Protective Effect of Supplementation with Lycium ruthenicum Murray Extract on Exhaustive Exercise-Induced Cardiac Injury in Rats
Introduction
Lycium ruthenicum Murray, a member of the Solanaceae family, is a resilient plant species predominantly found in saline desert regions of Qinghai and Xinjiang, China. Known for its high anthocyanin content, this plant has garnered attention for its pharmacological properties, including antioxidant, anti-fatigue, and hypoglycemic activities. Anthocyanins, a subclass of flavonols, are potent antioxidants that protect plants against reactive oxygen species (ROS) and environmental stressors. In recent years, research has explored their potential therapeutic applications in mitigating oxidative stress-related damage in mammals.
Exhaustive exercise, while beneficial in moderation, can induce excessive oxidative stress, leading to cellular damage in organs such as the heart. This stress arises from an imbalance between ROS production and the body’s antioxidant defense mechanisms. Elevated ROS levels during intense physical activity contribute to inflammation, tissue injury, and markers of cardiac damage, such as creatine kinase isoenzyme MB (CK-MB). Antioxidant supplementation has emerged as a strategy to counteract these effects. The present study investigates the cardioprotective role of L. ruthenicum extract, rich in anthocyanins, in alleviating exhaustive exercise-induced cardiac injury in Sprague-Dawley (SD) rats.
Materials and Methods
Plant Extract Preparation and Anthocyanin Quantification
L. ruthenicum extract was prepared, and its anthocyanin content was quantified using the Nakata method. The extract contained 24.1 ± 7.7 mg of anthocyanins per gram, confirming its suitability for evaluating antioxidant effects.
Experimental Design
Thirty male SD rats (6 weeks old) were randomly divided into five groups:
- Control group: No exercise or supplementation.
- Exhaustive exercise group: Subjected to treadmill running until exhaustion without supplementation.
- Anthocyanin group: Received 5 mg/rat of pure anthocyanin daily for 7 days before exercise.
- Low-dose L. ruthenicum group: Received 10 mg/rat of extract daily for 7 days before exercise.
- High-dose L. ruthenicum group: Received 30 mg/rat of extract daily for 7 days before exercise.
Exercise Protocol
Rats underwent a graded treadmill running protocol starting at a 10% incline and 15 m/min for 10 minutes. Speed and duration were incrementally increased to 25 m/min (20 minutes), 28 m/min (20 minutes), 31 m/min (20 minutes), 34 m/min (20 minutes), and 37 m/min (20 minutes) until exhaustion, defined as the inability to continue running despite mild electrical stimulation.
Sample Collection and Analysis
Post-exercise, blood samples were collected to measure serum nitrate (NO), ROS, interleukin (IL)-1, IL-6, and CK-MB levels. Heart tissues were excised, fixed in formalin, and stained with hematoxylin and eosin (H&E) for histopathological examination under 400× magnification.
Key Findings
Biochemical Markers of Oxidative Stress and Inflammation
Exhaustive exercise significantly elevated serum NO and ROS levels in untreated rats, indicating oxidative stress. However, pretreatment with L. ruthenicum extract at both 10 mg and 30 mg doses markedly reduced these levels (P < 0.05). The high-dose group showed a more pronounced reduction, comparable to the anthocyanin-positive control group. Similarly, pro-inflammatory cytokines IL-1 and IL-6, which were elevated post-exercise, were significantly suppressed by L. ruthenicum supplementation (P < 0.05).
Cardiac Damage Assessment
CK-MB, a biomarker of myocardial injury, increased substantially in the exhaustive exercise group. Both doses of L. ruthenicum extract significantly attenuated CK-MB elevation (P < 0.05), with the 30 mg dose demonstrating efficacy similar to anthocyanin supplementation. These results suggest that the extract mitigates exercise-induced cardiac damage by preserving myocardial integrity.
Histopathological Observations
Histological analysis of heart tissues revealed severe damage in the exhaustive exercise group, characterized by vacuolation (indicative of cellular edema) and necrotic cells with pyknotic nuclei (Figure 1B). In contrast, rats pretreated with L. ruthenicum extract exhibited minimal vacuolation and reduced cell death (Figure 1D). The anthocyanin group also showed protective effects (Figure 1C), though the extent of preservation was analogous to the high-dose L. ruthenicum group. These findings confirm that L. ruthenicum supplementation ameliorates structural damage to cardiac tissue caused by exhaustive exercise.
Mechanistic Insights
The cardioprotective effects of L. ruthenicum are attributed to its high anthocyanin content, which scavenges ROS and reduces oxidative stress. Anthocyanins neutralize free radicals generated during intense exercise, thereby preventing lipid peroxidation and cellular membrane damage. Additionally, the suppression of IL-1 and IL-6 highlights the extract’s anti-inflammatory properties, which further protect cardiac tissue from exercise-induced injury.
Dose-Response Relationship
A dose-dependent effect was observed, with the 30 mg dose of L. ruthenicum extract demonstrating superior efficacy compared to the 10 mg dose. This aligns with the anthocyanin group’s results, reinforcing the role of anthocyanins as the primary bioactive compounds responsible for the observed benefits.
Limitations and Future Directions
While the study establishes the protective role of L. ruthenicum extract, the exact molecular mechanisms remain unexplored. Future research should investigate signaling pathways involved in antioxidant and anti-inflammatory responses, such as nuclear factor-kappa B (NF-κB) or nuclear factor erythroid 2-related factor 2 (Nrf2). Long-term supplementation studies and clinical trials are also warranted to validate these findings in humans.
Conclusion
Seven-day supplementation with Lycium ruthenicum Murray extract significantly attenuates exhaustive exercise-induced cardiac injury in rats by reducing oxidative stress, inflammation, and myocardial damage. The high anthocyanin content of the extract underpins its antioxidant capacity, which preserves cardiac function and tissue integrity. These findings highlight the potential of L. ruthenicum as a natural therapeutic agent for mitigating exercise-related oxidative stress, though further mechanistic studies are essential to fully elucidate its cardioprotective pathways.
doi.org/10.1097/CM9.0000000000000185
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