侧脑室注射Orexins对大鼠摄食的影响及机制

目的:探讨侧脑室注射orexins(食欲素)、NPY(神经肽Y)、MCH(黑色素聚集激素)和甘丙肽对大鼠摄食的影响及其机制。方法:将成年雄性Wistar大鼠随机分为对照组、侧脑室注射组和室旁核(PVN)注射组。通过套管将orexin-A、orexin-B、NPY、MCH和甘丙肽分别注射至侧脑室和PVN内,随后测量大鼠食物摄入量,并检测PVN、弓状核(ARC)和VMH内c-fos的表达。结果:与对照组比较,侧脑室注射NPY、MCH和orexin-B 2 h后,大鼠摄食量显著增多(P0.05)。相较于orexin-B和MCH,NPY对摄食的影响更显著(P0.05)。与NS对照组比较,侧脑室注射甘丙肽和orexin-A 1 h后,大鼠摄食量显著增多(P0.05)。与NS对照组比较,侧脑室注射orexin-A可显著增加c-fos在PVN和ARC中的表达,在VMH中效应较弱(P0.05)。与NS对照组比较,PVN注射NPY能显著增加大鼠2 h摄食量(P0.05),PVN注射orexin-A能显著增加大鼠2 h和4 h摄食量(P0.05)。结论:orexins与可促进大鼠摄食,此效应可能通过下丘脑参与摄食调控中枢PVN和ARC而实现的。     

Nesfatin-1对大鼠摄食、胃酸分泌、胃运动及胃排空的影响

目的:观察Nesfatin-1对大鼠摄食、胃酸分泌、胃运动及胃排空的影响并探究其可能机制。方法:将大鼠随机分为摄食实验组、胃酸实验组、胃运动实验组以及胃排空实验组。大鼠经腹内侧核置管后给予nasfatin-1,检测大鼠摄食量,使用Na OH滴定法测定大鼠胃酸分泌,记录清醒大鼠胃运动,以比色法测定大鼠胃排空。结果:低剂量和高剂量nesfatin-1均减少2小时累积食物摄入量;高剂量组4小时累积食物摄入量仍显著低于NS对照组。Nesfatin-1能够抑制2-DG对胃酸分泌的促进作用。SHU9119能够部分阻断nesfatin-1对2-DG的抑制作用。Nesfatin-1能够抑制胃运动及胃排空,SHU9119可部分阻断nesfatin-1对胃运动及胃排空的抑制作用。结论:Nesfatin-1能够调控大鼠摄食、胃酸分泌、胃运动及胃排空,黑皮质素信号通路可能也参与该调控过程。     

中枢精氨酸加压素在大鼠促肾上腺皮质激素释放激素释放激素引起发热机制中的作用

实验对大鼠进行第三脑室和脑腹中隔区插管,用数字体温计测量大鼠的结肠温度,用放射免疫分析法测定脑中隔区精氨酸加压素（arginine vasopressin,AVP）含量,观察脑中隔区AVP在大鼠促肾上腺皮质激素释放激素（corticotrophin releasing hormone,CRH）性发热机制中的作用。结果发现：脑室注射CRH（5.0μg）引起大鼠结肠温度明显升高,同时明显增高脑中隔区AVP的含量。脑腹中隔区注射AVP V1受体拮抗剂本身并不导致大鼠结肠温度明显改变,但能显著增强脑室注射CRH引起的发热反应。而且,腹中隔区注射AVP显著抑制大鼠CRH性发热。结果提示：发热时CRH是引起脑腹中隔区AVP释放的因素之一,脑腹中隔区内源性AVP抑制中枢注射CRH引起的体温升高。     

