Intraperitoneal injection of sodium pentobarbital is associated with pain in rats

AbstractAn effective and pain-free killing method is required to achieve the goal of euthanasia, a “good death”. Overdose of sodium pentobarbital (PB) by intraperitoneal (IP) injection is a widely accepted technique, but questions remain regarding pain associated with administration. As PB rapidly causes sedation and loss of consciousness, most studies have relied on indirect evidence of pain. The objective of this study was to assess pain associated with IP PB using an appropriate vehicle control.Adult male and female Sprague Dawley (SD) and female Wistar rats (N = 112) were block randomised by sex and strain to receive one of four treatments: 1) 800 mg/kg PB (pH 11); 2) 800 mg/kg PB with 4 mg/kg lidocaine (PB+lido); 3) saline or 4) vehicle controls (pH 11 or 12.5). Behavior (Rat Grimace Scale [RGS], writhing, back arching) was evaluated at baseline, before loss of righting reflex (PB and PB+lido groups), 80s, 151s and 10 min post-injection (PI; saline and vehicle control groups).In the vehicle control groups, the RGS scores were increased at 151s PI (SD: p = 0.0008, 95%CI −0.731 to −0.202) from baseline, as was relative frequency of writhing (SD: p < 0.00001; Wistar; p = 0.0004). RGS scores remained elevated 10 mins PI (SD: p = 0.0070, 95%CI −0.768 to −0.118; Wistar: p = 0.0236, 95%CI −0.907 to −0.0742) but the relative frequency of writhing did not (p > 0.05). The RGS scores and the relative frequency of writhing remained low in the PB, PB+lido and saline groups (p > 0.05). Back arching increased from baseline in the PB+lido group before loss of righting reflex and in the vehicle control group (SD rats) at 151s PI (p < 0.05).These results show that IP PB results in signs associated with pain. The sedative effects of PB limit behavioral assessment.

Download Full-text

Refinement of intraperitoneal injection of sodium pentobarbital for euthanasia in laboratory rats (Rattus norvegicus)

10.1101/081414 ◽

2016 ◽

Author(s):

K Zatroch ◽

CG Knight ◽

JN Reimer ◽

DSJ Pang

Keyword(s):

Coefficient Of Variation ◽

Low Dose ◽

High Volume ◽

High Dose ◽

Sodium Pentobarbital ◽

Sprague Dawley ◽

Loss Of Righting Reflex ◽

Canadian Council ◽

Righting Reflex ◽

Low Volume

AbstractBackgroundThe Canadian Council on Animal Care and American Veterinary Medical Association classify intraperitoneal (IP) pentobarbital as an acceptable euthanasia method in rats. However, federal guidelines do not exist for a recommended dose or volume and IP euthanasia has been described as unreliable, with misinjections leading to variable success in ensuring a timely death. The aims of this study were to assess and improve efficacy and consistency of IP euthanasia.MethodsIn a randomized, blinded study, 51 adult female Sprague-Dawley rats (170-495 g) received one of four treatments: low-dose low-volume (LL) IP pentobarbital (n = 13, 200 mg/kg pentobarbital), low-dose high-volume (LH) IP pentobarbital (n = 14, 200 mg/kg diluted 1:3 with phosphate buffered saline), high-dose high-volume (HH, n = 14, 800 mg/kg pentobarbital), or saline. Times to loss of righting reflex (LORR) and cessation of heartbeat (CHB) were recorded. To identify misinjections, necropsy examinations were performed on all rats. Video recordings of LL and HH groups were analyzed for pain-associated behaviors. Between-group comparisons were performed with 1-way ANOVA and Games-Howell post hoc tests. Variability for CHB was assessed by coefficient of variation (CV) calculation.ResultsThe fastest euthanasia method (CHB) was HH (283.7 ± 38 s), compared with LL (485.8 ± 140.7 s, p = 0.002) and LH (347.7 ± 72.0 s, p = 0.039). Values for CV were: HH, 13.4%; LH, 20.7%; LL, 29.0%. LORR time was longest in LL (139.5 ± 29.6 s), compared with HH (111.6 ± 19.7 s, p = 0.046) and LH (104.2 ± 19.3 s, p = 0.01). Misinjections occurred in 15.7% (8/51) of euthanasia attempts. Pain-associated behavior incidence ranged from 36% (LL) to 46% (HH).ConclusionThese data illustrate refinement of this euthanasia technique. Both dose and volume contribute to speed of death with IP pentobarbital and an increase in volume alone does not significantly reduce variability. The proportion of misinjections was similar to that of previous studies.AbbreviationsLLlow-dose low-volumeLHlow-dose high-volumeHHhigh-dose high-volumeLORRloss of righting reflexCHBcessation of heartbeatGITgastrointestinal tractCVcoefficient of variation

