Effect of Levobupivacaine Hydrochloride-Loaded Nanospheres on Delayed Cerebral Vasospasm Following Subarachnoid Hemorrhage in Rabbits

Abstract

This research was aimed to analyze the mechanism of action of levobupivacaine hydrochloride-loaded nanospheres on delayed cerebral vasospasm following subarachnoid hemorrhage (SAH). Levobupivacaine hydrochloride-loaded nanospheres (LevoBPV Hcl/PLGA) were prepared using the solvent evaporation methodology, with the raw material as a control. The blood drug concentrations were detected by HPLC after subcutaneous and subarachnoid administration in experimental rabbits. Forty New Zealand white rabbits were randomly assigned into Sham group, SAH group, LevoBPV Hcl group (10 mg/kg), and LevoBPV Hcl/PLGA group (10 mg/kg), with 10 rabbits in each group. The SAH model was induced using the double blood injection methodology combined with internal carotid artery ligation. Brain tissue samples were collected on day 7 for pathological characterization, determination of neuronal apoptosis, and measurement of basilar artery diameter and area. The levels of oxidative stress factors (superoxide (SOD), malondiadehyde (MDA), glutathione peroxidase (GSH-Px)) and vasoconstrictor factors (nitric oxide (NO), endothelin-1 (ET-1)) in the cerebrospinal fluid (CSF) were detected using assay kits. The results revealed that the drug loading capacity of LevoBPV Hcl/PLGA was 29.13%, encapsulation efficiency was 87.09%, and the average particle size was 81.43 μm. Under the same dosage, both subcutaneous and subarachnoid administration of LevoBPV Hcl/PLGA exhibited two concentration peaks in the blood drug concentration, with lower concentration values versus LevoBPV Hcl group, and a longer average residence time than LevoBPV Hcl group (P < 0.05). Relative to Sham group, SAH group exhibited decreased diameter and area of the basilar artery, reduced neuronal density, increased neuronal apoptosis rate, decreased levels of SOD, GSH-Px, and NO in the CSF, and increased levels of MDA and ET-1 (P < 0.05). Moreover, LevoBPV Hcl group and LevoBPV Hcl/PLGA group showed increased diameter and area of the basilar artery, higher neuronal density, reduced neuronal apoptosis rate, elevated levels of SOD, GSH-Px, and NO in the CSF, and decreased levels of MDA and ET-1 versus SAH group (P < 0.05). The LevoBPV Hcl/PLGA group exhibited increased diameter and area of the basilar artery, higher neuronal density, reduced neuronal apoptosis rate, elevated levels of SOD, GSH-Px, and NO in the CSF, and decreased levels of MDA and ET-1 versus LevoBPV Hcl group (P < 0.05). In short, LevoBPV HCl-loaded nanospheres can prolong the in vivo residence time of subcutaneous and subarachnoid administration, reduce the maximum blood drug concentration, and enhance drug safety. Furthermore, these nanospheres can inhibit neuronal apoptosis following SAH, regulate oxidative stress and vasoconstrictor factor expression, thereby suppressing the occurrence of delayed cerebral vasospasm and alleviating brain tissue damage.