Long-term potentiation (LTP) can be induced by various tetanic parameters in the mammalian visual cortex. However, little researches have been done on the relationship between the expression of the long-lasting LTP (late phase LTP or L-LTP) lasting more than 3 h and the tetanic parameters. In the present study, the effects of 2 Hz and 100 Hz tetanic parameters on L-LTP of the field potentials were recorded from the layer II/III of the rat visual cortical slices in response to stimulation of the layer IV. As a result, tetanic parameters that had more than 300 pulses reliably induced L-LTP in the postnatal day 15-21 rats. Obviously different L-LTP expressions were induced by 2 Hz and 100 Hz tetani. There was no difference in L-LTP expression induced by the parameters with the same frequency and different total pulses. These data suggest that L-LTPs induced by different frequency parameters may have different induction and maintenance mechanisms; L-LTPs induced by the parameters with the same frequency may have the same mechanisms.
Animals ; Electric Stimulation ; methods ; Long-Term Potentiation ; physiology ; Male ; Rats ; Rats, Sprague-Dawley ; Synaptic Transmission ; physiology ; Visual Cortex ; physiology

Previous reports suggested that a low-frequency stimulus (LFS) of 1~2 Hz (600~900 pulses) induced a homosynaptic long-term depression (LTD) of synaptic efficacy in the hippocampal CA1 area of young rats (< 4-week old). However, these stimulation protocols often failed to induce LTD in the adult CA1 hippocampus. In the present study, we examined the effects of two novel tetanus patterns on LTD induction in adult rat hippocampal slices. We determined that these novel stimulation protocols induced LTD in the adult hippocampus, and that the characteristics of induced LTD were parameter-specific, including latency (period from the end of tetanus to a beginning of LTD) and the amplitude of LTD. These results suggest that LFS with certain patterns can induce LTD in the CA1 area of adult rat hippocampal slices, and that the multi-trains of 2-Hz protocol provided more effective response than the 5-Hz protocol.
Animals ; CA1 Region, Hippocampal ; physiology ; Electric Stimulation ; In Vitro Techniques ; Long-Term Synaptic Depression ; physiology ; Male ; Rats ; Rats, Sprague-Dawley

Synaptic ultrastructural changes after long-lasting long-term potentiation (L-LTP) induced by 2 and 100 Hz tetanus were investigated by electron microscopic and stereological approach in slices of the developing rat visual cortex (postnatal days 15~21). Both 2 and 100 Hz tetanus-induced L-LTP groups showed significant increases in synaptic interface curvature, synaptic numeric density and postsynaptic density thickness, as well as significant decreases in the cleft width, as compared with the control groups. In addition, the volume density of the active zone (AZ) was increased significantly in the 100 Hz tetanus-induced L-LTP group, but not in the 2 Hz group. The mean lateral area of individual AZ in the 100 Hz group was relatively higher than that in the 2 Hz group. These data suggest that newly formed synapses in the 100 Hz tetanus-induced L-LTP group are larger than those in the 2 Hz group and that 100 Hz tetanus might trigger reorganization or synthesis of postsynaptic cytoskeleton.
Animals ; Animals, Newborn ; Electric Stimulation ; methods ; Long-Term Potentiation ; physiology ; Male ; Rats ; Rats, Sprague-Dawley ; Synapses ; ultrastructure ; Synaptic Transmission ; physiology ; Visual Cortex ; physiology ; ultrastructure

