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The aim of this study was to evaluate the immune responses in turbot, Scophthalmus maximus, treated with 1 × 107 cfu/ml attenuated Edwardsiella tarda (0.1 ml/fish) under low density (LD; ∼5.25-5.13 kg/m2, initial to final density), medium density (MD; ∼10.41-13.95 kg/m2), and high density (HD; ∼20.53-30.77 kg/m2) conditions for 8 weeks. The results showed that there was a peak value in the percentage of sIg+ (surface immunoglobulin-positive) cells in blood leucocytes (BL), spleen leucocytes (SL), and pronephros leucocytes (PL) during the sixth week in the HD, which was delayed by week compared with the other groups. The specific immunoglobulin M (IgM) antibody levels increased from the first week in all groups and reached a peak in the fifth week in the LD and MD groups, but in the sixth week in the HD group. The serum cortisol levels were greater in the HD group compared with the other groups in the last 3 or 4 weeks. These results show that stocking turbot at a LD obtained the most effective immunization, and thus we conclude that crowding stress may reduce the ability to deal with immune challenge.

Summary: Neocortical neurons with similar functional properties assemble into spatially coherent circuits, but it remains unclear how inhibitory interneurons are organized. We applied in vivo two-photon functional Ca2+ imaging and whole-cell recording of synaptic currents to record visual responses of cortical neurons and analyzed their spatial arrangements. GABAergic interneurons were clustered in the 3D space of the mouse visual cortex, and excitatory neurons located within the clusters (insiders) had a lower amplitude and sharper orientation tuning of visual responses than outsiders. Inhibitory synaptic currents recorded from the insiders were larger than those of the outsiders. Single, isolated interneurons did not show such a location-tuning/amplitude relationship. The two principal subtypes of interneurons, parvalbumin- and somatostatin-expressing neurons, also formed clusters with only slightly overlapping each other and exhibited a different location-tuning relationship. These findings suggest that GABAergic interneurons and their subgroups form clusters to make their inhibitory function more effective than isolated interneurons. : Ebina et al. find 3D clustering of GABAergic neurons and their principal subtypes, parvalbumin- and somatostatin-expressing neurons. They demonstrate that inhibitory actions on excitatory neurons inside these clusters are stronger than outside, suggesting that GABAergic neurons form clusters in order to make their inhibitory function more effective than in isolated neurons.

With the increasing applications of titanium dioxide nanoparticles (TiO(2) NPs) in industry and daily life, an increasing number of studies showed that TiO(2) NPs may have negative effects on the respiratory or metabolic circle systems of organisms, while very few studies focused on the brain central nervous system (CNS). Synaptic plasticity in hippocampus is believed to be associated with certain high functions of CNS, such as learning and memory. Thus, in this study, we investigated the effects of developmental exposure to TiO(2) NPs on synaptic plasticity in rats' hippocampal dentate gyrus (DG) area using in vivo electrophysiological recordings. The input/output (I/O) functions, paired-pulse reaction (PPR), field excitatory postsynaptic potential, and population spike amplitude were measured. The results showed that the I/O functions, PPR, and long-term potentiation were all attenuated in lactation TiO(2) NPs-exposed offspring rats compared with those in the control group. However, in the pregnancy TiO(2) NPs exposure group, only PPR was attenuated significantly. These findings suggest that developmental exposure to TiO(2) NPs could affect synaptic plasticity in offspring's hippocampal DG area in vivo, which indicates that developmental brains, especially in lactation, are susceptible to TiO(2) NPs exposure. This study reveals the potential toxicity of TiO(2) NPs in CNS. It may give some hints on the security of TiO(2) NPs production and application and shed light on its future toxicological studies.

(−)-Epigallocatechin-3-gallate (EGCG), the main active component of green tea, is commonly known for its beneficial properties at low doses. On the other hand, little is known about the adverse effects of EGCG. Voltage-gated sodium channel (VGSC) is responsible for both initiation and propagation of action potentials of the neurons in the hippocampus and throughout the central nervous system (CNS). In this study, the effects of EGCG on voltage-gated sodium channel currents ( I Na ) were investigated in rat primary cultures of hippocampal CA1 neurons via the conventional whole-cell patch-clamp technique. We found that I Na was not affected by EGCG at the concentration of 0.1 μM, but was completely blocked by EGCG at the concentration of 400 μM and higher, and EGCG reduced the amplitudes of I Na in a concentration-dependent manner in the range of 0.1–400 μM. Furthermore, our results also showed that at the concentration of 100 μM, EGCG was known to have the following performances: (1) it decreased the activation threshold and the voltage at which the maximum I Na current was evoked, caused negative shifts of I Na steady-state activation curve. (2) It enlarged I Na tail-currents. (3) It induced a left shift of the steady-state inactivation. (4) It reduced fraction of available sodium channels. (5) It delayed the activation of I Na in a voltage-dependent manner. (6) It prolonged the time course of the fast inactivation of sodium channels. (7) It accelerated the activity-dependent attenuation of I Na . On the basis of these findings, we propose that EGCG could impair certain physiological functions of VGSCs, which may contribute, directly or indirectly, to EGCG's effects in CNS.

Increasing evidence suggests that lead (Pb) produces impairments partly through oxidative stress. Though many researchers have investigated protective effect of some antioxidant nutrients against Pb toxicity, little information is available about the effect of antioxidants on Pb-induced impairment of synaptic plasticity. Quercetin, a strong antioxidant and radical scavenger, is the representative natural flavonoid molecule abundant in fruits and vegetables. Previous studies have found that quercetin was neuroprotective in many cases. This study was designed to evaluate the effect of quercetin on chronic Pb exposure-induced impairment of synaptic plasticity in adult rat dentate gyrus (DG) area in vivo. The input/output (I/O) functions, paired-pulse reactions (PPR), excitatory postsynaptic potential (EPSP), and population spike (PS) amplitude were measured in the DG area of different groups of rats in response to stimulation applied to the lateral perforant path. The results showed that the depressed I/O, PPR, and long-term potentiation (LTP) of Pb-exposed group were significantly increased by quercetin treatment. In addition, hippocampal Pb concentration was partially reduced after quercetin treatment. These findings suggest that quercetin treatment could relieve chronic Pb exposure-induced impairment of synaptic plasticity and might be a potential therapeutic intervention to cure cognitive deficits induced by Pb.