Abstract
To quantify changes in neuronal nAChR binding in vivo, quantitative dynamic SPECT studies were performed with 5-[123I]-iodo-A-85380 in baboons pre and post chronic treatment with (-)-nicotine or saline control. Infusion of (-)-nicotine at a dose of 2.0 mg/kg/24h for 14 days resulted in plasma (-)-nicotine levels of 27.3 ng/mL. This is equivalent to that found in an average human smoker (20 cigarettes a day). In the baboon brain the regional distribution of 5-[123I]-iodo-A-85380 was consistent with the known densities of nAChRs (thalamus > frontal cortex > cerebellum). Changes in nAChR binding were estimated from the volume of distribution (Vd) and binding potential (BP) derived from 3-compartment model fits. In the (-)-nicotine treated animal Vd was significantly increased in the thalamus (52%) and cerebellum (50%) seven days post cessation of (-)-nicotine treatment, suggesting upregulation of nAChRs. The observed 33% increase in the frontal cortex failed to reach significance. A significant increase in BP was seen in the thalamus. In the saline control animal no changes were observed in Vd or BP under any experimental conditions. In this preliminary study, we have demonstrated for the first time in vivo upregulation of neuronal nAChR binding following chronic (-)-nicotine treatment.
Original language | English |
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Pages (from-to) | 165-175 |
Number of pages | 11 |
Journal | Nuclear Medicine and Biology |
Volume | 28 |
Issue number | 2 |
DOIs | |
State | Published - 2001 |
Keywords
- (-)-Nicotine
- 5-[I]-iodo-A-85380
- NAChR upregulation
- Quantitative dynamic SPECT