Abstract: Peptides characterized by: a) a sequence selected from the group consisting of the sequence SEQ ID NO: 2, and the derived variants having at least 70% identity or 80% similarity with the entire sequence SEQ ID NO: 2, b) a three-finger structure including eight cysteine residues linked by four disulfide bridges, respectively between the first and the third cysteine, the second and the fourth cysteine, the fifth and the sixth cysteine, and the seventh and the eighth cysteine, and c) an activity of an allosteric antagonist selective for the alpha 1a adrenergic receptor, and therapeutic and pharmacological uses thereof.