Previous reports suggested that a novel stimulus pattern of multi-train stimulus at low-frequency (2-Hz or 5-Hz) could induce stable long-term depression (LTD) in the CA1 area of adult rat hippocampus. In the present study, in order to determine the mechanism in LTD induced by the two novel tetanus patterns, changes in the population spikes (PS) in the hippocampal CA1 area of adult rats following the multi-train stimulus in the presence of AP5 [antagonist of N-methyl-D-aspartate receptors (NMDARs)] or MCPG [antagonist of type I/II metabotropic glutamate receptors (mGluRs)] were recorded. The results showed that both AP5 and MCPG inhibited the LTD induced by 2-Hz multi-train stimulus. The mean amplitude of population spikes (PSA) normalized to the baseline was (96.0±3.5)% after applying AP5 (n=10) and (95.7±4.1)% after applying MCPG (n=8), respectively, measured at 20 min post-tetanus. While 5-Hz multi-train tetanus failed to induce LTD in the presence of MCPG. The mean PSA was (73.6±4.4)% (n=10) and (98.2±8.9)% (n=8) in the presence of AP5 and MCPG, respectively, measured at 35 min post-tetanus. So it is suggested that LTD induced by 2-Hz multi-train tetanus involves co-activation of NMDARs and mGluRs, while LTD induced by 5-Hz multi-train tetanus is only related to activation of mGluRs.
2-Amino-5-phosphonovalerate ; pharmacology ; Animals ; CA1 Region, Hippocampal ; physiology ; Glycine ; analogs & derivatives ; pharmacology ; Long-Term Synaptic Depression ; Rats ; Receptors, Metabotropic Glutamate ; antagonists & inhibitors ; Receptors, N-Methyl-D-Aspartate ; antagonists & inhibitors

There is no unambiguous report so far on whether short reinforcing training could establish stable spatial long-term memory and how the NMDA/NR1 expression in the hippocampal formation changes after establishment of short- and long-term memory. In the present study, three spatial memory training modes of Morris water maze were used: spatial long-term memory training mode (LT group), spatial short-term memory training mode (ST group) and short reinforcing training mode (SRT group). The characteristics of those memories established by different training modes were compared. The immunofluorescence histochemical staining technique was used to observe the changes of NMDA/NR1 expression in the hippocampal formation in the three groups. The results showed that, during Morris water maze training, no significant difference was found in the mean latency and the strategies to the target between the LT and SRT groups. The examination of the memories following different trainings indicated that the mean latency and the strategies to the target as well as the times crossing the target in LT group were not significantly different from those in SRT group, except that the mean time remaining in the platform quadrant in LT group was significantly longer than that in SRT group. In addition, no significant difference in the intensity of NMDA/NR1 immunoreactivity in CA1, CA3 and dentate gyrus of the hippocampal formation was observed between the control and ST groups or between LT and SRT groups. However, the intensity of NMDA/NR1 immunoreactivity in CA1 area and dentate gyrus in both LT and SRT groups was significantly increased as compared with that in ST or the control groups. These results suggest that the short reinforcing training mode can establish long-term spatial memory, which is almost the same as that established by the long-term training mode, and that the increase of NMDA/NR1 expression in CA1 area and dentate gyrus of the hippocampal formation may be one of the mechanisms of spatial long-term memory formation.
Animals ; Hippocampus ; chemistry ; physiology ; Male ; Memory ; Memory, Short-Term ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; analysis ; Spatial Behavior

This paper presents a remote controlled multimode micro-stimulator based on the chip nRF24E1, which consists mainly of a micro-control unit (MCU) and a radio frequency (RF) transceiver. This micro-stimulator is very compact (18 mmx28 mm two layer printed circuit board) and light (5 g without battery), and can be carried on the back of a small animal to generate electrical stimuli according to the commands sent from a PC 10 meters away. The performance and effectiveness of the micro-stimulator were validated by in vitro experiments on the sciatic nerve (SN) of the frog, where action potentials (APs) as well as artifacts were observed when the SN was stimulated by the micro-stimulator. It was also shown by in vivo behavioral experiments on operant conditioned reflexes in rats which can be trained to obey auditory instruction cues by turning right or left to receive electrical stimulation ('virtual' reward) of the medial forebrain bundle (MFB) in a maze. The correct response for the rats to obey the instructions increased by three times and reached 93.5% in an average of 5 d. This micro-stimulator can not only be used for training small animals to become an 'animal robot', but also provide a new platform for behavioral and neurophysiological experiments.
Acoustic Stimulation ; Animals ; Behavior Control ; methods ; Conditioning, Operant ; physiology ; Electric Stimulation ; instrumentation ; Equipment Design ; Male ; Medial Forebrain Bundle ; physiology ; Movement ; Rats ; Rats, Sprague-Dawley ; Remote Sensing Technology ; Robotics

