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Developmental differences in dopamine synthesis inhibition by (+/-)-7-OH-DPAT
S L Andersen1, N L Dumont, M H Teicher
1Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, MA 02178, USA.
Naunyn-Schmiedeberg'S Archives of Pharmacology
|August 1, 1997
Summary
Dopamine synthesis regulation by D2-family agonists shows age-dependent changes in rat brain regions. Autoreceptor function, particularly in the prefrontal cortex, decreases with maturation.
Area of Science:
- Neuroscience
- Pharmacology
- Developmental Biology
Background:
- Dopamine synthesis is crucial for brain function and is regulated by autoreceptors.
- The D2-family of dopamine receptors plays a significant role in modulating dopamine release and synthesis.
- Understanding the developmental trajectory of these autoreceptors is key to comprehending neurodevelopmental processes.
Purpose of the Study:
- To investigate the age-dependent modulation of dopamine synthesis by D2-family agonists in specific rat brain regions.
- To characterize the function and sensitivity of dopamine autoreceptors during postnatal development.
- To explore the role of D3 autoreceptor-like activity and its transient nature in the prefrontal cortex.
Main Methods:
- Utilized the gamma-butyrolactone (GBL) autoreceptor model in rats aged 10-40 days.
- Administered the D2-family agonist (+/-)-7-OH-DPAT and the D3/D2 agonist quinpirole.
- Assessed dopamine synthesis inhibition and autoreceptor sensitivity (ID50) in striatum, nucleus accumbens, and prefrontal cortex.
- Performed in vitro studies to examine D3 receptor specificity under low D2 affinity conditions.
Main Results:
- GBL-induced dopamine synthesis increased with age and was inhibited by (+/-)-7-OH-DPAT across all ages studied.
- Autoreceptor sensitivity (ID50) to (+/-)-7-OH-DPAT increased with age, indicating reduced sensitivity in mature rats.
- Prefrontal cortex showed evidence of autoreceptor function from 10-30 days, diminishing by 40 days.
- Inhibition of dopamine synthesis was observed with quinpirole, mirroring (+/-)-7-OH-DPAT effects.
- In vitro studies confirmed potent D3 autoreceptor-like activity.
Conclusions:
- Findings demonstrate D3 autoreceptor-like activity in ascending dopamine pathways.
- A transient, age-dependent autoreceptor function exists in the prefrontal cortex, receding by puberty.
- This study provides insights into the developmental regulation of dopamine systems and autoreceptor sensitivity.