Serotonergic projections to the rostroventrolateral medulla from midbrain and raphe nuclei

Double-label fluoresence immunohistochemistry was performed to define serotonergic projections from the raphe and midbrain to the sympathoexcitatory region of the rostroventrolateral medulla (RVLM). Immunolabelling of cholera toxin B subunit retrogradely transported from the pressor region of the RVLM was combined with serotonin (5-HT) immunohistochemistry. Major sources of serotonergic input to the RVLM were shown to include the raphe obscurus, raphe pallidus and raphe magnus with a minor contribution from the ventrolateral, lateral and ventral regions of the periaqueductal gray matter, and the dorsal raphe nucleus. Serotonergic modulation of sympathoexcitatory neurons may establish patterns of sympathetic nerve activity evident in many aspects of cardiovascular regulation.     

Phasic but not tonic REM-selective discharge of periaqueductal gray neurons in freely behaving animals: relevance to postulates of GABAergic inhibition of monoaminergic neurons

To determine if ventrolateral periaqueductal gray contains neurons that selectively increase their discharge activity before and during rapid eye movement (REM) sleep, and hence might furnish GABAergic inhibition of monoaminergic neurons, we recorded the extracellular activity of 33 neurons across sleep-wakefulness in freely behaving cats. Several types of state-specific neuronal populations were found in the periaqueductal gray, although we did not find any neurons that had a tonic discharge increase before and during REM. Thus, these data suggest that, although periaqueductal gray neurons may regulate phasic components of REM sleep, they do not have the requisite tonic pre-REM and REM activity to be a source of GABAergic inhibition of monoaminergic neurons.     

图像的阈值分割及其应用

目的 对被检测物体和背景反差较大的图像进行分割。方法 首先绘出要分割图像的灰度直方图；根据直方图选出适当的阈值；最后利用所选定的阈值对图像进行分割。结果 阈值法能把被检测物体和背景反差较大的图像分割。结论 对于被检测物体和背景反差较大的图像，阈值法是一种简单、有效、可靠的分割方法。     

The effect on opioid peptides in the rat brain, after chronic treatment with the anabolic androgenic steroid, nandrolone decanoate

In recent years, an increase in abuse of anabolic androgenic steroids (AAS) has been seen among individuals not directly connected to sports. Clinical evidence suggests that abuse of these steroids may result in profound changes in personality, expressed by depressive symptoms, irritability and increased aggression. It is still unknown whether these alterations are related to changes in any particular transmitter system or whether they are persistent or reversible. In this study we focused on AAS effect on the endogenous dynorphin and enkephalin system in the brain. Male rats were given intramuscular injections of the AAS nandrolone decanoate (15 mg/kg), once daily for 2 weeks. The levels of the opioid peptide immunoreactivities (ir) were assessed by radioimmunoassay in two groups immediately after the treatment and in two other groups after additional 3 weeks without any drug treatment (recovery period). The result indicates that chronic AAS treatment increased the activity in the dynorphin B- and Met-enkephalin-Arg(6)Phe(7)-ir in the hypothalamus, striatum and periaqueductal gray (PAG) compared to controls. In addition, the steroid induced an imbalance between the dynorphin and the enkephalin opioid system in the nucleus accumbens, hypothalamus and PAG. This imbalance remained after the recovery period. Since increased peptide activity was found in brain regions regulating emotions, dependence, defensive reactions and aggression, it was suggested that the actual endogenous opioid systems are involved in previously reported AAS-induced changes in these behaviours.     

用扫描仪评价不同产地赤芍提取物对红细胞聚集的抑制作用

为了解不同产地赤芍乙醇提取物对于红细胞聚集的影响 ,本文采用扫描仪对此进行了评价。用葡聚糖 5 0 0诱导大鼠红细胞在体外悬浮液中的聚集 ,观察终浓度 138mg/ml的赤芍提取物对此的影响。实验表明 ,细胞悬浮液扫描图象的灰度与红细胞悬浮液的细胞聚集程度有显著相关。实验结果表明 ,六个产地中的四个赤芍提取物对于红细胞聚集有明显抑制 ,其中内蒙古多伦出产的赤芍效果最明显 (P <0 0 0 1)。结果可说明药材的道地性     

Acute disseminated encephalomyelitis associated with Mycoplasma pneumoniae infection

An 8 year old girl with acute disseminated encephalomyelitis (ADEM) is described. Elevated serum antibody titers suggested recent Mycoplasma pneumoniae infection. T2-weighted image of magnetic resonance imaging (MRI) disclosed multiple lesions of high signal intensity in bilateral basal ganglia and thalami as well as in the white matter. Postcontrast T1-weighted image revealed an enhanced lesion in the deep white matter. She showed rapid clinical improvement in response to corticosteroid therapy. The lesions had disappeared completely on MRI performed 10 weeks after the onset. ADEM is believed to be a demyelinating disorder of probable autoimmune etiology. MRI findings in this case may support the hypothesis that the primary pathological event is vascular injury and demyelination occurs only as a secondary phenomenon.     

