棉酚对大鼠下丘脑超微结构影响的观察

本文观察了棉酚对雄性成年大鼠下丘脑弓状核、视上核和室旁核细胞超微结构的影响。棉酚以每日30mg/kg体重给大鼠灌服,连续5周。结果表明服棉酚后,视上核和室旁核变化不明显;而弓状核中,部分细胞呈现一系列神经分泌功能增强的变化,高尔基复合体和粗面内质网轻度扩张,内充均质低电子密度物质;神经分泌颗粒、溶酶体、核仁样体和微管数量增多。本文并对以上超微结构改变的性质、意义和可能原因进行了讨论。     

Dissociating the determinants of self-stimulation

Four experiments were conducted to elucidate the determinants of the initiation of and escape from electrical stimulation of the lateral hypothalamus under several different reinforcement schedules. The first experiment of this series used correlational and factor analytic techniques to show that, under continuous reinforcement, the vigour of initiation is determined more by forcement than by positive reinforcement. Forcement is defined as all of the performance changes directly elicited and potentiated by the stimulation. Escape is determined by adaptation of positive reinforcement, not by negative reinforcement or aversion. Continuous reinforcement schedules are, therefore, not appropriate for studying either the positive or negative reinforcement produced by brain stimulation. The second experiment used fixed-interval reinforcement schedules to eliminate the effects of forcement on initiation and adaptation of positive reinforcement on escape. Parametric manipulations indicate that activity in the positive reinforcement and escape systems is a simple function of stimulation charge. The combination of parameters which make up a given charge is of relatively little importance. However, the positive reinforcement system becomes maximally activated at far lower charges than does the escape system. The third experiment used a T-maze technique to show that, after 5 sec, anterior hypothalamic stimulation becomes negatively reinforcing, but posterior hypothalamic stimulation does not. Since the escape from posterior hypothalamic stimulation on a fixed-interval schedule can be dissociated from both negative reinforcement and adaptation of positive reinforcement, it is suggested that such escape is reinforced by a positive process triggered by the offset of stimulation (OFF positive reinforcement). The fourth experiment showed that stimulation trains longer than 10 sec are significantly less positively reinforcing than much shorter trains. This reduction in positive reinforcement confirms the development of negative reinforcement in long trains of hypothalamic stimulation, even at posterior electrodes. Negative reinforcement appears to be as general a property of hypothalamic stimulation as is positive reinforcement. Thus, depending on the reinforcement schedule and electrode site, the initiation of lateral hypothalamic stimulation may be determined by ON positive reinforcement, OFF positive reinforcement and forcement. Escape may be determined by OFF positive reinforcement, adaptation of positive reinforcement and negative reinforcement.(ABSTRACT TRUNCATED AT 400 WORDS)     

Lateral hypothalamic lesions facilitate hepatic regeneration after partial hepatectomy in rats

It has been reported that ventromedial hypothalamic lesions facilitate hepatic regeneration through the hepatic vagal nerve after partial hepatectomy. However, whether the lateral area of the hypothalamus is involved in liver regeneration after partial hepatectomy is unknown. To determine the role of the lateral hypothalamic area in this phenomenon, we studied hepatic DNA synthesis during liver regeneration after partial hepatectomy with bilateral lesions of the area. Lesioning of the lateral hypothalamus accelerated the increase in hepatic DNA synthesis and raised the peak level of [methyl-³H]thymidine incorporation after partial hepatectomy. These effects of hypothalamic lesioning were inhibited by combined hepatic vagotomy and sympathectomy. Our results demonstrate that lesioning of the lateral hypothalamus promotes hepatic regeneration through the autonomic nervous system after partial hepatectomy and suggest that the lateral hypothalamic area is involved in liver regeneration through neural mediation.     

Effects of Induced drinking on self-stimulation of the Lateral Hypothalamus

Summary Rats with chronic electrodes in the lateral hypothalamus were induced by electrical stimulation to self-stimulate and drink. The effect of this artificially-elicited drinking on self-stimulation behavior was investigated. Self-stimulation rates at optimal current levels were not changed by induced water intake. However, with the current level just above threshold for self-stimulation the rate was increased significantly when the animals were able to self-stimulate and drink simultaneously. It is suggested that sensory feed-back from the consummatory behavior facilitates the activation of neural circuits in the lateral hypothalamus so that low current stimulation more effectively reinforces self-stimulation.     

