Although the molecular mechanism is not clear, the clinically tested drug ketamine has rapid antidepressant action that does not require the multiple weeks of treatment needed for other antidepressant drugs to have an effect. We showed that ketamine potentiated Schaffer collateral–CA1 cell excitatory synaptic transmission in hippocampal slice preparations from rodents and enhanced the phosphorylation of the GluA1 subunit on Ser845 of the AMPA-type glutamate receptor in the hippocampal area CA1. These effects persisted when γ-aminobutyric acid (GABA) receptors were pharmacologically blocked. Ketamine reduced behavioral despair in wild-type mice but had no effect in GluA1 S845A knock-in mutant mice. Presynaptic (CA3 pyramidal cell), but not postsynaptic (CA1 pyramidal cell), deletion of N-methyl-d-aspartate (NMDA)–type glutamate receptors eliminated the ketamine-induced enhancement of excitatory synaptic transmission in hippocampal slices and the antidepressant actions of ketamine in mice. The synaptic and behavioral actions of ketamine were completely occluded by inhibition or deletion of the hyperpolarization-activated cyclic nucleotide–gated channel 1 (HCN1). Our results implicate presynaptic NMDA receptor inhibition followed by reduced activity of presynaptic HCN1 channels, which would result in an increase in glutamate release and postsynaptic glutamate receptor activity, as a mechanism of ketamine action. These data provide a mechanism for changes in synaptic activity that could explain the fast-acting antidepressant effects of this drug.

Sex differences in spatial memory have long been observed in humans, non-human primates and rodents, but the underlying cellular and molecular mechanisms responsible for these differences remain obscure. In the present study we found that adolescent male rats outperformed female rats in 7 d and 28 d retention probes, but not in learning trials and immediate probes, in the Morris water maze task. Male rats also had larger long-term potentiation (LTP) at hippocampal temproammonic-CA1 (TA-CA1) synapses, which have been implicated to play a key role in place field and memory consolidation, when protocols designed to elicit late-stage LTP (LLTP) were used. Interestingly, the ratio of evoked AMPA/NMDA currents was found to be smaller at TA-CA1 synapses in male rats compared to female rats. Protein biotinylation experiments showed that male rats expressed more surface GluN1 receptors in hippocampal CA1 stratum lacunosum-moleculare (SLM) than female rats, although GluA1 expression was also slightly higher in male rats. Taken together, our results suggest that differences in the expression of AMPA and NMDA receptors may affect LTP expression at TA-CA1 synapses in adolescent male and female rats, and thus possibly contribute to the observed sex difference in spatial memory.

Wilson's disease (WD) is an autosomal recessive inheritance disorder of copper metabolism due to mutations in the ATP7B gene. The distribution of ATP7B gene mutations is diverse in different population. This study aimed to examine the genotypes of the ATP7B mutant alleles in WD patients from Southern China. Genomic DNA was extracted from 103 WD patients and 60 healthy patients. Mutations were screened and detected by DNA sequencing. A total of 51 different ATP7B mutations were identified in WD patients, including six homozygous, 51 compound heterozygous, and 39 single heterozygotes. Three mutations were found to be novel, including one missense mutation (c.2549C>T) and two frameshift mutations (c.3851_3876del and c.1057delC). The most frequent mutations are Arg778Leu (18.93%), Ile1148Thr (8.74%), and Pro992Leu (4.37%). Different from the published results of early studies, Ile1148Thr was found to be the second common mutation in our cohort. The highest mutation detection rate was on exon 8 (43.69%), followed by exon 16 (24.27%), and exon 12 (17.48%). The total mutation detection rate on exon 8, 12, and 16 was 85.44%. No ATP7B gene mutation was found in healthy patients. In conclusion, we identified three novel mutations and Ile1148Thr as another hotspot mutation in WD patients from Southern China. Most of the mutations can be detected by screening exon 8, 12, and 16. Our research has further enriched the mutation spectrum of the ATP7B gene in Chinese and may help to develop genetic screening strategies of WD.

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