Download Full-text

Carcinogenicity Evaluation: Comparison of Tumor Data from Dual Control Groups in the Sprague–Dawley Rat

Toxicologic Pathology ◽

10.1080/019262390908371 ◽

2005 ◽

Vol 33 (2) ◽

pp. 283-291 ◽

Cited By ~ 33

Author(s):

Paul Baldrick

Keyword(s):

Vital Role ◽

Control Group ◽

Dual Control ◽

Sprague Dawley ◽

Control Groups ◽

Background Data ◽

Rat Strain ◽

Continued Use ◽

Risk Potential ◽

Rodent Carcinogenicity

Following recent clarification in Europe that a single control group is now acceptable for rodent carcinogenicity studies, the use of dual controls may be reduced or disappear. To date, virtually nothing has been published on whether this latter situation has improved the identification of tumorigenic risk potential in these studies. In this paper, the results of 13 rat carcinogenicity studies, performed between 1991 and 2002, with 2 control groups, are presented. Although no major differences in tumor incidences between these dual control groups were found, some interstudy variation occurred. In cases where a notable difference was seen, the use of 2 control groups, as well as robust, contemporary background data, allowed an easier interpretation of findings in drug-treated groups. Thus, the continued use of dual control groups has a vital role in the assessment of tumoriogenic risk. The paper also presents an update on survival, on the range and extent of background spontaneous neoplasms, and comments on genetic drift in this commonly used rat strain.

Download Full-text

Inactivation of Prefrontal Cortex Delays Emergence From Sevoflurane Anesthesia

Frontiers in Systems Neuroscience ◽

10.3389/fnsys.2021.690717 ◽

2021 ◽

Vol 15 ◽

Author(s):

Emma R. Huels ◽

Trent Groenhout ◽

Christopher W. Fields ◽

Tiecheng Liu ◽

George A. Mashour ◽

...

Keyword(s):

Prefrontal Cortex ◽

Brain Regions ◽

Association Cortex ◽

Sprague Dawley ◽

Subcortical Structures ◽

Behavioral Arousal ◽

Barrel Field ◽

Loss Of Righting Reflex ◽

Parietal Association Cortex ◽

Righting Reflex

Studies aimed at investigating brain regions involved in arousal state control have been traditionally limited to subcortical structures. In the current study, we tested the hypothesis that inactivation of prefrontal cortex, but not two subregions within parietal cortex—somatosensory barrel field and medial/lateral parietal association cortex—would suppress arousal, as measured by an increase in anesthetic sensitivity. Male and female Sprague Dawley rats were surgically prepared for recording electroencephalogram and bilateral infusion into prefrontal cortex (N = 13), somatosensory barrel field (N = 10), or medial/lateral parietal association cortex (N = 9). After at least 10 days of post-surgical recovery, 156 μM tetrodotoxin or saline was microinjected into one of the cortical sites. Ninety minutes after injection, rats were anesthetized with 2.5% sevoflurane and the time to loss of righting reflex, a surrogate for loss of consciousness, was measured. Sevoflurane was stopped after 45 min and the time to return of righting reflex, a surrogate for return of consciousness, was measured. Tetrodotoxin-mediated inactivation of all three cortical sites decreased (p < 0.05) the time to loss of righting reflex. By contrast, only inactivation of prefrontal cortex, but not somatosensory barrel field or medial/lateral parietal association cortex, increased (p < 0.001) the time to return of righting reflex. Burst suppression ratio was not altered following inactivation of any of the cortical sites, suggesting that there was no global effect due to pharmacologic lesion. These findings demonstrate that prefrontal cortex plays a causal role in emergence from anesthesia and behavioral arousal.

