Characteristics of [3H]CGP12177 binding sites at beta 2- and beta 3-adrenoceptors in the guinea pig taenia caecum

Stoichiometric analysis of oligomerization of membrane proteins on living cells using coiled-coil labeling and spectral imaging

Many membrane proteins are proposed to work as oligomers; however, the conclusion is sometimes controversial, as for β2-adorenergic receptor (β2AR), which is one of the best-studied family A G-protein-coupled receptors. This is due to the lack of methods for easy and precise detection of the oligomeric state of membrane proteins on living cells. Here, we show that a combination of the coiled-coil tag-probe labeling method and spectral imaging enable a stoichiometric analysis of the oligomeric state of membrane proteins on living cells using monomeric, dimeric, and tetrameric standard membrane proteins. Using this method, we found that β2ARs do not form constitutive homooligomers, while they exhibit their functions such as the cyclic adenosine 5'-monophosphate (cAMP) signaling and internalization upon agonist stimulation.

Endogenous CART peptide regulates mu opioid and serotonin 5-HT(2A) receptors

Previous experiments conducted in this laboratory showed that intracerebroventricular (i.c.v.) administration of IgG antibodies directed against selected neuropeptides changed the density of CNS receptors, suggesting that neuropeptides in the cerebrospinal fluid can perform a regulatory role. To further test this hypothesis, we administered anti-CART peptide (the peptide product of cocaine amphetamine related transcript) IgG to rats via the i.c.v. route, and measured the density of opioid mu and delta receptors, beta-adrenergic and alpha(2)-adrenergic receptors and serotonin 5-HT(2A) receptors using ligand binding methods. We also used Western blots to determine the expression level of the mu, delta and 5-HT(2A) receptors. The results demonstrated that anti-CART peptide IgG up-regulates mu and 5-HT(2A) receptor in the hippocampus and caudate We conclude that CART peptides in the cerebrospinal fluid may exert regulatory effects in the brain.

Endogenous corticotropin releasing factor regulates adrenergic and opioid receptors

Previous work from this laboratory demonstrated that intracerebroventricular (i.c.v.) administration of IgG antibodies directed against selected neuropeptides changed the density of opioid receptors, suggesting that neuropeptides in the CNS can perform a regulatory role. To further test this hypothesis, we administered anticorticotropin (CRF) IgG to rats via the i.c.v. route and measured the density of opioid mu and delta receptors and also beta- and alpha(2)-adrenergic receptors. The results demonstrated that anti-CRF IgG upregulates mu and beta-adrenergic receptors. We conclude that CRF in the cerebrospinal fluid may exert regulatory effects throughout the brain.