Gene expression and histopathological evaluation of thiamine pyrophosphate on optic neuropathy induced with ethambutol in rats.
OBJECTIVE
To compare the effects of thiamine pyrophosphate (TPP) and thiamine (TM) in oxidative optic neuropathy in rats induced by ethambutol.


METHODS
The animals were divided into four groups: a control group (CG), an ethambutol control (ETC) group, TM plus ethambutol group (TMG), and TPP plus ethambutol group (TPPG). One hour after intraperitoneal administration of TM 20 mg/kg to the TMG group and TPP 20 mg/kg to TPPG group, 30 mg/kg ethambutol was givenviagavage to all the groups but the CG. This procedure was repeated once daily for 90d. After that period, all rats were exposed to high levels of anaesthesia in order to investigate the gene expression of malondialdehyde and glutathione in removed optic nerve tissue and histopathologically to examine these tissues.


RESULTS
Malondialdehyde gene expression significantly increased, whereas glutathione gene expression significantly decreased in the ETC group compared to the CG. TM could not prevent the increase of malondialdehyde gene expression and the decrease of glutathione, while TPP significantly could suppress. Histopathologically, significant vacuolization in the optic nerve, single-cell necrosis in the glial cells, and a decrease in oligodendrocytes were observed in the ETC group. Vacuolization in the optic nerve, a decrease in oligodendrocytes and single-cell necrosis were found in the TMG group, while no pathological finding was observed in the TPPG group except for mild vacuolization.


CONCLUSIONS
TPP protects the optic nerve against the ethambutol-induced toxicity but TM does not. TPP can be beneficial in prophilaxis of optic neuropathy in ethambutol therapy.
Department of Ophthalmology, Erzurum Region Education and Research Hospital, Erzurum 25100, Turkey.
Emine
E
Cinici
Department of Pharmacology, Faculty of Medicine, Erzincan University, Erzincan 24030, Turkey.
Nihal
N
Cetin
Department of Pharmacology, Faculty of Medicine, Erzincan University, Erzincan 24030, Turkey.
Bahadir
B
Suleyman
Department of Pharmacology, Faculty of Medicine, Erzincan University, Erzincan 24030, Turkey.
Durdu
D
Altuner
Department of Medical Genetics, Goztepe Training and Research Hospital, Istanbul Medeniyet University, Istanbul 34730, Turkey.
Oguzhan
O
Yarali
Department of Pathology, Erzurum Region Education and Research Hospital, Erzurum 25100, Turkey.
Hilal
H
Balta
Department of Pathology, Erzurum Region Education and Research Hospital, Erzurum 25100, Turkey.
Ilknur
I
Calik
Department of Histology and Embryology, Faculty of Medicine, Recep Tayyip Erdoğan University, Rize 53100, Turkey.
Levent
L
Tumkaya
Department of Pharmacology, Faculty of Medicine, Erzincan University, Erzincan 24030, Turkey.
Halis
H
Suleyman
ethambutol; gene expression; optic neuropathy; rat; thiamine pyrophosphate