Since vasopressin has been shown to be critical for adaptation of the hypothalamo-pituitary-adrenal axis during stress through its ability to potentiate the stimulatory effect of CRF, it has been hypothesized that this peptide may provide a good opportunity for pharmacological treatment of stress-related disorders. The availability of the first orally active nonpeptide V1b receptor antagonist, SSR149415, opened a new era for examining the role of vasopressin in animal models of anxiety and depression. In rats, SSR149415 blocked several endocrine (i.e. ACTH release), neurochemical (i.e. noradrenaline release) and autonomic (i.e. hyperthermia) responses following various stress exposures. Moreover, the drug was able to attenuate some but not all stress-related behaviors in rodents. While the antidepressant-like activity of the compound was comparable to that of reference antidepressants, the overall profile displayed in anxiety tests was different from that of classical anxiolytics, such as benzodiazepines. These latter were highly effective and reliably produced robust effects in most anxiety tests, while SSR149415 showed clear-cut effects only in particularly stressful situations. Experiments with mice or hamsters indicated that V1b receptor blockade is associated with reduced aggressiveness, suggesting that SSR149415 could prove useful for treating aggressive behavior. It is important to note that SSR149415 is devoid of adverse effects on motor functions or cognitive processes, and it did not produce tolerance to its anxiolytic- or antidepressant-like activity. Altogether, these findings suggest that V1b receptor antagonists represent a promising alternative to agents currently used for the treatment of depression and some forms of anxiety disorders.
Keywords: antidepressant, anxiety, anxiolytic, depression, ssr, stress, vb receptor, vasopressin
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