A case of West syndrome with atypical massive gray matter heterotopia that is well controlled by ACTH therapy

A 4 month old female infant with atypical asymmetrical massive gray matter heterotopia diagnosed as West syndrome is described. Her seizure initially appeared as afebrile general tonic and clonic convulsion and progressed to typical West syndrome consisting of clusters of myoclonic spasms of the extremities, mainly on the left side, accompanied by head and eye deviation to the right side. Electroencephalogram (EEG) presented typical hypsarrhythmia and cranial computerized tomography (CT) and magnetic resonance imaging (MRI) showed massive heterotopic gray matter in the right hemisphere with the same density or intensity as cortical gray matter. Single photon emission computed tomography (SPECT), using N-isopropyl-p-¹²³I-iodoamphetamine (¹²³I-IMP), demonstrated decreased blood flow in the ectopic lesion. Although clinical response to several anti-epileptic drugs was poor, her seizures were well controlled by relatively low dose adrenocorticotropic hormone (ACTH) therapy of 0.015 mg/kg per day followed by a combination of valproic acid and clonazepam.     

Lesions of the central gray block the sensitization of the acoustic startle response in rats

The amplitude of the acoustic startle response (ASR) in rats is increased after administration of footshocks, a phenomenon termed sensitization. The neural circuitry underlying this kind of modulation of the ASR is only partly understood. It has been shown that the central nucleus of the amygdala (cA) and its efferent pathway to the caudal pontine reticular nucleus (PnC), an essential part of the primary startle circuit, is important for the sensitization of the ASR [23]. It was unclear, however, whether the amygdaloreticular pathway directly transfers the effects of footshocks onto the PnC, or whether there exists a relay nucleus within this pathway. The present study tested the hypothesis that the midbrain central gray (CG) is important for the sensitization of the ASR. Neuroanatomical tracing experiments indicate that a descending projection from the medial part of the cA might form synapses in the region of the midbrain CG, where a descending projection to the PnC takes its origin. We lesioned the dorsal and lateral part of the CG with the neurotoxin quinolinic acid and measured the effects of this lesion on the sensitization of the ASR by footshocks. Lesions confined to the dorsal and lateral parts of the CG totally blocked the sensitization of the ASR, without affecting the ASR amplitude in the absence of sensitizing stimuli. These findings suggest a crucial role of the CG for the sensitization of the ASR. The present data are reconciled with other findings from our laboratory and from the literature and we discuss possible mechanisms underlying the mediation of the sensitization of the ASR in rats.     

Anatomical and functional connections of neurons of the rostral medullary raphe of the rabbit

Single cell recordings were made from neurons in the rostral medullary raphe (RMR) of the rabbit. The recording sites were ones that had been shown to yield pressor responses from electrical stimulation and by pressure injections of glutamate. Electrical stimulation of the intermediolateral (IML) region of the spinal cord led to antidromic activation of 12 of the 100 cells studied. Eleven of these cells were located in raphe pallidus or raphe magnus, and one cell was located in raphe obscurus. These findings were consistent with the results of horseradish peroxidase (HRP) histochemistry experiments. Injections of HRP into the IML led to heavy cell body labeling in raphe pallidus and raphe magnus, but sparse labeling in raphe obscurus. Cells in the RMR could be orthodromically activated by electrical stimulation of the putative defense area of the periaqueductal (PAG) but not by stimulation of putative defense areas in the hypothalamus. Most of these cells were located in raphe pallidus or raphe magnus. Similarly, HRP injections into raphe pallidus and raphe magnus led to heavy cell body labeling in the PAG but not the hypothalamus; no cell body labeling was found in the PAG when injections were made into raphe obscurus.     

Repeated spinal cord stimulation decreases the extracellular level of γ-aminobutyric acid in the periaqueductal gray matter of freely moving rats

Most of the previous experimental studies on the antinociceptive effects of electrical spinal cord stimulation (SCS) have focused on short-lasting effects mainly depending on spinal mechanisms. However, patients treated with SCS for chronic pain often report pain relief exceeding the period of stimulation for several hours. The long lasting effect of SCS might not only involve spinal, but also supraspinal mechanisms. A supraspinal region of major importance for the coordination of descending pain inhibition is the periaqueductal grey matter (PAG). The aim of the present microdialysis study, performed in awake freely moving rats, was to investigate if repeated SCS (two 30 min periods separated by a 90 min resting period) alters the extracellular neurotransmitter concentrations in the ventrolateral PAG. In a first series of experiments significantly decreased (−30%;P < 0.05;n = 7) γ-aminobutyric acid (GABA) levels were detected immediately after the second SCS session. Neither the concentration of serotonin nor that of substance P-like immunoreactivity (SP-LI) was affected by SCS. The decrease of GABA after two SCS sessions was confirmed in a second series of experiments (−30%;P < 0.05;n = 7). No spontaneous decline of GABA was observed in sham-stimulated animals (n = 6). The glutamate concentration was also determined in this latter series of experiments and a significant decrease (−23%;P < 0.05;n = 5) was observed after the second SCS session. As GABA-neurons in the PAG exert a tonic depressive effect on the activity in descending pain inhibitory pathways, a decreased extracellular GABA level in this region, as detected following repeated SCS, might indicate an increased pain inhibition.