The present study investigated the effects of prenatal exposure to the magnetic resonance imaging (MRI) magnetic fields on the synaptic ultrastructure of hippocampal formation of rats at different postnatal development stages. Pregnant rats with gestation of 12-18 days were exposed to the magnetic fields used for MRI clinical applications. When the offspring were 1, 2, or 5-month-old, the synaptic morphologic parameters were measured in female offspring. In the 2-month-old MRI group, the curvature of synaptic interface, the length of active zone and the surface density per unit volume (S(v)) of active zone in the dentate gyrus (DG) decreased significantly, and the width of synaptic cleft increased in the CA1 area. In the 5-month-old MRI group, the width of synaptic cleft increased, the thickness of postsynaptic density and the curvature of synaptic interface decreased significantly in the CA1 region, and the width of synaptic cleft increased in the DG. No significant change was observed in the 1-month-old group. These results suggest that prenatal exposure to the medical magnetic fields causes synaptic ultrastructural changes. The relationship of these changes with behavioral impairments was discussed.
Animals ; Female ; Hippocampus ; pathology ; Magnetic Resonance Imaging ; adverse effects ; Pregnancy ; Prenatal Exposure Delayed Effects ; Rats ; Rats, Sprague-Dawley ; Synapses ; pathology

OBJECTIVETo observe the optimal timing of operation and the therapeutic effect of endoscopic optic nerve decompression for traumatic optic neuropathy (TON).

METHODSThe clinical records of 90 consecutive patients with TON (93 eyes) after head and/or maxillofacial trauma from April 1998 to March 2007 were reviewed and analyzed. All patients were either unresponsive or intolerant to medication before they underwent intranasal endoscopic optic nerve decompression. The time interval between the injury and operation ranged from one day to 97 days (median 5.5 days). Among the 93 eyes, there were 71 eyes with no visual acuity before operation and 22 eyes with residue visual acuity, including light perception in 1 eye, hand movement in 5 eyes, counting fingers in 13 eyes, 0.04 in 1 eye, and 0.1 in 2 eyes. Duration of follow-up ranged from 6 days to two years (median 8 days).

RESULTSAfter decompression, 35 patients (36/93 eyes, 38.7%) showed improvement of visual acuity, 53 patients (55 eyes, 59.1%) remained the same as before operation, while 2 patients (2 eyes, 2.2%) showed decreased visual acuity. Among patients with visual acuity beyond light perception before decompression, 68.2% of them (15/22 eyes) experienced visual improvement, whereas only 22.9% (8/35 eyes, 0.02 in two eyes) among patients who lost visual acuity immediately after injury, and 36.1% (13/36 eyes, 0.02 in five eyes) among those who lost visual acuity gradually after injury. There was a significant difference in visual improvement between group with visual acuity and group with no visual acuity (chi(2) = 11.864, P < 0.01). Among patients with no visual acuity, 41.2% of those (7/17 eyes) who underwent operation within 3 days of injury, experienced improvement in visual acuity, compared with 25.9% (14/54 eyes) for those who underwent the operation more than 3 days after injury. It was indicated that no significant difference in visual improvement between these two groups (chi(2) = 1.46, P > 0.05). When comparing different sites of fracture, the effect of surgery was the most desirable (55.6%, 10/18 eyes improved) if the fracture occurred simultaneously in both exterior and interior walls of optic canal, followed by the interior wall fracture (45.7%, 21/46 eyes). The operation was less effective if there was no fraction (20%, 4/20 eyes) or if the fracture occurred in exterior wall alone (11.1%, 1/9 eyes).

CONCLUSIONSEndoscopic optic nerve decompression is a minimally invasive procedure with no adverse cosmetic effects. Early operation is recommended for saving vision, even though visual acuity is lost immediately after injury. However, the satisfactory clinical effects of endoscopic optic nerve decompression require further study.

