Hippocampal levels of dynorphin A (1-8) in neonatal and 16-week-old spontaneously hypertensive rats: comparisons with DOCA-salt hypertension.
In this study the possible role of hippocampal dynorphin in the development of hypertension in spontaneously hypertensive rats (SHR) was investigated by determining dynorphin A (1-8) (DN A (1-8] levels in hippocampus in 16 week old SRH, Wistar Kyoto (WKY) controls and SHR treated with antihypertensive drugs as well as DOCA-salt hypertensive Sprague Dawley (SD) rats, using radioimmunoassay (RIA). We found that DN A (1-8) was decreased significantly in both dorsal (-68%) and ventral (-58%) hippocampus in SHR compared with WKY rats. Treatment with hydralazine and guanethidine (25 mg/kg/24 hr of each drug in drinking water) for 8 weeks to prevent the development of hypertension in young SHR had no effect on this low hippocampal dynorphin level. We failed to find significant changes in hippocampal DN A (1-8) level in DOCA-salt hypertensive rats. The low level of hippocampal dynorphin existed before the development of hypertension in 6 day neonatal SHR (-73%). Hippocampal Met-enkephalin was unchanged in all experimental groups except for a slight decrease in neonatal SHR. The results establish a genetic difference in the hippocampal dynorphin system of SHR compared with WKY, the significance of which, for the development of hypertension, remains to be investigated.
Li
S J
SJ
Department of Pharmacology, School of Medicine, East Carolina University, Greenville 27858-4354.
Hong
J S
JS
Ingenito
A J
AJ
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D000959:Antihypertensive Agents / Q000627:therapeutic use; D003900:Desoxycorticosterone; D004195:Disease Models, Animal; D004399:Dynorphins / Q000378:metabolism*; D004744:Enkephalin, Methionine / Q000032:analysis; D006624:Hippocampus / Q000254:growth & development / Q000378:metabolism*; D006973:Hypertension / Q000139:chemically induced / Q000188:drug therapy / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D011918:Rats, Inbred SHR / Q000378:metabolism*; D011919:Rats, Inbred Strains; D011921:Rats, Inbred WKY; D012965:Sodium Chloride
D000959:Antihypertensive Agents; D010446:Peptide Fragments; D003900:Desoxycorticosterone; D012965:Sodium Chloride; D004744:Enkephalin, Methionine; D004399:Dynorphins; C026770:dynorphin (1-8)