Study wrapper · #679
Antidepressant-like and antistress effects of the ACTH(4-10) synthetic analogs Semax and Melanotan II on male rats in a model of chronic unpredictable stress.
Editor's note
In a chronic-unpredictable-stress rat model of depression, low-dose Semax and Melanotan II were associated with reduced or attenuated stress-induced anhedonia (loss of sucrose preference), less suppression of body-weight gain, reduced adrenal hypertrophy and preserved hippocampal BDNF, though neither peptide changed immobility in the forced-swim test. This is a preclinical behavioral-pharmacology study in male rats only; the mixed endpoint results (positive on anhedonia, null on forced swim) argue for cautious interpretation. It adds a stress and mood strand to Semax's rodent literature and offers a plausible BDNF-linked mechanism, but says nothing about human mood outcomes. These are preclinical findings; human data are needed before clinical conclusions can be drawn.
Plain-language abstract
Depression is linked to long-term stress and an overactive stress-hormone system. This study tested whether two ACTH-related peptides, Semax and Melanotan II, could ease depression-like behavior in rats exposed to weeks of unpredictable stress. Male rats got daily low-dose injections of one peptide or salt water. Chronically stressed rats normally lose interest in sugar water (a sign of reduced pleasure), gain less weight, develop enlarged adrenal glands, and show lower levels of a brain growth factor called BDNF. Both peptides reduced or reversed several of these stress effects and helped preserve BDNF. However, in a separate 'forced swim' test, neither peptide changed the rats' behavior. The authors suggest these peptides may have promise for stress-related conditions. Because this was done in male rats with mixed results, it shows a possible mechanism rather than a benefit in people, and no adverse effects were reported.