Adolescent ; Adult ; Child ; Decompression, Surgical ; methods ; Endoscopy ; Female ; Humans ; Male ; Middle Aged ; Neurosurgical Procedures ; Nose ; surgery ; Optic Nerve Injuries ; surgery ; Treatment Outcome ; Young Adult

OBJECTIVETo investigate the response on late stage Chinese AIDS patients after highly active antiretroviral therapy (HAART).

METHODSFrom October 2002 to March 2004, 20 cases of late stage Chinese AIDS patients were selected to participate in this opened and randomised study, we purposely chose those with CD4+ T cell counts <100/mm3. All of them had one or two opportunistic infections and none had been treated with anti-HIV drugs. All patients were tested with CD4+ (naive CD4+ T cell defined by CD45RA+ and CD62L+, memory CD4+ T cell defined by CD45RA-), CD8+ T cell, plasma HIV viral load, and clinical manifestations on before, during, and after HAART (5 different regimes) on 1, 3, 6, 9, and 12 months.

RESULTSBefore HAART mean CD4+ T cell counts were 32 +/- 31 (range 2-91)/mm3, and plasma HIV viral load were 5.07 +/- 0.85 (range 2.04-5.70) log copies/mL. In 1 month's time patients treated with HAART had mean CD4+ and CD8 T cell counts increasing rapidly. After 1 month the increasing speed turned to slow down, but HIV viral load decreased predominantly within the first 3 months. The major part of increasing CD4+ T cells were memory CD4+ T cells, as fol naive CD4+ T cells increasing low and slow. Clinical symptoms and signs improved, and opportunistic infections reduced. The quality of life will be far much better than before. Each patient was followed for 12 months, and had finished 12 months' HAART.

CONCLUSIONThis is the first report in China that late stage Chinese AIDS patients after HAART could have their immune reconstitution. The regular pattern is similar to what had been reported in Western countries and also in China. So it is worth to treat late stage Chinese AIDS patients with HAART.

Acquired Immunodeficiency Syndrome ; drug therapy ; immunology ; virology ; Adult ; Anti-HIV Agents ; therapeutic use ; Antiretroviral Therapy, Highly Active ; CD4 Lymphocyte Count ; CD4-CD8 Ratio ; CD8-Positive T-Lymphocytes ; immunology ; Didanosine ; therapeutic use ; Female ; Follow-Up Studies ; Humans ; Lymphocyte Count ; Male ; Middle Aged ; Nevirapine ; therapeutic use ; Stavudine ; therapeutic use ; Viral Load

BACKGROUNDThe ghrelin plays an important role in the regulation of food intake and energy homeostasis. Therefore, the ghrelin receptor gene (GHSR) is an excellent candidate for studying metabolic syndrome. This study aimed to investigate whether polymorphisms in ghrelin receptor gene are associated with metabolic syndrome in Chinese population.

METHODSSubjects consisted of 698 patients aged 41 to 80 years, diagnosed as metabolic syndrome by International Diabetes Federation (IDF) 2005 criteria, and 762 age- and gender-matched controls. Three variants within the GHSR were selected and genotyped using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). Odds ratios were estimated using a case-control study design by controlling confounding factors.

RESULTSThe A/A genotype (rs2922126) in the promoter was associated with metabolic syndrome (OR 1.41, 95% CI 1.03-1.94), increased waist circumference (OR 1.75, 95% CI 1.26-2.42), and increased fast blood glucose (OR 1.49, 95% CI 1.07-2.06) in women. The A/A genotype (rs509030) in the intron was associated with lower plasma high density lipoprotein in women (OR 1.37, 95% CI 1.02-1.84).

CONCLUSIONThe polymorphisms within GHSR might be a genetic risk factor for metabolic syndrome in women.

Adult ; Aged ; Cholesterol, HDL ; blood ; Female ; Genotype ; Humans ; Male ; Metabolic Syndrome ; blood ; genetics ; Middle Aged ; Phenotype ; Polymorphism, Single Nucleotide ; Receptors, Ghrelin ; genetics