Corticotrophin and corticosterone secretion following Δ1-tetrahydrocannabinol,in intact and in hypothalamic deafferentated male rats

Summary Adult male rats, either intact (N) or bearing complete hypothalamic deafferentations (CHD), were injected with 1-tetrahydrocannabinol (THC: 5 mg/kg BW, IP). Forty-five minutes later, they were decapitated and trunk blood was collected for serum ACTH and corticosterone (CS) determinations. In the N animals, serum levels of both ACTH and CS were markedly elevated in the drug-treated, as compared to the vehicle-treated group (approximately 8-fold and 10-fold, respectively). In CHD rats, on the contrary, THC administration did not significantly alter serum concentrations of either ACTH or CS. These results demonstrate (1) that acute treatment with THC stimulates the secretion of ACTH as well as of CS; and (2) that extrahypothalamic sites and/or neural pathways mediate this effect.     

Effects of hypothalamic deafferentations on adrenocortical responses in the rat following hippocampal stimulation

Summary Adrenocortical responses, as expressed by changes in plasma corticosterone levels, following ether stress and dorsal hippocampal stimulation, were studied in intact rats and in rats with complete, anterior or posterior hypothalamic deafferentations. Ether stress produced normal responses in all experimental groups. In the three groups with hypothalamic deafferentations, the adrenocortical response following hippocampal stimulation was completely blocked, when compared to intact animals. The results suggest that the hippocampal signal enters the hypothalamus anteriorly, but that caudal propagation and posterior re-entry into the hypothalamus are also essential for the adrenocortical activation by the hippocampus.Supported by US-Israel Binational Foundation grant 1554/78     

儿童下丘脑错构瘤的诊断与治疗

目的 探讨儿童下丘脑错构瘤的诊断和治疗。方法 对18例儿童下丘脑错构瘤的临床特点进行分析;应用CT,MRI进行诊断。手术除1例采用经络板入路外,有10例采用经翼点入路切除错构瘤;其他病例采用γ刀或药物治疗。结果 其临床表现特点为痴笑样癫痫和性早熟,少数病例有其他类型癫痫,智力低下或合并先天畸形,CT和MRI显示脚间池或垂体柄后上方有等信号改变,注药后无强化,18例中,手术治疗11例,有效率为91％（10／11）,对单纯性早熟者可治愈,γ刀治疗36Gy大剂量有效1例,无效2例,药物治疗对性早熟有效,但对痴笑样癫痫及其他癫痫发作无效。结论 下丘脑错构瘤首选手术治疗。     

Paraventricular area: Critical focus of a longitudinal neurocircuitry mediating food intake

Hyperphagia, obesity, and excessive linear growth, but not hyperdipsia, were produced by the asymmetrical combination of a parasagittal hypothalamic knife cut and a contralateral coronal knife cut. When the location of the coronal cut was varied systematically, it was found that cuts rostral to the coronal level of the paraventricular nucleus (PVN) neither produced nor prevented overeating, while cuts caudal to the PVN produced a robust hyperphagic response. Thus, the coronal level of the paraventricular nucleus was revealed as the rostral focus of a longitudinal satiety neurocircuitry.     

邻苯二甲酸单乙基己基酯对原代培养新生雌性大鼠下丘脑神经元生殖神经内分泌相关基因表达影响

目的探讨邻苯二甲酸单乙基己基酯(mono-2-ethylhexyl phthalate,MEHP)对新生雌性大鼠下丘脑生殖神经内分泌功能的影响。方法对出生24h内的新生雌性SD大鼠下丘脑神经元进行原代培养,分别暴露于含终浓度为0(对照)、10~(-15)、10~(-12)、10~(-9)、10~(-6)mol/L MEHP的培养基染毒24h。采用qRT-PCR法检测Gn RH、Gn RHr、Kiss1及Kiss1r基因的表达水平。结果与对照组相比,各浓度MEHP暴露组原代培养新生雌性大鼠下丘脑神经元Kiss1基因的表达水平均较低,差异有统计学意义(P0.05);而Gn RH、Gn RHr和Kiss1r基因的表达水平均无明显改变。结论 MEHP有可能通过下调新生雌性大鼠下丘脑神经元Kiss1基因表达水平来干扰生殖神经的内分泌调控功能。