中枢注射Nesfatin-1与Exendin(9-39)对大鼠摄食和胃肠动力调节的影响

目的:探讨下丘脑室旁核注射GLP-1R拮抗剂Exendin(9-39)对Nesfatin-1所致大鼠摄食和胃肠动力改变的影响及作用机制。方法:选择40只雄性Wistar大鼠,随机分成正常对照组(NC组)、Nesfatin-1组(NS组)、Exendin(9-39)组(ES组)、Nesfatin-1联合Exendin(9-39)组(NE组)。采用下丘脑室旁核(PVN)埋置套管并分别给予以上药物干预,干预前和干预后的12小时、24小时记录和比较各组大鼠的摄食、饮水及体重变化。2天后,采用甲基纤维素-酚红溶液灌胃法测各组大鼠胃排空率,实时荧光定量法(RT-PCR)检测下丘脑及胃组织GLP-1Rm RNA的表达。结果:与基础摄食量比较,NS组大鼠给药后12 h、24 h的摄食量减少(P0.05),NE组大鼠给药后12 h、24 h的摄食量减少(P0.05),但较NS组增加(P0.05);与基础饮水量比较,NS组、NE组给药后12 h饮水量减少(P0.05);与基础体重比较,NS组大鼠给药后12 h、24 h的体重降低(P0.05),NE组大鼠给药后12 h的体重降低(P0.05),但较NS组增加(P0.05);NS组大鼠给药后胃排空率较NC、NE组大鼠显著下降(P0.05),NS组大鼠下丘脑GLP-1Rm RNA的表达量较NC组增加(P0.05)。结论:中枢给予GLP-1R拮抗剂能减弱Nesfatin-1引起的摄食抑制、胃排空延迟及体重下降效应,Nesfatin-1可能通过与GLP-1的协同作用参与摄食及胃肠动力的调节。     

中枢nesfatin-1对大鼠夜间摄食和胃排空的影响

目的:观察中枢nesfatin-1对大鼠夜间摄食和胃排空的影响。方法:大鼠经腹腔注射硫酸仲丁巴比妥(100~150 mg/kg)麻醉,侧脑室、第四脑室或小脑延髓池注射nesfatin-1或CRF受体拮抗剂astressin-B或astressin2-B,观察对摄食、胃排空的影响。结果:侧脑室注射nesfatin-1后大鼠第3-6 h夜间进食量(t=3.05~3.58,P0.01)和3 h和6 h的累积进食量(t=5.90~12.1,P0.01)明显减少,nesfatin-1的该抑制效应可被预先侧脑室注射astressin-B或astressin2-B阻断(t=1.06~2.22,P0.05)。第四脑室或小脑延髓池注射nesfatin-1后大鼠夜间摄食量在第1h就明显减少(t=2.59~6.26,P0.05~0.01),持续减少至5-6h(t=1.69~7.42,P0.05~0.01)。侧脑室注射不同剂量nesfatin-1(0.05或0.5μg)20 min后GE率明显降低,且随注射剂量增大,GE率越低(t=3.25~4.67,P0.01)。若预先给予大鼠CRF受体拮抗剂astressin2-B(30μg)再注射nesfatin-1(0.5μg),nesfatin-1抑制大鼠胃排空效应明显减弱(t=2.45~2.85,P0.05)。禁食24 h后再喂食2 h,大鼠下丘脑中nesfatin-1表达明显增加(t=2.87,P0.05),禁食24 h后血浆nesfatin-1水平明显降低(t=1.51,P0.05)。结论:Nesfatin-1抑制摄食作用可能由nesfatin-1和CRF2信号系统共同调节。     

