Inhibitory effect of intrathecal glycine on the micturition reflex in normal and spinal cord injury rats.
We examined the influence of lumbosacral glycinergic neurons on the spinobulbospinal and spinal micturition reflexes. Female rats were divided into intact rats, rats with acute injury to the lower thoracic spinal cord (SCI), and rats with chronic SCI. Under urethane anesthesia, isovolumetric cystometry was performed in each group before and after intrathecal (IT) injection of glycine or strychnine into the lumbosacral cord level. The glutamate and glycine levels of the lumbosacral cord were measured after injection of glycine or strychnine in intact and chronic SCI rats. Expression of strychnine-sensitive glycine receptor alpha-1 (GlyR alpha1) mRNA in the lumbosacral cord was also assessed in both rats. In chronic SCI rats, the interval and amplitude of bladder contractions were shorter and smaller when compared with intact rats. IT glycine (0.1-100 microg) prolonged the interval and decreased the amplitude of bladder contractions in both intact rats and chronic SCI rats. IT strychnine (0.01-10 microg) elevated the baseline pressure in intact rats and induced bladder contraction in acute SCI rats. On amino acid analysis, IT glycine (0.01-100 microg) decreased the glutamate level of the lumbosacral cord in intact rats, but not in chronic SCI rats. The glycine level of the lumbosacral cord was 54% lower in chronic SCI rats when compared with intact rats, while the GlyR alpha1 mRNA level did not change after SCI. These results suggest that glycinergic neurons may have an important inhibitory effect on the spinobulbospinal and spinal micturition reflexes at the level of the lumbosacral cord.
Miyazato
Minoru
M
Department of Urology, Faculty of Medicine, University of the Ryukyus, Okinawa 903-0215, Japan.
Sugaya
Kimio
K
Nishijima
Saori
S
Ashitomi
Katsuhiro
K
Hatano
Tadashi
T
Ogawa
Yoshihide
Y
D000208:Acute Disease; D000818:Animals; D002908:Chronic Disease; D004195:Disease Models, Animal; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism; D005998:Glycine / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D018684:Glycine Agents / Q000008:administration & dosage / Q000494:pharmacology; D007278:Injections, Spinal; D008161:Lumbosacral Region; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018009:Receptors, Glycine / Q000235:genetics; D012018:Reflex / Q000187:drug effects*; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D013331:Strychnine / Q000008:administration & dosage / Q000494:pharmacology; D001743:Urinary Bladder / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology; D014554:Urination / Q000187:drug effects*
D018684:Glycine Agents; D012333:RNA, Messenger; D018009:Receptors, Glycine; D018698:Glutamic Acid; D013331:Strychnine; D005998:Glycine