PMID- 12361696
OWN - NLM
STAT- MEDLINE
DCOM- 20030507
LR  - 20190922
IS  - 1043-6618 (Print)
IS  - 1043-6618 (Linking)
VI  - 46
IP  - 4
DP  - 2002 Oct
TI  - The role of alpha-adrenoceptors in the amnestic effect of intracerebroventricular 
      dexamethasone.
PG  - 339-44
AB  - Corticosteroids exert dual enhancing or impairing effects on cognitive functions. 
      While their memory-enhancing effects have been well investigated, the mechanisms 
      involved in their amnestic effects are not completely understood. Thus, we 
      examined the role of alpha-adrenoceptors on dexamethasone-induced amnesia using 
      step-through passive avoidance test in rat. Intracerebroventricular (i.c.v.) 
      injection of dexamethasone (5 and 10 microg per rat) decreased the retention 
      latencies. Likewise, intraperitoneal administration of alpha(2)-adrenoceptor 
      agonist clonidine (0.1-0.3 mg kg(-1)) but not alpha(2)-adrenoceptor antagonist 
      yohimbine (0.5-2 mg kg(-1)) decreased the retention latency. Yohimbine 
      pre-treatment decreased the amnestic effects of dexamethasone or dexamethasone 
      plus clonidine. On the other hand, intraperitoneal administration of 
      alpha(1)-adrenoceptor agonist phenylephrine (0.5-2 mg kg(-1)) per se increased, 
      while prazosin at 2 mg kg(-1) decreased the retention latency. Administration of 
      phenylephrine before dexamethasone completely reversed the amnestic effect of the 
      latter, while prozosin did not affect dexamethasone-induced amnesia. These data 
      suggest that dexamethasone may induce its amnestic effect through activation of 
      alpha(2)-adrenoceptors, leading to decreased alpha(1)-adrenergic activity.
FAU - Zarrindast, Mohammad Reza
AU  - Zarrindast MR
AD  - Department of Pharmacology, School of Medicine, Tehran University of Medical 
      Sciences, P.O. Box 13145-784, Tehran, Iran. zarinmr@ams.ac.ir
FAU - Hadi, Mohsen
AU  - Hadi M
FAU - Homayoun, Houman
AU  - Homayoun H
FAU - Postami, Parvin
AU  - Postami P
FAU - Shafaghi, Bijan
AU  - Shafaghi B
FAU - Khavandgar, Simin
AU  - Khavandgar S
LA  - eng
PT  - Journal Article
PL  - Netherlands
TA  - Pharmacol Res
JT  - Pharmacological research
JID - 8907422
RN  - 0 (Adrenergic alpha-Agonists)
RN  - 0 (Adrenergic alpha-Antagonists)
RN  - 0 (Receptors, Adrenergic, alpha)
RN  - 1WS297W6MV (Phenylephrine)
RN  - 2Y49VWD90Q (Yohimbine)
RN  - 7S5I7G3JQL (Dexamethasone)
RN  - MN3L5RMN02 (Clonidine)
RN  - XM03YJ541D (Prazosin)
SB  - IM
MH  - Adrenergic alpha-Agonists/pharmacology
MH  - Adrenergic alpha-Antagonists/pharmacology
MH  - Amnesia/*chemically induced
MH  - Animals
MH  - Avoidance Learning/drug effects
MH  - Clonidine/pharmacology
MH  - Dexamethasone/antagonists & inhibitors/*toxicity
MH  - Dose-Response Relationship, Drug
MH  - Injections, Intraventricular
MH  - Male
MH  - Memory/drug effects
MH  - Phenylephrine/pharmacology
MH  - Prazosin/pharmacology
MH  - Rats
MH  - Rats, Wistar
MH  - Receptors, Adrenergic, alpha/drug effects/*physiology
MH  - Yohimbine/pharmacology
EDAT- 2002/10/04 04:00
MHDA- 2003/05/08 05:00
CRDT- 2002/10/04 04:00
PHST- 2002/10/04 04:00 [pubmed]
PHST- 2003/05/08 05:00 [medline]
PHST- 2002/10/04 04:00 [entrez]
AID - S1043661802001482 [pii]
AID - 10.1016/s1043661802001482 [doi]
PST - ppublish
SO  - Pharmacol Res. 2002 Oct;46(4):339-44. doi: 10.1016/s1043661802001482.