Download Full-text

Evaluation of clinical, histology, TNF-α, and collagen expressions on oral ulcer in rats after treatment with areca nut and chrysanthemum oral gel

F1000Research ◽

10.12688/f1000research.54887.1 ◽

2021 ◽

Vol 10 ◽

pp. 623

Author(s):

Liza Meutia Sari ◽

Zaki Mubarak ◽

Dina Keumala Sari

Keyword(s):

Triamcinolone Acetonide ◽

Positive Control ◽

Flowering Plant ◽

Positive Control Group ◽

Control Group ◽

Areca Nut ◽

Sprague Dawley ◽

Control Groups ◽

Sprague Dawley Rats ◽

Tnf Α

Background: Areca nut (Areca catechu Linn.) is the seed of the fruit of the oriental palm that is commonly used among Southeast Asian communities. Chrysanthemum (Dendrathema grandiflora) is a flowering plant originating from East Asia and dominantly grows in China. Both of these plants have strong antioxidant activities. To investigate the mechanism of their wound healing activities, we prepared areca nut and chrysanthemum polyethylene oral gel and performed several in vivo assays using Sprague–Dawley rats. Methods: Sprague–Dawley rats were divided into five groups: Negative control group (rats with base gel treatment), positive control group (rats treated with triamcinolone acetonide), F1 (treatment with 20% areca nut:80% chrysanthemum), F2 (treatment with 50% areca nut:50% chrysanthemum), and F3 (treatment with 80% areca nut:20% chrysanthemum). Traumatic ulcers were performed on the buccal mucosa of all experimental animals that received topical oral gel and triamcinolone acetonide twice a day for seven days. The clinical and histological characteristics were analyzed and scored. Results: During the six days, the ulcerated area receded linearly over time and was completely cicatrized in F2 and positive control group (Dependent t-test, p<0.05). There were significant increases in body weight in F2 and positive control groups. There were no significant differences between groups in histology examination (Kruskal Wallis test, p<0.05). The moderate score of TNF-α levels was seen in F2 and positive control groups (ANOVA/Tukey test). Similar results were seen in the collagenases assay. Conclusions: A balanced combination of areca nut and chrysanthemum extract in the oral gel can optimize the healing of traumatic oral ulcers in rats through the increase of TNF-α and collagen deposition.

Download Full-text

Biomechanical Effects of Δ9-Tetrahydrocannabinol (THC) and Cannabidiol (CBD), the Major Constituents of Cannabis, on Tendon to Tendon Healing in a Sprague Dawley Rat Achilles Tendon Surgical Repair Model

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967120s00391 ◽

2020 ◽

Vol 8 (7_suppl6) ◽

pp. 2325967120S0039

Author(s):

Chris Stauch ◽

Brittany Ammerman ◽

Michael Aynardi ◽

Matthew Garner ◽

Greg Lewis ◽

...

