title: [Effect of AT₁ receptor on changes of tyrosine hydroxylase-immunoreactivity in rostral ventrolateral medulla induced by brain cholinergic stimuli in rats].
abstract: OBJECTIVE
  To investigate the effect of AT₁ receptor on the changes of tyrosine hydroxylase-immunoreactivity (TH-IR) in rostral ventrolateral medulla (RVLM) induced by brain cholinergic stimuli in rats.
  
  
  METHODS
  Male SD rats were randomly divided into 4 groups: NS + CBC group, Los + CBC group, Los + NS group and NS + NS group. AT₁ was blocked by pretreatment of 20 μg losartan in Los + CBC and Los + NS groups; intracerebroventricular injection of 0.5 μg carbachol was used for cholinergic stimuli in NS + CBC and Los + CBC groups; normal saline (NS) was used for control. The output amount of natrium in kidney, glomerular filtration rate (GFR) and renal plasma flow (PRF) were observed. The changes of TH-IR in the RVLM were observed by immunohistochemistry.
  
  
  RESULTS
  In NS + CBC group carbachol induced potent natriuresis, after pretreatment of losartan the natriuretic effect was partially inhibited in Los + CBC group. Both the number and optical density of TH-IR positive neurons in NS + CBC group were markedly increased than those in NS + NS group (P < 0.05); while those in Los + CBC group were significantly lower than those in NS+CBC group (P < 0.05). Intracerebroventricular injection of carbachol and losartan had no effect on GFR and RPF(P > 0.05).
  
  
  CONCLUSIONS
  The results suggest that cholinergic stimuli can induce potent natriuresis and increase the activity of adrenergic neurons in the RVLM; the above effects can be down regulated by blockade of brain AT₁ receptor.
authors.affiliation: Department of Physiology, Jiaxing University, School of Medicine, Jiaxing 314001, China. wmwmwmtom@yahoo.com.cn
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Qi-ying
authors.initials: QY
authors.lastname: Yao
authors.forename: Man-li
authors.initials: ML
authors.lastname: Xia
authors.forename: Xin-mei
authors.initials: XM
authors.lastname: Zhou
authors.forename: Chun-ling
authors.initials: CL
authors.lastname: Jiang
mesh_terms: D000818:Animals; D002217:Carbachol / Q000008:administration & dosage / Q000494:pharmacology; D004336:Drug Antagonism; D005919:Glomerular Filtration Rate / Q000187:drug effects; D019808:Losartan / Q000494:pharmacology; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000378:metabolism*; D009318:Natriuresis / Q000187:drug effects; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1 / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D044140:Receptor, Angiotensin, Type 1; D002217:Carbachol; D014446:Tyrosine 3-Monooxygenase; D019808:Losartan