下丘脑腹内侧核损毁对大鼠nesfatin-1/NUCB2表达的影响

目的:观察下丘脑腹内侧核(VMH)损毁对大鼠脂肪组织nesfatin-1/NUCB2表达的影响及其机制。方法:电损毁VMH,观察大鼠体重和脂肪组织变化,采用Western blot检测脂肪组织中nesfatin-1/NUCB2表达改变。腹腔注射6-羟多巴胺(50 mg/kg)以阻断交感神经;持续外周注射卡巴胆碱(180μg/kg)用以模拟VMH损毁,观察其对大鼠皮下脂肪nesfatin-1/NUCB2表达的影响。结果:与对照组和假手术组比较,VMH损毁后大鼠体重明显增加(P0.05),皮下脂肪(P0.05)和肠系膜脂肪(P0.05)也显著增多;Western blot分析结果显示,nesfatin-1/NUCB2在胰腺和肝脏中表达较多,但皮下、肠系膜脂肪和肩胛间棕色脂肪组织(i BAT)中表达较少,骨骼肌(腓肠肌)中鲜有表达;与对照组和假手术组比较,VMH损毁组大鼠nesfatin-1/NUCB2在肝脏、胰腺、骨骼肌和i BAT中表达无显著差异(P0.05),皮下脂肪(P0.05)和肠系膜脂肪(P0.05)nesfatin-1/NUCB2表达显著增多与对照组相比,6-羟多巴胺组nesfatin-1/NUCB2表达显著升高(t=3.43,P0.05),而卡巴胆碱组nesfatin-1/NUCB2表达无显著差异(t=0.37,P=0.72)。结论:VMH损毁后大鼠脂肪组织nesfatin-1/NUCB2表达改变可能通过抑制交感神经活动介导。     

侧脑室注射促甲状腺激素释放激素对大鼠睡眠—觉醒的影响

采用多导睡眠描记术研究了例脑室注射促甲状腺激素释放激素(TRH)对正常大鼠和去甲状腺大鼠睡眠-觉醒的影响。在正常大鼠,TRH引起觉醒增加,浅慢波睡眠(SWS_1)、深慢波睡眠(SWS_2)和总睡眠时间(TST)均减少,异相睡眠(PS)消失,SWS_1、SWS_2和PS的潜伏期均显著延长,给药后立即产生效应并在1h内达高峰。去甲状腺对大鼠的睡眠-觉醒无明显影响,注射TRH后引起的效应与正常大鼠相似。结果提示TRH有促进大鼠觉醒的作用,对各睡眠时相均有抑制作用,其作用部位可能在下丘脑以外的中枢结构。     

下丘脑室旁核orexin-A对大鼠摄食和胃动力影响及调控机制

目的:探讨下丘脑室旁核orexin-A对大鼠摄食和胃动力影响及调控机制。方法:采用免疫组化观察下丘脑室旁核(paraventricular nucleus,PVN)orexin受体表达情况;PVN注射orexin-A观察大鼠摄食、胃运动、胃酸分泌和胃排空的改变。结果:免疫组化实验显示大鼠PVN中存在orexin受体免疫阳性细胞。PVN注射orexin-A后,大鼠前三小时摄食增加,6 h和24 h摄食无显著改变。PVN微量注射orexin-A后,大鼠胃运动幅度和频率增加、胃排空增快并且胃酸分泌增多。[D-Lys-3]-GHRP-6可部分阻断orexin-A对摄食、胃运动、胃排空和胃酸分泌的促进作用,SB334867可完全阻断orexin-A对胃运动、胃排空和胃酸分泌的促进作用。结论:下丘脑室旁核orexin-A可能通过生长激素促泌素GHSR受体信号通路调控大鼠摄食及胃功能。     