Keyword(s):

Achilles Tendon ◽

Surgical Repair ◽

Subcutaneous Administration ◽

Tendon Healing ◽

Tensile Load ◽

Control Group ◽

Sprague Dawley ◽

Control Groups ◽

Significant Difference ◽

Load To Failure

Objectives: Use of Cannabis is common amongst athletes and the U.S. population at large. Use of Cannabinoid Oil is being increasingly utilized for a number of different pathologies, injuries, and ailments due to anecdotal evidence of its efficacy. Due to the current United States Opioid crisis, Δ9-Tetrahydrocannabinol (THC) and Cannabidiol (CBD), the two major constituents of cannabis, are currently being evaluated as potential safer alternatives to narcotic pain medicines. The effects of recreational and/or therapeutic THC and CBD on musculoskeletal injury and healing however remain largely unknown. Our purpose was to evaluate the biomechanical effects of THC and CBD on tendon to tendon healing in a Sprague Dawley Achilles Tendon injury and surgical repair model. Methods: 33 Sprague Dawley rats were randomly assigned into control (1 ml/kg/day of vehicle containing 5% Cremaphor, 5% ethanol, and 0.9% saline n=12), THC (3 mg/kg/day n = 12), or CBD (3 mg/kg/day n=9) treatment groups. Surgical transection and repair of the Achilles tendon was performed and all rats began subcutaneous administration of their respective drug treatment the day of surgery and for 4 subsequent days, followed by sacrifice. Load to failure and stiffness were calculated from load displacement data during tensile load testing on a MTS machine. One-way ANOVA with heterogeneous variance was utilized for evaluation. Means and 95% confidence intervals were also determined. Results: The CBD group demonstrated the highest mean load to failure of 17.5 N (15.1-19.8 N), with the THC group having the second highest mean load to failure at 17.3 N (15.3-19.2 N), and the control group reporting the lowest at 15.2 N (12.1-18.3 N). No statistical difference was observed between CBD/control (p = 0.25), THC/control (p = 0.29), or CBD/THC groups (p = 0.92, Figure 1A). The THC group reported the highest mean stiffness of 3.9 N/mm (2.7-5.1 N/mm). The CBD and control groups demonstrated mean stiffness values of 3.5 N/mm (2.9-4.1 N/mm) and 3.5 N (2.7-4.3 N/mm), respectively. No statistically significant differences were observed between THC/control (p = 0.51), THC/CBD (p = 0.50), or CBD/control groups (p = 0.96) for stiffness (Figure 1B). Conclusion: Our investigation demonstrates that subcutaneous administration of CBD resulted in the highest mean load to failure while THC administration resulted in the highest mean stiffness of the three groups. This did not result however in a statistically significant difference between groups. In our small animal tendon-to-tendon repair model, use of THC or CBD did not result in decreased biomechanical characteristics, and there was a trend toward improved ultimate strength and stiffness as compared to control. Further evaluation with larger numbers of animals, and evaluating the potential synergistic effects of THC and CBD administered together are warranted. [Figure: see text]

Download Full-text

Evaluation of clinical, histology, TNF-α, and collagen expressions on oral ulcer in rats after treatment with areca nut and chrysanthemum oral gel

F1000Research ◽

10.12688/f1000research.54887.2 ◽

2021 ◽

Vol 10 ◽

pp. 623

Author(s):

Liza Meutia Sari ◽

Zaki Mubarak ◽

Dina Keumala Sari

Keyword(s):

