Effects of melanostatine (MIF-1) on focal potentials in slices of rat brain cortex

The effects of tripeptide melanostatine (Melano-Inhibitory Factor — MIF-1) in concentrations 10 −7–10 −5M on parameters of focal potentials (FPs) were studied in slices of rat oflactory and parietal cortex. The addition of MIF-1 to perfusion fluid caused in olfactory cortex the primary depression of FP amplitudes evoked by stimulation of the lateral olfactory tract (LOT); this depression was replaced by restoration and prolonged (30–40 min) enhancement of FP amplitudes and by appearance of additional FP components, such as disynaptic EPSPs and IPSPs. In parietal cortex slices MIF-1 caused the elevation of FP amplitudes evoked by stimulating adjoining points. The repetitive perfusion of slices with MIF-1 potentiated the peptide effect on the increase of FP amplitudes. During excitatory period MIF-1 influenced specifically the functional plasticity in olfactory cortex, having facilitated the induction and sustaining of post-tetanic potentiation (PTP). Data observed support the idea of the activitatory influence of MIF-1 on the CNS at the cellular level, which is likely to lie in the ground of antidepressant properties of this peptide.