大鼠下丘脑LHA-PVN nesfatin-1神经通路构成及对胃运动的影响

目的:阐述LHA和PVN间nesfatin-1神经通路的构成,探讨PVN nesfatin-1对胃收缩幅度及频率的影响及潜在机制。方法:采用荧光金逆行追踪结合荧光免疫组化技术,观察LHA-PVN间nesfatin-1神经通路构成;采用细胞外放电记录,观察nesfatin-1对GD放点活动的影响;通过在体胃运动技术,观察nesfatin-1对清醒自由活动大鼠胃收缩幅度和频率的影响。结果:Nesfatin-1能够抑制GD-E神经元放电(1.97±0.12 Hz vs.1.15±0.07 Hz)促进GD-I神经元放电(1.74±0.10 Hz vs.3.04±0.18 Hz),H4928能够部分阻断nesfatin-1对GD神经元(GD-E:1.38±0.08 Hz,P0.05 vs.nesfatin-1;GD-I:2.49±0.15 Hz,P0.05 vs.nesfatin-1)的影响;PVN内微量注射nesfatin-1能够抑制大鼠胃运动,呈量效依赖关系;LHA和PVN间有nesfatin-1神经纤维联系;电刺激LHA后,GD神经元放电频率增加(GD-E:2.06±0.12 Hz vs.4.23±0.21 Hz,GD-I:1.61±0.09 Hz vs.4.83±0.25 Hz),预先向PVN注射抗NUCB2/nesfatin-1抗体后,GD-E神经元放电频率减弱(4.91±0.25 Hz vs.4.23±0.21 Hz),而GD-I神经元放电频率增强(4.15±0.18 Hz vs.4.83±0.25)。结论:PVN内nesfatin-1可调控大鼠GD神经元放电活动及胃运动,该效应受LHA调控。     

雌、雄大鼠去势对HPA轴分泌功能影响的比较

目的观察去势手术后雌、雄大鼠在低性激素状态下,下丘脑—垂体—肾上腺(HPA)轴功能的变化,证实性激素可对HPA轴的功能产生影响,并分析这种影响是否存在性别差异和时长效应。方法选用SPF级8周龄SD大鼠80只(雌雄各半),体重180~220 g,采用完全随机设计法,利用随机数字表将其分为雄性模型组、雄性对照组、雌性模型组、雌性对照组,每组20只大鼠,适应性饲养一周后行去势手术,于造模后第3周及第13周心脏取血,采用酶联免疫吸附法(ELISA)检测血清中促肾上腺皮质激素释放激素(CRH)、促肾上腺皮质激素(ACTH)、皮质酮(CORT)含量并进行统计分析。结果经检测造模第3周雄性模型组大鼠血清CRH、CORT含量显著低于对照组(P0.01),血清ACTH含量低于对照组(P0.05);雌性模型组大鼠血清CRH、CORT含量均低于对照组(P0.05),血清ACTH含量有下降趋势。造模第13周,雄性模型组大鼠血清CORT含量显著低于对照组(P0.01),其他激素含量变化不明显;雌性模型组大鼠血清CORT含量低于对照组(P0.05),其他激素含量变化不明显。雌、雄模型组大鼠造模后第13周与第3周组内相比CRH、ACTH、CORT的含量均无统计学差异(P0.05)。结论无论雌、雄,去势均可造成大鼠HPA轴功能的紊乱,表现为外周血CRH、ACTH、CORT水平下降,雄激素对雄鼠HPA轴的影响要大于雌激素对雌鼠的影响。推测雄激素可能更加有利于上述三种激素的产生。当雌、雄大鼠处于稳定的低性激素状态,其HPA轴分泌功能不随着大鼠周龄的增长而发生改变。     

Nesfatin‐1, corticotropin‐releasing hormone,thyrotropin‐releasing hormone,and neuronal histamine interact in the hypothalamus to regulate feeding behavior