Triamcinolone Acetonide ◽

Positive Control ◽

Flowering Plant ◽

Positive Control Group ◽

Control Group ◽

Areca Nut ◽

Sprague Dawley ◽

Control Groups ◽

Sprague Dawley Rats ◽

Tnf Α

Background: Areca nut (Areca catechu Linn.) is the seed of the fruit of the oriental palm that is commonly used among Southeast Asian communities. Chrysanthemum (Dendrathema grandiflora) is a flowering plant originating from East Asia and dominantly grows in China. Both of these plants have strong antioxidant activities. To investigate the mechanism of their wound healing activities, we prepared areca nut and chrysanthemum polyethylene oral gel and performed several in vivo assays using Sprague–Dawley rats. Methods: Sprague–Dawley rats were divided into five groups: Negative control group (rats with base gel treatment), positive control group (rats treated with triamcinolone acetonide), F1 (treatment with 20% areca nut:80% chrysanthemum), F2 (treatment with 50% areca nut:50% chrysanthemum), and F3 (treatment with 80% areca nut:20% chrysanthemum). Traumatic ulcers were performed on the buccal mucosa of all experimental animals that received topical oral gel and triamcinolone acetonide twice a day for seven days. The clinical and histological characteristics were analyzed and scored. Results: During the six days, the ulcerated area receded linearly over time and was completely cicatrized in F2, F3, and positive control group (Dependent t-test, p<0.05). There were significant increases in body weight in F2 and positive control groups. There were no significant differences between groups in histology examination (Kruskal Wallis test, p<0.05). The moderate score of TNF-α levels was seen in F2 and positive control groups (ANOVA/Tukey test, p<0.05). In the collagenases assay, a high concentration of areca nut (F3) induced the abundance of collagen during the ulcer healing process. Conclusions: The combination of areca nut and chrysanthemum extract in the oral gel can optimize the healing of traumatic oral ulcers in Sprague-Dawley rats through the increase of TNF-α and collagen deposition.

Download Full-text

Assessment of carbon dioxide, carbon dioxide/oxygen, isoflurane and pentobarbital killing methods in rats

10.1101/061002 ◽

2016 ◽

Author(s):

Jessica M Chisholm ◽

Daniel SJ Pang

Keyword(s):

Carbon Dioxide ◽

Heart Rate ◽

Loss Of Consciousness ◽

Sprague Dawley ◽

Loss Of Righting Reflex ◽

Sprague Dawley Rats ◽

General Order ◽

Righting Reflex ◽

High Concentrations ◽

The Relationship

AbstractBackground:Exposure to carbon dioxide (CO2) gas as a killing method is aversive and exposure to high concentrations likely to be painful. Bradycardia during exposure to CO2 is associated with nociception and pain. However, it is unclear if bradycardia occurs before loss of consciousness as this is variably defined in the literature. The objectives of this study were to explore the relationship between recumbency, loss of righting reflex (LORR) and a quiescent electromyograph as measures of loss of consciousness, and identify the onset of bradycardia in relation to these measures.Methods:Thirty-two adult, female Sprague-Dawley rats were instrumented with a telemetry device and randomly assigned to one of four killing methods (100% CO2, CO2 (70%)/O2 (30%), isoflurane (5%) and intraperitoneal pentobarbital (200 mg/kg). Time to achieve recumbency, LORR, quiescent electromyograph, isoelectric electrocorticograph, heart rate and apnea were recorded.Results:The general order of progression was recumbency, LORR, quiescent electromyograph, isoelectric electrocorticograph and apnea. Recumbency preceded LORR in the majority of animals (CO2; 7/8, CO2/O2; 8/8, isoflurane; 5/8, pentobarbital; 4/8). Bradycardia occurred before recumbency in the CO2 (p = 0.0002) and CO2/O2 (p = 0.005) groups, with a 50% reduction in heart rate compared to baseline. The slowest (time to apnea) and least consistent killing methods were CO2/O2 (1180 ± 658.1s) and pentobarbital (875 [239 to 4680]s).Conclusion:Bradycardia, and consequently nociception and pain, occurs before loss of consciousness during CO2 exposure. Pentobarbital displayed an unexpected lack of consistency, questioning its classification as an acceptable euthanasia method in rats.

