Two vasopressin-like peptides in the pig testis?

Area of Science:

• Endocrinology
• Reproductive Biology
• Molecular Endocrinology

Background:

• Vasopressin (VP)-like immunoreactivity (IR) is present in mammalian testes.
• Evidence suggests that rat testicular VP-like IR may not be authentic arginine vasopressin (AVP), hinting at a second AVP-like peptide.

Purpose of the Study:

• To investigate the presence and nature of VP-like peptides in pig testes, which produce lysine vasopressin (LVP).
• To determine if pig testes contain both LVP- and AVP-like peptides.

Main Methods:

• High-performance liquid chromatography (HPLC) was used to analyze pig testis extracts.
• Specific antisera recognizing LVP and AVP were employed to identify VP-like peptides.
• Neurophysin affinity chromatography was performed on the VP-like peptides.
• Oxidation with performic acid followed by HPLC was used to characterize the peptides.

Main Results:

• Two distinct peaks of VP-like immunoreactivity were detected in pig testis extracts via HPLC.
• One peak co-eluted with authentic LVP and was recognized by LVP-specific antisera.
• The second peak co-eluted with authentic AVP and was recognized by AVP-specific antisera.
• Both peptides bound to a neurophysin affinity column and behaved similarly to authentic hormones upon oxidation.

Conclusions:

• Pig testes contain both LVP-like and AVP-like peptides.
• The presence of these two distinct peptides suggests the involvement of more than one gene in VP-like peptide production in the pig testis.
• This finding may offer an explanation for previously observed anomalies in VP-like immunoreactivity in other species.