Nesfatin‐1, corticotropin‐releasing hormone (CRH), thyrotropin‐releasing hormone (TRH), and hypothalamic neuronal histamine act as anorexigenics in the hypothalamus. We examined interactions among nesfatin‐1, CRH, TRH, and histamine in the regulation of feeding behavior in rodents. We investigated whether the anorectic effect of nesfatin‐1, α‐fluoromethyl histidine (FMH; a specific suicide inhibitor of histidine decarboxylase that depletes hypothalamic neuronal histamine), a CRH antagonist, or anti‐TRH antibody affects the anorectic effect of nesfatin‐1, whether nesfatin‐1 increases CRH and TRH contents and histamine turnover in the hypothalamus, and whether histamine increases nesfatin‐1 content in the hypothalamus. We also investigated whether nesfatin‐1 decreases food intake in mice with targeted disruption of the histamine H1 receptor (H1KO mice) and if the H1 receptor (H1‐R) co‐localizes in nesfatin‐1 neurons. Nesfatin‐1‐suppressed feeding was partially attenuated in rats administered with FMH, a CRH antagonist, or anti‐TRH antibody, and in H1KO mice. Nesfatin‐1 increased CRH and TRH levels and histamine turnover, whereas histamine increased nesfatin‐1 in the hypothalamus. Immunohistochemical analysis revealed H1‐R expression on nesfatin‐1 neurons in the paraventricular nucleus of the hypothalamus. These results indicate that CRH, TRH, and hypothalamic neuronal histamine mediate the suppressive effects of nesfatin‐1 on feeding behavior.     

Hypothalamic neuronal histamine mediates the thyrotropin-releasing hormone-induced suppression of food intake

We examined the involvement of thyrotropin-releasing hormone (TRH) and TRH type 1 and 2 receptors (TRH-R1 and TRH-R2, respectively) in the regulation of hypothalamic neuronal histamine. Infusion of 100 nmol TRH into the rat third cerebroventricle (3vt) significantly decreased food intake (p < 0.05) compared to controls infused with phosphate- buffered saline. This TRH-induced suppression of food intake was attenuated partially in histamine-depleted rats pre-treated with alpha-fluoromethylhistidine (a specific suicide inhibitor of histidine decarboxylase) and in mice with targeted disruption of histamine H1 receptors. Infusion of TRH into the 3vt increased histamine turnover as assessed by pargyline-induced accumulation of tele-methylhistamine (t-MH, a major metabolite of neuronal histamine in the brain) in the tuberomammillary nucleus (TMN), the paraventricular nucleus, and the ventromedial hypothalamic nucleus in rats. In addition, TRH-induced decrease of food intake and increase of histamine turnover were in a dose-dependent manner. Microinfusion of TRH into the TMN increased t-MH content, histidine decarboxylase (HDC) activity and expression of HDC mRNA in the TMN. Immunohistochemical analysis revealed that TRH-R2, but not TRH-R1, was expressed within the cell bodies of histaminergic neurons in the TMN of rats. These results indicate that hypothalamic neuronal histamine mediates the TRH-induced suppression of feeding behavior.     

Nesfatin-1 influences the excitability of glucosensing neurons in the hypothalamic nuclei and inhibits the food intake

Nesfatin-1 is a recently discovered neuropeptide that has been shown to decrease food intake after lateral, third, or fourth brain ventricle, cisterna magna administration, or PVN injection in ad libitum fed rats. With regards to the understanding of nesfatin-1 brain sites of action, additional microinjection studies will be necessary to define specific nuclei, in addition to the PVN, responsive to nesfatin-1 to get insight into the differential effects on food intake. In the present study, we evaluated nesfatin-1 action to modulate food intake response upon injection into the specific hypothalamic nuclei (PVN, LHA and VMN) in freely fed rats during the dark phase. We extend previous observations by showing that the nesfatin-1 (50 pmol) injected before the onset of the dark period significantly reduced the 1 to 5 h cumulative food intake in rats cannulated into the PVN, LHA, but not in rats cannulated into the VMN. Glucosensing neurons located in the hypothalamus are involved in glucoprivic feeding and homeostatic control of blood glucose. In order to shed light on the mechanisms by which nesfatin-1 exerts its satiety-promoting actions, we examined the effect of nesfatin-1 on the excitability of hypothalamic glucosensing neurons. Nesfatin-1 excited most of the glucose-inhibited (GI) neurons and inhibited most of the glucose-excited (GE) neurons in the PVN. Of 34 GI neurons in the LHA tested, inhibitory effects were seen in 70.6% (24/34) of GI neurons. The main effects were excitatory after intra-VMN administration of nesfatin-1 in GE neurons (27/35, 77.1%). Thus, our data clearly demonstrate that nesfatin-1 may exert at least a part of its physiological actions on the control of food intake as a direct result of its role in modulating the excitability of glucosensing neurons in the PVN, LHA and VMN.     

