Vasopressin antisense peptide interactions with the V1 receptor

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• The molecular recognition hypothesis proposes that peptide ligands and their receptor binding sites are encoded by complementary nucleotide sequences.
• Arginine vasopressin (AVP) is a peptide hormone that plays a role in regulating blood pressure and water balance.
• The V1 receptor is one of the primary receptors for AVP.

Purpose of the Study:

• To test the molecular recognition hypothesis for AVP and its V1 receptor.
• To determine if a complementary peptide to AVP (PVA) can inhibit AVP binding to V1 receptors.
• To investigate the in vivo effects of PVA on AVP-mediated physiological responses.

Main Methods:

• Radioligand binding assays using [125I] [d(CH2)5,Sar7]AVP and [3H]AVP on rat liver plasma membranes.
• Testing inhibition of binding by known V1 receptor ligands and the AVP complementary peptide (PVA).
• Immunoreactivity testing of anti-PVA antibodies with liver membrane proteins.
• In vivo rat blood pressure bioassay to assess the AVP pressor effect suppression by PVA.

Main Results:

• Peptides known to bind V1 receptors inhibited [125I] [d(CH2)5,Sar7]AVP and [3H]AVP binding.
• The AVP complementary peptide (PVA) did not inhibit the binding of radioligands to V1 receptors.
• Rabbit anti-PVA antibodies showed no immunoreactivity with rat liver membrane proteins.
• PVA did not suppress the AVP pressor effect in vivo.

Conclusions:

• The study's findings do not support the molecular recognition hypothesis for AVP and its V1 receptor.
• The V1 receptor binding site does not appear to be encoded by the antisense DNA strand to AVP.
• These results suggest an alternative mechanism for molecular recognition in the AVP system.