[Changes in centrally released arginine vasopressin by stimulation of the medullary reticular formation].
It has been reported that after 40 minutes of stimulation of the medullary reticular formation (MORF), widespread significant increase by 1.4% to 2.8% in brain water content occurs in white matter of the injured hemisphere. Recent studies indicate that centrally released arginine vasopressin (AVP) influences water permeability of the brain in both normal and pathological conditions. The present study was carried out to clarify the effect of electrical stimulation of MORF on centrally released AVP. The cats were divided into three groups. In group A (16 cats), electrical stimulation of MORF (1msec, 5V, 50Hz) was carried out for 80 minutes in normal cats. In group B (11 cats), stimulation was started 17 hours after cold injury under the same conditions and carried out for 80 minutes. In group C (10 cats), angiotensin II was administered to elevate blood pressure to the same degree as during MORF stimulation 17 hours after cold injury. AVP concentrations in the cerebrospinal fluid (CSF), plasma and brain tissue of the injured and non-injured white matter were measured by radioimmunoassay. Plasma osmolality was also determined by the freezing point depression method. Normal values (mean +/- S. D.) of CSF and plasma AVP were 4.0 +/- 2.2 and 9.9 +/- 3.6 pg/ml respectively. Plasma AVP and osmolality did not show significant changes before and at the end of experiments in all groups. There were no significant changes in CSF AVP by induced hypertension for 80 minutes (Group C). Stimulation of the medullary reticular formation resulted in significant and progressive increase in CSF AVP in normal and injured brain (Group A, B).(ABSTRACT TRUNCATED AT 250 WORDS)
Kuniyoshi
T
T
Department of Neurological Surgery, Kagawa Medical School, Japan.
D000818:Animals; D001127:Arginine Vasopressin / Q000134:cerebrospinal fluid / Q000378:metabolism*; D001794:Blood Pressure; D001834:Body Water / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D001929:Brain Edema / Q000209:etiology; D002415:Cats; D004558:Electric Stimulation; D007427:Intracranial Pressure; D008526:Medulla Oblongata / Q000502:physiology*; D012154:Reticular Formation / Q000502:physiology*
D001127:Arginine Vasopressin