Download Full-text

EFFECT OF VITAMIN E (α-TOCOPHEROL) ADMINISTRATION ON SPERM MOTILITY AND MORPHOLOGY OF SPRAGUE DAWLEY STRAIN RATS AFTER CISPLATIN TREATMENT

Indonesian Journal of Urology ◽

10.32421/juri.v26i1.539 ◽

2019 ◽

Vol 26 (1) ◽

Author(s):

Dimas Visa Aditya ◽

Tarmono Djojodimedjo ◽

Doddy M Soebadi

Keyword(s):

Vitamin E ◽

Sperm Motility ◽

Control Group ◽

Protective Effects ◽

Sprague Dawley ◽

Control Groups ◽

Spermatozoa Motility ◽

Sprague Dawley Rats ◽

Significant Difference ◽

Tocopherol Isomer

Objective: To evaluate the protective effects of vitamin E α-tocopherol isomer against the toxicity of cisplatin on sperm motility and morphology in Sprague Dawley rats. Material & Methods: Twenty-four rats were grouped into four groups (n=6). The control group (CN) was injected with normal saline, second group (CP) was injected with cisplatin, the third group (P1) was injected with cisplatin and vitamin E 50 mg/kgBW for 7 weeks P.O, the fourth group (P2) was injected with cisplatin and vitamin E 200 mg/kgBW for 7 weeks P.O. Vitamin E was given from 3 weeks before cisplatin injection and 4 weeks following cisplatin injection. At 7th week, all the samples were undergoing bilateral orchidectomy. Vitamin E that being used in this study was α-tocopherol isomer. Results: Cisplatin decreased motility and morphology of spermatozoa significantly against controls. Vitamin E 50 mg/kgBW and 200 mg/kgBW significantly increased motility of spermatozoa (p<0.05) compared to those in the cisplatin group only. Vitamin E 50 mg/kgBW, and 200 mg/kgBW did not have a significant difference in spermatozoa motility compare to control groups. Vitamin E 50 mg/kgBW and 200 mg/kgBW could increase the spermatozoa morphology significantly compare to those cisplatin only group. Vitamin E 50 mg/kgBW, and 200 mg/kgBW did not have a significant difference in spermatozoa morphology compared to control groups. Conclusion: α-tocopherol 50 mg/kgBW and 200 mg/kgBW provided a same protective effect against spermatozoa damage especially in motility and morphology aspect due to cisplatin exposure. Therefore, in this study it was more recommended to use α-tocopherol in 50 mg/kgBW dose than 200 mg/kgBW.

Download Full-text

Intraperitoneal injection of ketamine enhances apoptosis in urothelium via autophagy in rats

European Journal of Inflammation ◽

10.1177/2058739220935661 ◽

2020 ◽

Vol 18 ◽

pp. 205873922093566

Author(s):

Liqin Wei ◽

Jitao Wu ◽

Danxia Li ◽

Zhengfei Shan

Keyword(s):

Treatment Time ◽

Control Group ◽

Tunel Staining ◽

High Dose ◽

Sprague Dawley ◽

Control Groups ◽

Bladder Epithelium ◽

Bladder Tissue ◽

Expression Levels ◽

Sprague Dawley Rats

Ketamine abusing is associated with ulcerative cystitis, but the mechanisms remain unclear. This study aimed to investigate the existence of ketamine-induced symptom in a rat model and evaluate the underlining mechanisms. Sprague-Dawley rats were chosen and randomly divided into 12 groups (n = 8), such as the control group, low dose of ketamine (10 mg/kg/day), middle dose of ketamine (30 mg/kg/day) and high dose of ketamine (50 mg/kg/day) groups. The experimental groups were administrated ketamine i.p. daily, whereas the control groups were administrated with saline. After 1, 3, and 6 months of treatment, the bladder tissues were collected. Haematoxylin and eosin (HE) staining and a transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay were used to evaluate the bladder epithelium pathology and urothelial apoptosis, respectively. The protein expression levels of LC3, p62, Beclin1 were assessed by Western blotting. HE staining results of the experimental rats showed the bladder tissue denudation of the urothelial epithelium with edema and congestion compared with the control groups. TUNEL staining showed a significantly higher number of apoptotic cells in experimental groups than in the control groups. The protein LC3 and Beclin1 had significantly higher levels compared with control groups. The protein p62 had lower levels compared with control groups. The expression levels correlated with contraction of ketamine and treatment time. HE staining, TUNEL staining and Western blot results showed dose-dependent, time-dependent autophage in ketamine-treated rats. All the results suggested that autophagy proteins might be involved in inflammatory response in rats.