Hypothalamic neuronal histamine in genetically obese animals: its implication of leptin action in the brain

Leptin regulates feeding behavior and energy metabolism by affecting hypothalamic neuromodulators. The present study was designed to examine hypothalamic neuronal histamine, a recently identified mediator of leptin signaling in the brain, in genetic obese animals. Concentrations of hypothalamic histamine and tele-methylhistamine (t-MH), a major histamine metabolite, were significantly lower in obese (ob/ob) and diabetic (db/db) mice, and Zucker fatty (fa/fa) rats, leptin-deficient and leptin-receptor defective animals, respectively, relative to lean littermates (P < 0.05 for each). A bolus infusion of leptin (1.0 microg) into the lateral ventricle (ilvt) significantly elevated the turnover rate of hypothalamic neuronal histamine, as assessed by pargyline-induced accumulation of t-MH, in ob/ob mice compared with phosphate-buffered saline (PBS) infusions (P < 0.05). However, this same treatment did not affect hypothalamic histamine turnover in db/db mice. In agouti yellow (A(y)/a) mice, animals defective in pro-opiomelanocortin (POMC) signaling, normal levels of histamine, and t-MH were seen in the hypothalamus at 4 weeks of age when obesity had not yet developed. These amine levels in A(y)/a mice showed no change until 16 weeks of age, although the mice were remarkably obese by this time. Infusions of corticotropin releasing hormone (CRH), one of neuropeptide related to leptin signaling, into the third ventricle (i3vt) increased histamine turnover in the hypothalamus of Wistar King A rats (P < 0.05 versus PBS infusion). Infusion of neuropeptide Y (NPY) or alpha-melanocyte stimulating hormone (MSH), a POMC-derived peptide failed to increase histamine turnover. These results indicate that lowered activity of hypothalamic neuronal histamine in ob/ob and db/db mice, and fa/fa rats may be due to insufficiency of leptin action in the brains of these animals. These results also suggest that disruption of POMC signaling in A(y)/a mice may not impact on neuronal histamine. Moreover, CRH but neither POMC-derived peptide nor NPY may act as a signal to neuronal histamine downstream of the leptin signaling pathway.     

Endogenous GLP-1 acts on paraventricular nucleus to suppress feeding: Projection from nucleus tractus solitarius and activation of corticotropin-releasing hormone,nesfatin-1 and oxytocin neurons

Glucagon-like peptide-1 (GLP-1) receptor agonists have been used to treat type 2 diabetic patients and shown to reduce food intake and body weight. The anorexigenic effects of GLP-1 and GLP-1 receptor agonists are thought to be mediated primarily via the hypothalamic paraventricular nucleus (PVN). GLP-1, an intestinal hormone, is also localized in the nucleus tractus solitarius (NTS) of the brain stem. However, the role of endogenous GLP-1, particularly that in the NTS neurons, in feeding regulation remains to be established. The present study examined whether the NTS GLP-1 neurons project to PVN and whether the endogenous GLP-1 acts on PVN to restrict feeding. Intra-PVN injection of GLP-1 receptor antagonist exendin (9–39) increased food intake. Injection of retrograde tracer into PVN combined with immunohistochemistry for GLP-1 in NTS revealed direct projection of NTS GLP-1 neurons to PVN. Moreover, GLP-1 evoked Ca²⁺ signaling in single neurons isolated from PVN. The majority of GLP-1-responsive neurons were immunoreactive predominantly to corticotropin-releasing hormone (CRH) and nesfatin-1, and less frequently to oxytocin. These results indicate that endogenous GLP-1 targets PVN to restrict feeding behavior, in which the projection from NTS GLP-1 neurons and activation of CRH and nesfatin-1 neurons might be implicated. This study reveals a neuronal basis for the anorexigenic effect of endogenous GLP-1 in the brain.     

