| Abstract: | The in vivo effects of (+/-) baclofen (10(-6)-10(-4) M), muscimol (10(-5)-10(-4) M), and (+) bicuculline (10(-4)-10(-3) M) applications on evoked potentials in the olfactory bulb (OB) and primordial hippoccamp (PH) were studied in frogs. Baclofen was found to decrease drastically postsynaptic components of OB orthodromic potential and to slightly increase OB antidromic potential. Muscimol decreased only the second component of OB orthodromic potential and OB antidromic potential. Baclofen and muscimol decreased all the components of PH orthodromic potential, but for the first positive one. All the effects were reversible and dose-dependent. Bicuculline antagonized muscimol effects, without affecting baclofen effects in both structures under study. The results suggest the presence of two types of GABA-receptors in OB and PH of frogs. GAGAB-receptors are shown to be located on the primary olfactory afferents and to be responsible for presynaptic inhibition in OB. |
