Abstract

Maternal separation (MS) is a model to induce permanent alternations in the central nervous system (CNS) and is associated with increased levels of anxiety and cognitive deficiencies. Since methyl donor choline (Ch) has been shown to play a significant role in learning and memory and enhance synaptic plasticity, the authors hypothesized that Ch may attenuate MS-induced impairments in synaptic plasticity and cognitive performance. Rat pups underwent an MS protocol for 180 min/day from postnatal day (PND) 1 to 21. Ch was administered subcutaneously (100 mg/kg, 21 days) to the choline chloride and MS + choline chloride groups from PND 29 to 49. Anxiety-like behaviour, recognition memory, and spatial and passive avoidance learning and memory were measured in the adolescent rats. In addition, evoked field excitatory postsynaptic potentials (fEPSP) were recorded from the CA1 region of the hippocampus. MS induced higher anxiety-like behaviour in the animals. It also impaired learning and memory. However, MS had no effect on locomotor activity. Subcutaneous administration of Ch attenuated MS-induced cognitive deficits and enhanced the learning and memory of MS rats. Ch also decreased anxiety-like behaviour in the open-field test. The present results showed that long-term potentiation (LTP) was induced in all groups except MS and MS + saline animals. However, Ch injection induced LTP and had maintenance in MS + choline chloride, but it was not statistically significant compared with the MS group. In summary, the present findings indicate that MS can interfere with normal animal's cognition and subcutaneous of Ch may be considered an appropriate therapeutic strategy for promoting cognitive dysfunctions in MS animals.