Contrasting effects of repeated treatment vs. withdrawal of methamphetamine on tyrosine hydroxylase messenger RNA levels in the ventral tegmental area and substantia nigra zona compacta of the rat brain.
We have assessed the effect of repeated treatment with methamphetamine (METH) on the abundance of the messenger ribonucleic acid molecules encoding the enzyme tyrosine hydroxylase (TH) and preprocholecystokinin (PPCCK) in the substantia nigra zona compacta (SNc) and the ventral tegmental area (VTA) by in situ hybridization histochemistry. Rats were injected twice daily with METH (4 mg/kg of body weight) for 6 consecutive days and sacrificed either 5 h or 15 days after the last injection. TH mRNA in the VTA was unaffected by repeated METH treatment but was decreased 25% relative to controls in the SNc. Concurrent administration of METH and MK-801 decreased TH mRNA levels in the SNc to 47% relative to controls. In contrast, TH mRNA levels were found increased in the VTA (42%) but not SNc 15 days post-METH treatment. Coadministration of MK-801 with METH prevented the increase in TH mRNA in the VTA. PPCCK mRNA levels were not significantly affected by METH treatment in VTA or SNc either 5 h or 15 days posttreatment. The results demonstrate that exposure to repeated methamphetamine elicits changes of TH mRNA levels in the VTA that become manifest 2 weeks after withdrawal from this psychostimulant drug.
Zhang
Y
Y
Department of Biological Sciences, Hunter College of the City University of New York, New York 10021, USA.
Angulo
J A
JA
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D002766:Cholecystokinin / Q000096:biosynthesis; D018765:Dopamine Uptake Inhibitors / Q000009:adverse effects / Q000494:pharmacology*; D017403:In Situ Hybridization; D008297:Male; D008694:Methamphetamine / Q000009:adverse effects / Q000494:pharmacology*; D015345:Oligonucleotide Probes; D011498:Protein Precursors / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013375:Substance Withdrawal Syndrome / Q000378:metabolism*; D013378:Substantia Nigra / Q000187:drug effects / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis*; D017557:Ventral Tegmental Area / Q000187:drug effects / Q000378:metabolism*
D018765:Dopamine Uptake Inhibitors; D015345:Oligonucleotide Probes; D011498:Protein Precursors; D012333:RNA, Messenger; D008694:Methamphetamine; C042082:preprocholecystokinin; D002766:Cholecystokinin; D014446:Tyrosine 3-Monooxygenase