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    The effects of hydergine on the synaptic plasticity of aged rats
    (1994) Hariri N.; Falakali B.; Algan O.
    Contradictory results have been reported in different brain regions with regard to age-related morphological ranges. In the present study, the number of synapses (Nv), the mean synaptic length (S), and the total synaptic length of synapses/micrograph (Sv) were measured using quantitative morphometric techniques in E-PTA stained sections of the olfactory bulb from adult (12 months), old (30 months), and Hydregine-treated old (30 months) rats. In old animals, Nv and Sv were reduced; however, S was significantly increased when compared with adults. Hydergine (Codergocrine mesylate) treatment of old animals (3 mg/kg/b.w./day for 4 weeks) influenced these parameters differently: in old Hydergine-treated animals, Sv and Nv were higher and S was significantly smaller, when compared with the untreated old group. All the parameters studied were not statistically different when Hydergine-treated old rats were compared with adult animals. The present findings have been interpreted as a modulating effect of Hydergine on the morphological plasticity of the olfactory bulb synapses.
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    Modulation of the spinal motoneuronal reactions by intrasegmental somatostatin in rats
    (1999) Demirgoren S.; Hariri N.; Uyar M.; Yegul I.; Celebi G.; Pilyavskii A.
    Motor dysfunction is the side effect of intrathecal somatostatin (STT) administration which has been postulated to be related with the direct toxic effect of STT on spinal motoneurones. In order to differentiate the effects of STT on spinal interneurones and motoneurones, changes in monosynaptic (MR), polysynaptic (PR1, PR2) and flexion (FR) reflex responses of L5 ventral root after STT microinjections into the dorsal or ventral horn of the spinal cord were studied in the rat. MR, PR1 and PR2 were evoked by high threshold stimulation of the dorsal root and FR by subcutaneous stimulation of hind paw. Microinjections of STT (10, 50, 100 µM in 0.5 µL) reversibly depressed PR1, PR2 and FR when injected either into the dorsal or ventral horn. 500 µM STT depressed PR1 and PR2 after injected into the dorsal horn, whereas STT at 500 µM concentration evoked facilitation of PR1 and PR2 when administered into the ventral horn. STT-evoked depression of PR2 and FR was accompanied by a reduction in duration and an increase in latency. STT did not induce considerable changes in MR in present experiments. Our data have shown that intrasegmental STT administrations did not significantly influence spinal motoneurones, but provided evidence that interneuron are the main group of cell-target for STT, a finding which is in line with the previous evidence that STT may modulate transmission of the secondary signals in the spinal cord.