|Budget Amount *help
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1993: ¥1,500,000 (Direct Cost: ¥1,500,000)
Glycine (Gly) or gamma-amino butyric acid (GABA) is considered to be the main inhibitory neurotransmitter in the brain stem, which is the frimary center of the motor and sensation in the dental field. The Xenopus oocyte transration systme was used to study the rapid membrane effects of steroids and these metabolites on the GABA or Gly response. The brain stem of adult rat was divided into four parts, interbrain, midbrain, pons and spinal cord. From each part, mRNA was extracted and was injected into the oocytes. Two to three days after the injection, Gly or GABA response was investigated under ordinary voltage clamp condition. Gly response was not affected with any streroids. But, GABA response was inhibited with steroid hormones, testosterone, progesterone, estradiol and others, only in high concentration. On the other side, steroid hormone metabolites, 2alpha-hydroxy-5alpha-pregnan-20-one (THP) and 3alpha, 21-dihydroxy-5alpha-pregnan-20-one (THDOC), potentiated GABA (10muM) response remarkably at rather low concentration (>10 nM). THP is the metabolite of progesterone which concentration in blood varies considerably with the menstrual cycles. And most anaesthetics cause these effect by binding the GABA receptors. These suggest that the effect of anesthetics can be influenced by the menstrual cycles. So, the menstrul cycle of the patient should be taken into the consideration in the dental anesthesia.