The role of noradrenaline in the generation of the preovulatory LH surge in the ewe

Increasing plasma estrogen (E) levels during the follicular phase of the estrous cycle trigger the pre-ovulatory surge of gonadotropin-releasing hormone (GnRH)/LH. Noradrenaline (NA)-producing cells of the brain stem are involved in regulating GnRH cells and project to the preoptic area (POA) and bed nucleus of stria terminalis (BnST). Input to GnRH cells may be direct or indirect, via relay neurons in the POA/BnST. To investigate this, we ascertained whether an ₁-adrenergic antagonist would block/delay the LH surge in ovariectomised (OVX), E-treated ewes. E benzoate (EB) (50 μg) was injected (i.m.) and Doxazosin (100 nmol/h) or vehicle was infused into the third ventricle 2–26 h after EB injection. Doxazosin reduced the magnitude of the LH surge, but did not affect timing. To determine if NA is released in the POA/BnST of cyclic ewes, we immunostained dopamine-β-hydroxylase (DBH) in terminal fields. Reduced numbers of varicosities staining for DBH indicates release of NA. The number of varicosities immunostained for DBH was reduced in the dorsal and lateral BnST during the follicular phase and during the preovulatory LH surge compared to the luteal phase. These data suggest that noradrenergic mechanisms are involved in generation of the GnRH/LH surge via projections to the BnST and relay to GnRH cells. Since Doxasozin reduced the magnitude of the LH surge in the E-treated OVX ewe, and release of NA in cyclic ewes occurred during the follicular phase of the estrous cycle, we speculate that NA is a permissive factor in surge generation. Thus, increased noradrenergic activity is not a trigger mechanism for initiation of the surge.     

Changes in brain and pituitary GnRH levels during ovarian maturation in wild female Japanese flounder

To elucidate the role of gonadotropin-releasing hormone (GnRH) in gonadal maturation in wild female Japanese flounder Paralichthys olivaceus, we monitored changes in the levels of seabream GnRH (sbGnRH) in the olfactory bulb, telencephalon, hypothalamus, and pituitary during ovarian development together with changes in plasma levels of testosterone (T), estradiol-17β (E₂), and 17α, 20β-dihydroxy-4-pregnen-3-one (DHP). Fish were caught offshore of the northern mainland of Japan in the Pacific Ocean at 3- to 4-week intervals between April and September by gill net. The netted fish were categorized into six groups based on ovarian stages: previtellogenic (April–early May), early yolk (April–late May), late yolk (late May–June), early spawning (June–August), late spawning (September), and termination (September) stages. The gonadosomatic index significantly increased from the previtellogenic to early spawning stages and decreased thereafter. In the olfactory bulb, no significant differences were observed in sbGnRH levels among the developmental stages. In contrast, sbGnRH levels in the telencephalon and hypothalamus were very high in the previtellogenic stage, lower in the early spawning stage, and relatively high in latter stages. sbGnRH levels in the pituitary were high in the previtellogenic stage and low in the early spawning stage. In addition, the relatively high levels of pituitary sbGnRH were found together with high plasma T, E₂, and DHP levels in fish in the late yolk stage. These results indicate that sbGnRH in the telencephalon, hypothalamus, and pituitary is involved in ovarian maturation and that sbGnRH may play an important role in the initiation of ovarian recrudescence in wild Japanese flounder.     

急性中毒性脑病的CT诊断

目的探讨急性中毒性脑病的CT表现,提高对本病的认识.方法收集急性中毒性脑病18例,回顾性分析其脑部CT表现特点.结果CT表现：脑水肿18例,脑实质密度减低,脑室及脑池受压变小,严重者全脑密度呈均一性减低;蛛网膜下隙出血14例,表现为后纵裂池及天幕等处条片状高密度影;脑内出血2例,呈斑片状高密度影.结论CT能够反映中毒性脑病的病变范围、严重程度和预后情况,对临床及时正确诊治,减少后遗症具有重要意义.     

出生前山羊脑和脊髓的生长发育规律

测量了6～21周山羊胎儿脑和脊髓的相关指标,并绘制生长曲线.结果表明:山羊胎儿脑和脊髓生长发育具有快慢交替的阶段性变化规律.发育早期脑的生长速度要快于同期脊髓的生长速度.出生前,山羊大脑在长、宽、高3个方向上的发育表现出不均衡的特点.脊髓不同节段的生长高峰期出现的时间、数量和增长趋势都不一致,可能与脊髓内不同组份发育先后次序有关.     

Effect of carbon monoxide on permeability of brain blood barrier in cerebral local ischemia rats

AIM:To evaluate the effect of carbon monoxide(CO) on the permeability of brain blood barrier(BBB) in cerebral ischemic rats. METHODS:SD rats were divided into three groups. Saline, hemin or ZnPP were injected intraperitoneally 12 h before middle cerebral artery occlusion (MCAO), respectively. The concentration of blood CO and the permeability of BBB at 24 h after MCAO were measured. RESULTS:The CO concentration in blood in hemin group was higher than that in saline group(P＜0.01), but those in ZnPP group was lower than that in saline group(P＜0.01). In infracted regions, the permeability of BBB in hemin group was lower than that in saline group, and those in ZnPP group was higher than that in saline group (P＜0.05). There was no significant changes in BBB permeability among hemin, ZnPP and saline groups in noninfarcted side(P＞0.05). CONCLUSION:CO reduced the permeability of BBB as a messenger gas molecular when its intrinsic concentration was elevated.     