Hypothalamic neuronal histamine signaling in the estrogen deficiency-induced obesity

Menopause is one of the triggers that induce obesity. Estradiol (E2), corticotropin-releasing hormone (CRH), and hypothalamic neuronal histamine are anorexigenic substances within the hypothalamus. This study examined the interactions among E2, CRH, and histamine during the regulation of feeding behavior and obesity in rodents. Food intake was measured in rats after the treatment of E2, α-fluoromethyl histidine, a specific suicide inhibitor of histidine decarboxylase that depletes hypothalamic neuronal histamine, or CRH antagonist. We measured food intake and body weight in wild-type mice or mice with targeted disruption of the histamine receptors (H1-R) knockout (H1KO mice). Furthermore, we investigated CRH content and histamine turnover in the hypothalamus after the E2 treatment or ovariectomy (OVX). We used immunohistochemical staining for estrogen receptors (ERs) in the histamine neurons. The E2-induced suppression of feeding was partially attenuated in rats pre-treated with α-fluoromethyl histidine or CRH antagonist and in H1KO mice. E2 treatment increased CRH content and histamine turnover in the hypothalamus. OVX increased food intake and body weight, and decreased CRH content and histamine turnover in the hypothalamus. In addition, E2 replacement reversed the OVX-induced changes in food intake and body weight in wild-type mice but not in H1KO mice. Immunohistochemical analysis revealed ERs were expressed on histamine neurons and western blotting analysis and pre-absorption study confirmed the specificity of ER antiserum we used. These results indicate that CRH and hypothalamic neuronal histamine mediate the suppressive effects of E2 on feeding behavior and body weight.     

Brain‐derived neurotrophic factor,corticotropin‐releasing factor,and hypothalamic neuronal histamine interact to regulate feeding behavior

Brain‐derived neurotrophic factor (BDNF), corticotropin‐releasing factor (CRF), and hypothalamic neuronal histamine are anorexigenic substances within the hypothalamus. This study examined the interactions among BDNF, CRF, and histamine during the regulation of feeding behavior in rodents. Food intake was measured after treatment with BDNF, α‐fluoromethyl histidine (FMH; a specific suicide inhibitor of histidine decarboxylase that depletes hypothalamic neuronal histamine), or CRF antagonist. We measured food intake in wild‐type mice and mice with targeted disruption of the histamine H1 receptor (H1KO mice) after central BDNF infusion. Furthermore, we investigated CRF content and histamine turnover in the hypothalamus after BDNF treatment, and conversely, BDNF content in the hypothalamus after histamine treatment. We used immunohistochemical staining for histamine H1 receptors (H1‐R) in BDNF neurons. BDNF‐induced feeding suppression was partially attenuated in rats pre‐treated with FMH or a CRF antagonist, and in H1KO mice. BDNF treatment increased CRF content and histamine turnover in the hypothalamus. Histamine increased BDNF content in the hypothalamus. Immunohistochemical analysis revealed that H1‐Rs were expressed on BDNF neurons in the ventromedial nucleus of the hypothalamus. These results indicate that CRF and hypothalamic neuronal histamine mediate the suppressive effects of BDNF on feeding behavior and body weight.     

