The effects of Ca2+-free perfusion medium on excitatory postsynaptic currents (EPSCs) and potentials (EPSPs) were studied by whole-cell recordings from neurons of the supraoptic nucleus (SON) in trimmed slice preparations of mouse hypothalamus. EPSCs evoked with either focal stimulation to the SON or perfusion of slices with high K+-medium, spontaneous EPSCs (sEPSCs) and miniature EPSCs (mEPSCs) recorded from neurons of the SON were blocked by the glutamate receptor antagonist kynurenic acid (1 mM). While EPSCs evoked by focal stimulation were abolished in the presence of Ca2+-free perfusion medium; sEPSCs and mEPSCs remained. Neither the frequency nor the amplitude of the sEPSCs and mEPSCs significantly changed during the application of Ca2+-free perfusion medium. Perfusion of slices with high K+-medium increased the mEPSC frequency compared with that recorded in normal Ca2+-containing perfusion medium. In contrast, mEPSC frequency did not change during perfusion with Ca2+-free high K+-medium. In current-clamp mode sEPSPs were observed during the perfusion with Ca2+-free medium. Some sEPSPs recorded in Ca2+-free medium were sufficiently large to evoke action potentials. These results imply that spontaneous glutamatergic synaptic inputs to the hypothalamic neurosecretory cells exist in Ca2+-free perfusion medium. Thus, the present study suggests that Ca2+-free medium does not always block the synaptic transmission in hypothalamic slice preparations.
The effects of severing the hypoglossal nerve and resultant restriction of tongue movement was evaluated for its effect on masticatory jaw movement. Electromyograms of masseter muscles in the feeding rat were recorded 3 days after the nerve severing operation at 1 week intervals. Even after severing the lateral branches of the hypoglossal nerve bilaterally, active-feeding behaviour continued with mastication slightly impaired. After severing the medical branches bilaterally, feeding behaviour was rarely observed, but where eating did take place mastication was impaired with marked disturbance in the masticatory rhythm.
Purpose: To determine whether cerebral metabolic and circulatory consequences of N20 result from activation of the sympathoadrenal system. The effects of pretreatment with intradstemal injection of 6-OHDA, which produces chemical sympathectomy, were studied in dogs.
was a great difference in peak pQsition between Lat − and Med − Hyo reflex discharges . On the other hand , there was little difference in the peak position between Lat − and Med − Gen reflexes . 5 . Discharge durations were generally longer by Med stimulation than by Lat stimulation . Ratlo of the duration by Lat stimulation to that by Med stimulatlon was the greatest in Gen reflex , while it was the smallest in Hyo reflex . 6 , In general , quantities of discharges by Med stimulation were greater than those by Lat stimulation . Ratio of the quantity of discharges by Lat stimulation to that by Med stimulation was smaller in Hyo and Int reflexes than in Gen reflex . In Hyo and Int reflexes , a rapid decrease in the quantity was seen with a decreasing intensity of Lat stimulation , whereas in Gen reflex , the similar decrement of discharges was observed by Med stimulation . 7. From these results , it is supposed that a monosynaptic reflex pathway is involved in Med − Hyo reflex , and that in Hyo and Int reflexes , a greater quantity of afferent inputs is brought from Med , while in Gen reflex , the afferent input source from Lat is relative 正 y greater than the other Hyo and Int reflexes .
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