Effect of naloxone-precipitated morphine withdrawal on CRH and vasopressin mRNA expression in the rat hypothalamic paraventricular nucleus.
Morphine withdrawal is characterized by an increase in the hypothalamus-pituitary-adrenocortical (HPA) axis activity. Here, by means of in situ hybridization, the changes in CRH and vasopressin (AVP) mRNAs have been analysed within the rat hypothalamic paraventricular nucleus (PVN) during morphine dependence and after naloxone-precipitated morphine withdrawal. CRH and AVP mRNA expression were analysed 30 min following administration of saline or naloxone to control groups and to morphine dependent rats. The data for in situ hybridization analysis of PVN neurons show that there were no changes in the total size of labelled area for CRH or AVP mRNA during morphine withdrawal, indicating that dependence on morphine does not involve alterations in the number of neurons expressing CRH or AVP mRNA. However, levels of mRNA encoding for CRH were decreased in the PVN during morphine dependence and withdrawal. By contrast, injection of saline or naloxone to morphine dependent rats did not affect the intensity of AVM mRNA expression. All these findings are discussed in term of cellular events that couple morphine dependence-increased HPA axis activity with changes in gene expression in selective neurons of the PVN.
Milanés
M V
MV
Department of Pharmacology, University School of Medicine, Murcia, Spain. milanes@um.es
Laorden
M L
ML
Angel
E
E
Tankosic
P
P
Burlet
A
A
D000324:Adrenocorticotropic Hormone / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000502:physiology; D017403:In Situ Hybridization; D008297:Male; D009021:Morphine Dependence / Q000503:physiopathology*; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism*; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*; D014667:Vasopressins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
D009292:Narcotic Antagonists; D012333:RNA, Messenger; D014667:Vasopressins; D009270:Naloxone; D000324:Adrenocorticotropic Hormone