Repeated amphetamine evokes biphasic alterations in the tyrosine hydroxylase mRNA level in the rat adrenal medulla: an in situ hybridization study.
In the present study we estimated the effects of single and repeated administration of d-amphetamine (5 mg/kg, i.p., twice a day for 14 days) on tyrosine hydroxylase (TH) mRNA levels in the rat adrenal medulla. In situ hybridization experiments, conducted using a [35S]d-ATP-labelled deoxyoligonucleotide probe and a densitometric analysis of autoradiograms, showed that repeated d-amphetamine moderately increased the TH mRNA level (by ca. 24%) in the adrenal medulla at 2 h after the last injection. In contrast, after 48 h the TH mRNA level was decreased (by ca. 21%). No significant changes in the TH mRNA level in the adrenal medulla were found following single administration of d-amphetamine. These results suggest that repeated d-amphetamine administration leads to biphasic changes in the adrenal TH biosynthesis, which may reflect an adaptive response to chronic drug treatment.
Jaworska
L
L
Department of Endocrinology, Polish Academy of Sciences, Kraków.
Budziszewska
B
B
Lasoń
W
W
D000313:Adrenal Medulla / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D001345:Autoradiography; D003913:Dextroamphetamine / Q000494:pharmacology*; D017403:In Situ Hybridization; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis*
D012333:RNA, Messenger; D014446:Tyrosine 3-Monooxygenase; D003913:Dextroamphetamine