Increased Efficacy of Antivenom Combined with Hyperbaric Oxygen on Envenomation in Adult Rats

Background: Snakebites are a neglected threat to global human health with a high morbidity rate. The present study explored the efficacy of antivenom with hyperbaric oxygen (HBO) intervention on snakebites, which could provide the experimental basis for clinical adjuvant therapy.

Methods: Male Sprague-Dawley rats (n = 96) were randomized into four groups: the poison model was established by injecting Deinagkistrodon acutus (D. acutus) venom (0.8 LD50) via the caudal vein; the antivenom group was injected immediately with specific antivenom via the caudal vein after successful establishment of the envenomation model; and the antivenom + HBO group was exposed to HBO environment for 1 h once at predetermined periods of 0 h, 4 h, 12 h, and 23 h after antivenin administration. Each HBO time point had six rats; the control group was left untreated. The rats in the experimental group were euthanized at the corresponding time points after HBO therapy, and brain tissue and blood were harvested immediately. Hematoxylin and eosin (H&E) staining was used to investigate the pathological changes in the rat brain. Immunohistochemistry (IHC), real-time polymerase chain reaction (PCR), and Western blotting were used to detect the expression of Nestin mRNA and protein in the subventricular zone (SVZ) of the brain. The levels of coagulation function (prothrombin time, activated partial thromboplastin time [APTT], and fibrinogen) and oxidation/antioxidation index (malondialdehyde [MDA] and superoxide dismutase [SOD]) were analyzed. Data were analyzed using one-way analysis of variance.

Results: The brain tissue from rats in the poison model was observed for pathological changes using H&E staining. Tissues showed edema, decreased cell number, and disordered arrangement in the SVZ in the snake venom group. The antivenom - HBO intervention significantly alleviated these observations and was more prominent in the antivenom + HBO group. The serum levels of SOD and MDA in the snake venom group were increased and the antivenom - HBO intervention further increased the SOD levels but significantly decreased the MDA levels; however, this was enhanced within 1 h after HBO administration (MDA: F = 5.540, P = 0.008, SOD: F = 7.361, P = 0.000). Activated partial thromboplastin time (APTT) was significantly abnormal after venom administration but improved after antivenom and was even more significant in the antivenom + HBO group 5 h after envenomation (F = 25.430, P = 0.000). Only a few nestin-positive cells were observed in the envenomation model. The expression levels were significant in the antivenom and antivenom + HBO groups within 1 and 5 h after envenomation and were more significant in the antivenom + HBO group as determined by IHC, real-time PCR, and Western blotting (P < 0.05). D. acutus envenomation has neurotoxic effects in the brain of rats.

Conclusions: Antivenin and HBO, respectively, induced a neuroprotective effect after D. acutus envenomation by attenuating brain edema, upregulating nestin expression in SVZ, and improving coagulopathy and oxidative stress. The intervention efficacy of antivenom with HBO was maximum within 5 h after envenomation and was more efficacious than antivenom alone.