Download Full-text

Biomechanical Effects of Δ9-Tetrahydrocannabinol (THC) and Cannabidiol (CBD), the Major Constituents of Cannabis, in a Sprague Dawley Rat Achilles Tendon Surgical Repair Model

Foot & Ankle Orthopaedics ◽

10.1177/2473011420s00083 ◽

2020 ◽

Vol 5 (4) ◽

pp. 2473011420S0008

Author(s):

Chris M. Stauch ◽

Brittany Ammerman ◽

Diana E. Sepulveda ◽

Michael C. Aynardi ◽

Matthew Garner ◽

...

Keyword(s):

Achilles Tendon ◽

Surgical Repair ◽

Synergistic Effects ◽

Subcutaneous Administration ◽

Tensile Load ◽

Control Group ◽

Sprague Dawley ◽

Control Groups ◽

Significant Difference ◽

Load To Failure

Category: Sports; Hindfoot Introduction/Purpose: Use of Cannabis is common amongst athletes and the U.S. population at large. Use of Cannabinoid Oil is being increasingly utilized for a number of different pathologies, injuries, and ailments due to anecdotal evidence of its efficacy. Due to the current United States Opioid crisis, Δ9-Tetrahydrocannabinol (THC) and Cannabidiol (CBD), the two major constituents of cannabis, are currently being evaluated as potential safer alternatives to narcotic pain medicines. The effects of recreational and/or therapeutic THC and CBD on musculoskeletal injury and healing however remain largely unknown. Our purpose was to evaluate the biomechanical effects of THC and CBD on tendon to tendon healing in a Sprague Dawley Achilles Tendon injury and surgical repair model. Methods: 33 Sprague Dawley rats were randomly assigned into control (1 ml/kg/day of vehicle containing 5% Cremaphor, 5% ethanol, and 0.9% saline n=12), THC (3 mg/kg/day n = 12), or CBD (3 mg/kg/day n=9) treatment groups. Surgical transection and repair of the Achilles tendon was performed and all rats began subcutaneous administration of their respective drug treatment the day of surgery and for 4 subsequent days, followed by sacrifice. Load to failure and stiffness were calculated from load displacement data during tensile load testing on a MTS machine. One-way ANOVA with heterogeneous variance was utilized for evaluation. Means and 95% confidence intervals were also determined. Results: The CBD group demonstrated the highest mean load to failure of 17.5 N (15.1-19.8 N), with the THC group having the second highest mean load to failure at 17.3 N (15.3-19.2 N), and the control group reporting the lowest at 15.2 N (12.1-18.3 N). No statistical difference was observed between CBD/control (p = 0.25), THC/control (p = 0.29), or CBD/THC groups (p = 0.92, Figure 1A). The THC group reported the highest mean stiffness of 3.9 N/mm (2.7-5.1 N/mm). The CBD and control groups demonstrated mean stiffness values of 3.5 N/mm (2.9-4.1 N/mm) and 3.5 N (2.7-4.3 N/mm), respectively. No statistically significant differences were observed between THC/control (p = 0.51), THC/CBD (p = 0.50), or CBD/control groups (p = 0.96) for stiffness (Figure 1B). Conclusion: Our investigation demonstrates that subcutaneous administration of CBD resulted in the highest mean load to failure, while THC administration resulted in the highest mean stiffness of the three groups. This did not result however in a statistically significant difference between groups. In our small animal tendon-to-tendon repair model, use of THC or CBD did not result in decreased biomechanical characteristics, and there was a trend toward improved ultimate strength and stiffness as compared to control. Further evaluation with larger numbers of animals, and evaluating the potential synergistic effects of THC and CBD administered together are warranted.

Download Full-text