Presynaptic Mechanism Underlying Regulation of Transmitter Release by G Protein Coupled Receptors

A variety of G protein coupled receptors (GPCRs) are expressed in the presynaptic terminals of central and peripheral synapses and play regulatory roles in transmitter release. The patch-clamp whole-cell recording technique, applied to the calyx of Held presynaptic terminal in brainstem slices of rodents, has made it possible to directly examine intracellular mechanisms underlying the GPCR-mediated presynaptic inhibition. At the calyx of Held, bath-application of agonists for GPCRs such as GABAB receptors, group III metabotropic glutamate receptors (mGluRs), adenosine A1 receptors, or adrenaline alpha2 receptors, attenuate evoked transmitter release via inhibiting voltage-activated Ca2+ currents without affecting voltage-activated K+ currents or inwardly rectifying K+ currents. Furthermore, inhibition of voltage-activated Ca2+ currents fully explains the magnitude of GPCR-mediated presynaptic inhibition, indicating no essential involvement of exocytotic mechanisms in the downstream of Ca2+ influx. Direct loadings of G protein beta gamma subunit (G beta gamma) into the calyceal terminal mimic and occlude the inhibitory effect of a GPCR agonist on presynaptic Ca2+ currents (IpCa), suggesting that G beta gammamediates presynaptic inhibition by GPCRs. Among presynaptic GPCRs glutamate and adenosine autoreceptors play regulatory roles in transmitter release during early postnatal period when the release probability (p) is high, but these functions are lost concomitantly with a decrease in p during postnatal development.

Clinical study on the prevention of recurrent tonshillitis by acupuncture (III) / 全日本鍼灸学会雑誌

We have conducted acupuncture treatment for prevening the relapse of recurrent tonsillitis. We previously noted the effectiveness of this treatment in 121 of 239 patients treated in 1980, especially in elementary school children. In the present study, we compared the annual days of absence from school and the body dimensions of children with tonsillitis given acupuncture treatment with those having tonsillar hypertrophy chosen by a school study, although there is a question on the latter's propriety as a control group in a strict sense, in order to investigate the degree of spontaneous healing included in the preventive effects of acupuncture treatment on the relapse of recurrent tonsillitis.<br>By May 1983, our reseach was completed in 22 children with tonsillitis given acupuncture treatment and 19 with tonsillar hypertrophy not given such therapy. In children with tonsillitis given acupuncture treatment, the average annual days of absence from school before treatment was 14.0, which was more than that for all children in the S elementary school, and that in the year after treatment was 6.5, approximating that for all children in the school. In children with tonsillar hypertrophy not given acupuncture treatment, the average number of days of absence was close to that for all children in the S elementary school in both years.<br>Among 14 children with tonsillitis given acupuncture treatment, lower values of height and weight were noted in eight and 12 children, respectively, at the beginning of treatment, as compared with the national averages. The body dimensions of children with tonsillar hypertrophy not given acupuncture treatment were similar to the national averages. Of 14 children with tonsillitis given acupuncture treatment, an increase to a value exceeding the national average was observed with both the height and weight in six children, the height in two and the weight in one within the year after treatment.<br>The above results show that children with tonsillitis have a problem from the educational and developmental standpoint, even if they do not have a focal tonsil. We think that acupuncture treatment is worth attempting prior to tonsillectomy, although it is not so surely effective as tonsillectomy, when the severity of operative stress on the living body due to tonsillectomy and the burden of medical expenses and the load on the patient's family caused by hospitalization are taken into consideration.