八种鲤科鱼类脑的形态构造观察

本文描述了八种鲤科鱼类脑的外部形态和显微结构，并对不同水层鱼的脑进行了比较。鲤科鱼类的脑除了延脑有显著差异外，其它基本相似。鱼脑的形态构造不完全决定于分类系统，在很大程度上取决于它的生态环境和习性．因此，以鱼脑的形态构造差异，作为分类的鉴别特征是不适宜的。在生活习性相同的鱼类中，脑的形态构造越相似，其亲缘关系越近。     

Effects of adenosine A1 receptor antagonist DPCPX on cerebral neurons after hypoxia and reoxygenation

AIM: To investigate the effects of adenosine A₁ receptor antagonist DPCPX on the release of cerebral neuronal lactate dehydrogenase (LDH), the activity of calcineurin (CaN) and acetylcholinesterase (AChE), and the level of extracellular amino acid after hypoxia and reoxygenation (H/R).METHODS: Primary cultured rat cerebral cortical neurons were used to establish an H/R injury model. Different concentrations of DPCPX (the final concentrations were as follows: 0, 25, 50 and 100 nmol/L) were added at the same time of hypoxia treatment for 8 h, 12 h or 24 h,followed by reoxygenation for 24 h. The LDH release from the neurons was measured. The effects of DPCPX (100 nmol/L) on the activity of CaN and AChE, and the level of extracellular amino acid in neurons treated with hypoxia for 12 h followed by reoxygenation were observed. RESULTS: Compared to the cells in control groups, the neurons treated with 100 nmol/L DPCPX and exposed to hypoxia for 12 h followed by reoxygenation, showed significantly higher LDH release, higher activity of CaN and AChE, and lower level of extracellular γ-aminobutyric acid.CONCLUSION: These results suggest that DPCPX increases the LDH release and the activity of CaN and AChE, decreases the level of extracellular γ-aminobutyric acid in neurons with H/R.     

JNK pathway promotes apoptosis of rat hippocampal neurons after cerebral ischemia and reperfusion

AIM:To investigate the effect of c-Jun N-terminal kinase(JNK) pathway on the apoptosis of hippocampal neurons after cerebral ischemia-reperfusion(IR) in SD rats. METHODS:Ninety rats were randomly divided into 5 groups:sham group, cerebral IR group,cerebral IR+JNK inhibitor(SP600125) group,cerebral IR+JNK agonist(anisomycin) group and cerebral IR+vehicle group. The brain samples were collected 24 h after reperfusion. The protein level of caspase-3 in hippocampal neurons was measured by immunohistochemical and Western blotting techniques. The mRNA expression of caspase-3 in the hippocampus was determined by real-time fluorescence quantitative PCR. The apoptosis of hippocampal neurons was detected by TUNEL staining. RESULTS:Compared with sham group, the expression of caspase-3 at mRNA and protein levels in cerebral IR group increased obviously(P<0.05). Compared with cerebral IR group, the expression of caspase-3 at mRNA and protein levels in cerebral IR+JNK inhibitor group decreased obviously(P<0.05), and those in cerebral group increased obviously(P<0.05). However, the expression of caspase-3 at mRNA and protein levels in cerebral IR+vehicle group had no obvious change(P>0.05).The apoptosis of hippocampal neurons in each group was consistent with the changes of caspase-3 at mRNA and protein levels. CONCLUSION:Activation of JNK pathway enhances caspase-3 expression in rat hippocampal neurons after cerebral IR,thus promoting the apoptosis of the neurons.     

Apoptosis mechanism by which diabetes aggravate brain damage

Many clinical and basic researches have revealed that brain damage can be deteriorated by diabetes significantly.However,its pathogenesis remains unclear.Recently,apoptosis have become the focus of research on brain damage.This article introduces the related investigations.     

Changes and significance of ATPase and free radical in aged rats with brain ischemia-reperfusion

AIM: To study the mechanism of brain ischemia-reperfusion injury from ATPase activity and free radical metabolism in aged rats. METHODS: The young rats (5 months) and the aged rats (more than 20 months) were divided into young control group(YCG), young model group(YMG), aged control group(ACG) and aged model group(AMG). The ATPase and SOD activities and the contents of MDA, Ca^2＋, Na^＋ and K^＋ were measured in the rats with 30 min brain ischemia followed by 60 min reperfusion. RESULTS: The Ca^2＋content in the AMG was higher than that in the YMG and the ACG. The Na^＋-K^＋-ATPase activity in the ACG was lower than that in the YCG,was lower in the AMG than that in the YMG. The Ca^2＋-ATPase activities in the YCG was higher than that in the ACG, was lower in the AMG than that in the YMG and was higher than the ACG's. The serum and brain tissue SOD activities in the ACG was lower than that in the YCG, was lower in the AMG than YMG 's. The serum and brain tissue MDA/SOD ratio in the AMG was higher than that in the ACG.CONCLUSION:The brain tissue ischemia-reperfusion injury was related with calcium overload and free radical injury.The pathological changes were obvious and had some characteristics in the aged rats compared with the young rats because of the brain t issue aging changes in ATPase,calcium content and free radical metabolism in the aged rats.