores for orbital tightening, arched posture, and wound licking than did the anesthesia-only groups at 4, 8, 12, and 24-h time points. At the 8 h time point, the surgery groups treated with carprofen had significantly lower arched posture scores than did the surgery group treated with saline only. No significant differences were found between carprofen treatment groups for rearing, grooming, von Frey, activity, or nesting behavior at any time point. These results indicate that subcutaneous carprofen administered at these doses does not provide sufficient analgesia to alleviate postoperative pain in female CD1 mice.
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Affiliation(s)
- Brandon A McKenna
- Laboratory Animal Resources, Colorado State University, Fort Collins, Colorado
| | - Hannah L Weaver
- Laboratory Animal Resources, Colorado State University, Fort Collins, Colorado
| | - Jeffrey Kim
- Comparative Medicine Research Unit, School of Medicine, University of Louisville, Louisville, Kentucky
| | - Madelyn W Bowman
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Heather K Knych
- K.L. Maddy Equine Analytical Pharmacology Laboratory, School of Veterinary Medicine, University of California, Davis, California; and
- Department of Veterinary Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California
| | - Lon V Kendall
- Laboratory Animal Resources, Colorado State University, Fort Collins, Colorado
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado
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Kim J, Cannon BA, Freeman LE, Tan S, Knych HK, Kendall LV. High-dose Meloxicam Provides Improved Analgesia in Female CD1 Mice: A Pharmacokinetic and Efficacy Study. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2023; 62:74-80. [PMID: 36755203 PMCID: PMC9936853 DOI: 10.30802/aalas-jaalas-22-000064] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Meloxicam is a nonsteroidal anti-inflammatory analgesic drug that is often used in mice. However, doses of 1 to 5 mg/kg given twice daily were recently reported to provide inadequate analgesia. Some studies suggest that doses of up to 20 mg/kg may be necessary for adequate pain management. We investigated the analgesia provided by a high-dose of meloxicam in female CD1 mice. Pharmacokinetic analyses demonstrated that a subcutaneous injection of 10 mg/kg or 20 mg/kg of meloxicam produced therapeutic plasma concentrations for at least 12 h. Ovariectomies via ventral laparotomy were performed to assess analgesic efficacy. Mice were treated immediately before surgery with a high-dose of 10 mg/kg, a low-dose of 2.5 mg/kg, or saline, followed by every 12 h for 36 h. At 3, 6, 12, 24, and 48 h after surgery, mice were assessed for pain based on the following behaviors: distance traveled, time mobile, grooming, rearing, hunched posture, orbital tightening, and von Frey. Initially, some mice received a 20-mg/kg loading dose followed by 10 mg/kg every 12 h. This regimen caused severe morbidity and mortality in 2 mice. Subsequently, this regimen was abandoned, and mice assigned to the high-dose group received 10 mg/kg every 12 h. Mice that received the 10-mg/kg dose after surgery showed less orbital tightening between 3 to 6 h and reduced frequency of hunched posture for 48 h compared with mice that received either the low-dose or saline. However, mice were significantly less mobile for 6 to 12 h after surgery regardless of treatment. These data indicate that a meloxicam dose of 10 mg/kg every 12 h provides better analgesia than a 2.5-mg/kg dose but does not completely alleviate pain.
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Affiliation(s)
- Jeffrey Kim
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences,,Laboratory Animal Resources, Colorado State University, Fort Collins, Colorado,,Corresponding author.
| | - Brinley A Cannon
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences,,Laboratory Animal Resources, Colorado State University, Fort Collins, Colorado
| | - Layne E Freeman
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences,,Laboratory Animal Resources, Colorado State University, Fort Collins, Colorado
| | - Sarah Tan
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences,,Laboratory Animal Resources, Colorado State University, Fort Collins, Colorado
| | - Heather K Knych
- Department of Veterinary Molecular Biosciences and K.L. Maddy Analytical Pharmacology Laboratory, School of Veterinary Medicine, University of California, Davis, California
| | - Lon V Kendall
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences,,Laboratory Animal Resources, Colorado State University, Fort Collins, Colorado
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Marques Miranda C, de Lima Campos M, Leite-Almeida H. Diet, body weight and pain susceptibility - A systematic review of preclinical studies. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2021; 10:100066. [PMID: 34195483 PMCID: PMC8237587 DOI: 10.1016/j.ynpai.2021.100066] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/26/2021] [Accepted: 06/11/2021] [Indexed: 02/07/2023]
Abstract
Obesity has been associated with increased chronic pain susceptibility but causes are unclear. In this review, we systematize and analyze pain outcomes in rodent models of obesity as these can be important tools for mechanistic studies. Studies were identified using MEDLINE/PubMed and Scopus databases using the following search query: (((pain) OR (nociception)) AND (obesity)) AND (rat OR (mouse) OR (rodent))). From each eligible record we extracted the following data: species, strain, sex, pain/obesity model and main behavioral readouts. Out of 695 records 33 were selected for inclusion. 27 studies assessed nociception/acute pain and 17 studies assessed subacute or chronic pain. Overall genetic and dietary models overlapped in pain-related outcomes. Most acute pain studies reported either decreased or unaltered responses to noxious painful stimuli. However, decreased thresholds to mechanical innocuous stimuli, i.e. allodynia, were frequently reported. In most studies using subacute and chronic pain models, namely of subcutaneous inflammation, arthritis and perineural inflammation, decreased thresholds and/or prolonged pain manifestations were reported in obesity models. Strain comparisons and longitudinal observations indicate that genetic factors and the time course of the pathology might account for some of the discrepancies observed across studies. Two studies reported increased pain in animals subjected to high fat diet in the absence of weight gain. Pain-related outcomes in experimental models and clinical obesity are aligned indicating that the rodent can be an useful tool to study the interplay between diet, obesity and pain. In both cases weight gain might represent only a minor contribution to abnormal pain manifestation.
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Affiliation(s)
- Carolina Marques Miranda
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Mariana de Lima Campos
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Hugo Leite-Almeida
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
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