title: Liposome-encapsulated hemoglobin alleviates hearing loss after transient cochlear ischemia and reperfusion in the gerbil.
abstract: To test liposome-encapsulated hemoglobin (LEH) in transient cochlear ischemia/reperfusion as a model of sudden deafness, Mongolian gerbils were randomly assigned to receive 2 mL/kg of either low-affinity LEH (l-LEH, P₅₀0₂ = 40 mm Hg), high-affinity LEH (h-LEH, P₅₀0₂ = 10 mm Hg), homologous red blood cells (RBCs), or saline (each group n = 6) 30 min before 15-min occlusion of the bilateral vertebral arteries and reperfusion. Sequential changes in hearing were assessed by auditory brain response 1, 4, and 7 days after ischemia/reperfusion, when the animals were sacrificed for pathological studies. h-LEH was significantly more protective than l-LEH in suppressing hearing loss, in contrast to RBC or saline treatment, at 8, 16, and 32 kHz, where hearing loss was most severe (P < 0.05 between any two groups) on the first day after cochlear ischemia/reperfusion. Thereafter, hearing loss improved gradually in all groups, with a significant difference among groups up to 7 days, when morphological studies revealed that the inner hair cells but not the outer hair cells, were significantly lost in the groups in the same order. The results suggest that pretreatment with h-LEH is significantly more protective than l-LEH in mitigating hearing loss and underlying pathological damage, in contrast to transfusion or saline infusion 7 days after transient cochlear ischemia/reperfusion.
authors.affiliation: Ehime University Graduate School of Medicine, Otolaryngology Shitsukawa, Toon, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okada
authors.forename: Akira T
authors.initials: AT
authors.lastname: Kawaguchi
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Hakuba
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Takeda
authors.forename: Jun
authors.initials: J
authors.lastname: Hyodo
authors.forename: Kiyohiro
authors.initials: K
authors.lastname: Imai
authors.forename: Naohito
authors.initials: N
authors.lastname: Hato
authors.forename: Kiyofumi
authors.initials: K
authors.lastname: Gyo
mesh_terms: D000818:Animals; D001802:Blood Substitutes / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D003051:Cochlea / Q000187:drug effects* / Q000473:pathology; D005849:Gerbillinae; D034381:Hearing Loss / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D008081:Liposomes; D008297:Male; D011897:Random Allocation; D015427:Reperfusion Injury / Q000188:drug therapy* / Q000473:pathology
chemical_list: D001802:Blood Substitutes; D008081:Liposomes