MIF-1 TFA

MIF-1 TFA (Melanostatin TFA) is an endogenous brain peptide that acts as a potent allosteric modulator of dopamine receptors. It inhibits melanin production and blocks the activation of opioid receptors, thereby modulating morphine-induced analgesia and stress-induced analgesia (SIA). MIF-1 TFA can directly cross the blood-brain barrier (BBB) to enter the central nervous system from the bloodstream.

Method: Primary cultured melanotrophs from the frog pituitary (Rana ridibunda) were studied using the whole-cell patch-clamp technique. MIF-1 TFA (1 μM) was applied by pressure ejection (0.5–10 s). Changes in membrane potential, membrane resistance, whole-cell current, as well as voltage-activated potassium, sodium, and calcium currents were recorded.

Results: MIF-1 TFA (1 μM) induced a reversible hyperpolarization (2–24 mV) and inhibited spontaneous firing, accompanied by a decrease in membrane resistance. It induced an outward potassium current (reversal potential approximately –100 mV), increased voltage-activated potassium currents (by approximately 30%), and reduced fast sodium currents (by approximately 30%). MIF-1 TFA also inhibited high voltage-activated N-type and L-type calcium currents (by 50–70%). Pretreatment with pertussis toxin (PTX) blocked its inhibitory effect on calcium currents [1].

Method: Male Wistar rats (180–200 g) received intraperitoneal injections of MIF-1 (1 mg/kg). The effect on morphine-induced (1 mg/kg i.p.) acute analgesia was evaluated using the paw-pressure (PP) and tail-flick (TF) tests.
Result: MIF-1 (1 mg/kg i.p.) significantly reduced the analgesic effect induced by morphine [2].