Melanocyte-Stimulating Hormone Release-Inhibiting Factor (trifluoroacetate salt)

Melanocyte-stimulating hormone release-inhibiting factor (MSH-R-IF) is a pothalamic tripeptide that binds to rat striatum (K_d = 4.69 nM) and has diverse biological activities.^1,2,3,4 In vivo, MSH-R-IF (0.1 mg/kg) decreases immobility of mice in the forced swim test, indicating antidepressant-like activity.² MSH-R-IF (20 mg/kg) increases striatal concentration of dopamine and the dopamine metabolites DOPAC, 3-methoxy tyramine , and homovanillic acid (HVA) in a mouse model of Parkinson's disease induced by MPTP.³ It decreases vacuous chewing movements induced by haloperidol in a rat model of tardive dyskinesia when administered at a dose of 2 mg/kg.⁴ MSH-R-IF also has anti-opiate effects, reversing analgesia induced by morphine and an enkephalin in mice in a radiant heat tail-flick assay.¹