G(olf) in the basal ganglia.

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Guanine nucleotide-binding (G) proteins, specifically G(s), are crucial for mediating signals from neurotransmitter and hormone receptors to adenylyl cyclase.
• Dopamine D1 receptors in the basal ganglia are known to stimulate adenylyl cyclase, traditionally attributed to G(s).

Purpose of the Study:

• To investigate the specific G proteins involved in adenylyl cyclase stimulation in the rat basal ganglia.
• To determine the identity and abundance of stimulatory G proteins in the striatum and related basal ganglia structures.

Main Methods:

• Immunohistochemistry and immunoblotting to detect G protein levels.
• Cholera toxin-dependent ADP ribosylation to assess G protein activity.
• In situ hybridization and Northern blot analysis to quantify G protein mRNA expression.

Main Results:

• Rat basal ganglia exhibit high levels of a G(salpha)-like protein distinct from G(s) found in other brain regions.
• Striatum shows remarkably low messenger RNA (mRNA) levels for G(salpha).
• High expression of G-alpha-olf (G(olf)) mRNA was discovered in the striatum, nucleus accumbens, and olfactory tubercle, with G(olf) transcripts being approximately 10-fold more abundant than G(salpha) transcripts in the striatum.

Conclusions:

• G-alpha-olf (G(olf)) is not exclusive to olfactory neurons and is the predominant stimulatory G protein in the basal ganglia.
• G(olf) likely plays a key role in coupling D1 dopamine receptors to adenylyl cyclase in the basal ganglia.