Zinc modulates the electro-olfactogram of the frog.
OBJECTIVE
Zinc is considered an important element in olfaction, however, its exact role is still unclear. A large amount of zinc is contained in the olfactory mucosa, so Zn(2+) may behave as a neuromodulator, as in the hippocampus. To reveal the acute effects of Zn(2+) on olfactory mucosa, electro-olfactograms (EOG) were recorded with or without Zn(2+).


METHODS
The isolated olfactory mucosa of a bullfrog (Rana catesbiana) was set in an EOG recording chamber and bathed in Ringer's solution. Effects of ZnSO(4) (25 microM) on EOGs were examined. Four types of stimulants, n-amyl acetate (200 microM), menthone (10 microM), forskolin (2 microM), and 3-isobutil-methylxisanthine (IBMX, 100 microM) were tested.


RESULTS
Zn(2+) (25 microM) charged with the ciliated surface of the olfactory mucosa attenuates EOGs which were produced not only by odorants but also by forskolin and IBMX. The attenuating ratios of EOGs for stimulants were as follows; n-amyl acetate (0.51+/-0.18, n=4), menthone (0.48+/-0.28, n=4), forskolin (0.61+/-0.16, n=4), and IBMX (0.68+/-0.19, n=4); (mean+/-S.D.). These attenuations were reversible. The results indicate that Zn(2+) may block the c-AMP dependent transduction channels of the olfactory cells.


CONCLUSIONS
Micro molar Zn(2+) attenuates EOG of the frog. Zn(2+) may be thought to behave as one of the modulators in olfactory reception.
Ishimaru
T
T
Department of Otorhinolaryngology, School of Medicine, Kanazawa University, 13-1, Takara-machi, Kanazawa, Japan. ishimar@orl.m.kanazawa-u.ac.jp
Tsukatani
T
T
Miwa
T
T
Furukawa
M
M
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D005576:Colforsin / Q000494:pharmacology; D004594:Electrophysiology; D066298:In Vitro Techniques; D008610:Menthol; D009812:Odorants; D009831:Olfactory Mucosa / Q000187:drug effects* / Q000502:physiology*; D000439:Pentanols / Q000494:pharmacology; D011892:Rana catesbeiana; D013729:Terpenes / Q000494:pharmacology; D015032:Zinc / Q000494:pharmacology*
D000439:Pentanols; D013729:Terpenes; D008610:Menthol; D005576:Colforsin; C005716:amyl acetate; C019466:menthone; D015032:Zinc; D015056:1-Methyl-3-isobutylxanthine