Changes of dopamine transporter function in striatum during acute morphine addiction and its abstinence in rhesus monkey.
BACKGROUND
Although dopamine transporter (DAT) is essential for addiction, the effect of additive drugs on DAT function is still controversial, especially for opiates. We investigated the functional changes of dopamine transporter in striatum of rhesus monkeys during acute morphine injection and its abstinence.


METHODS
Four rhesus monkeys, 6 to 9 years old, two male and two female, were examined for 12 days. Single photon emission computed tomography (SPECT) was performed with (99)T(cm)-TRODAT-1 as the radiopharmaceutical dopamine transporter agent during different stages of acute morphine injection and its abstinence. The ratios of SPECT signal between striatum and cerebellum (ST/CB) were calculated.


RESULTS
The ST/CB ratio declined significantly on the first day of morphine injection and continued declining with more morphine injections. After abstinence, the ratio increased with time, but was still significantly lower on the 5th day of abstinence than the normal level.


CONCLUSIONS
In rhesus monkey, acute morphine injection has both rapid and lasting effects on DAT by downregulating its function. The decline was partially reversible following morphine abstinence. The results suggest that striatum is one effective target of morphine and that the DAT function in striatum is one indicator for morphine addiction.
Xiao
Zhuang-wei
ZW
Department of Radiology, First Affiliated Hospital of Shantou University Medical College, Shantou 515041, China. xiaozw@vip.163.com
Cao
Chu-yu
CY
Wang
Zhao-xin
ZX
Li
Jun-xiong
JX
Liao
Hai-yong
HY
Zhang
Xue-xin
XX
D000208:Acute Disease; D000818:Animals; D002531:Cerebellum / Q000378:metabolism; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism; D050483:Dopamine Plasma Membrane Transport Proteins / Q000032:analysis / Q000502:physiology*; D005260:Female; D008253:Macaca mulatta; D008297:Male; D009021:Morphine Dependence / Q000503:physiopathology*; D015609:Organotechnetium Compounds; D015899:Tomography, Emission-Computed, Single-Photon; D014326:Tropanes
D050483:Dopamine Plasma Membrane Transport Proteins; D015609:Organotechnetium Compounds; D014326:Tropanes; C104196:technetium Tc 99m TRODAT-1