Regional distribution of the histamine metabolite, tele-methylimidazoleacetic acid, in rat brain: effects of pargyline and probenecid

Abstract: tele -Methylimidazoleacetic acid (t-MIAA), a major brain histamine metabolite, was measured in nine rat brain regions by a gas chromatography-mass spectrometric method that also measures the precursor amine, tele -methylhistamine (t-MH). The t-MIAA concentration of cerebellum, medulla-pons, midbrain, caudate nucleus, hypothalamus, frontal cortex, hippocampus, and thalamus varied 15-fold, hypothalamus showing the highest level (2.21 nmol/g) and cerebellum the lowest (0.15 nmol/ g). The concentrations of t-MIAA and t-MH were significantly correlated in all regions except midbrain, which had relatively more t-MIAA. Probenecid did not alter whole-brain t-MIAA levels. Treatment with pargyline, an inhibitor of monoamine oxidase, lowered the t-MIAA levels in all regions.     

Twenty-four hour rhythms of hypothalamic corticotropin-releasing hormone, thyrotropin-releasing hormone, growth hormone-releasing hormone and somatostatin in rats injected with Freund's adjuvant

The effect of Freund's adjuvant injection on 24-hour variation of hypothalamic corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH), GH-releasing hormone (GRH) and somatostatin levels was examined in adult rats kept under light between 0800 and 2000 h daily. Groups of rats receiving Freund's complete adjuvant or its vehicle 3 days before sacrifice were killed at six different time intervals throughout a 24-hour cycle. In the median eminence, adjuvant vehicle-injected rats exhibited significant 24-hour variations for the four hormones examined, with maxima at noon. These 24-hour rhythms were inhibited or suppressed by Freund's adjuvant injection. In the anterior hypothalamus of adjuvant vehicle-treated rats, CRH content peaked at 1600 h, while two peaks were found for TRH and GRH levels, i.e., at 2400-0400 h and 1600 h. Freund's adjuvant injection suppressed 24-hour rhythm of anterior hypothalamic CRH, TRH and GRH content and uncovered a peak in anterior hypothalamic somatostatin levels at 0400 h. In the medial hypothalamus of adjuvant vehicle-treated rats, significant 24-hour variations were detectable for TRH (peaks at 1600 and 2400 h) and somatostatin (peak at 2400 h) which disappeared after Freund's adjuvant injection. In the posterior hypothalamus of adjuvant vehicle-treated rats, two peaks were apparent for CRH, TRH and somatostatin levels, i.e. at 1600 h and 2400-0400 h, this hormonal profile remaining unmodified after Freund's adjuvant administration. The administration of the immunosuppressant drug cyclosporine (5 mg/kg, 5 days) impaired the depressing effect of Freund's adjuvant injection on CRH, TRH and somatostatin content in median eminence, but not that on GRH. In the anterior hypothalamus, cyclosporine generally prevented the effect of immunization on hormone levels an revealed a second maximum in TRH at 0400 h. Cyclosporine also restored 24-hour variations in TRH and somatostatin levels of medial hypothalamus of Freund's adjuvant-injected rats but was unable to modify them in the posterior hypothalamus. The results further support the existence of a significant effect of immune-mediated inflammatory response at an early phase after Freund's adjuvant injection on hypothalamic levels which was partially sensitive to immunosuppression by cyclosporine.     

CCK-8S activates c-Fos in a dose-dependent manner in nesfatin-1 immunoreactive neurons in the paraventricular nucleus of the hypothalamus and in the nucleus of the solitary tract of the brainstem

Recently, a new neuropeptide, named nesfatin-1, was discovered. It has been reported that nesfatin-1 inhibits food intake after injection into the third ventricle as well as intraperitoneal (ip) injection. Cholecystokinin (CCK) is well established to play a role in the regulation of food intake. The aim of the study was to examine whether CCK-8S injected ip modulates neuronal activity in nesfatin-1 immunoreactive (ir) neurons localized in the PVN and in the nucleus of the solitary tract (NTS). Additionally, tyrosine hydroxylase-immunoreactivity (TH-ir) in the PVN was determined to assess the distribution of TH-ir fibers in relation to nesfatin-1-ir. Non-fasted male Sprague-Dawley rats received 6 or 10 µg CCK-8S/kg or vehicle solution (0.15 M NaCl; n = 4 all groups) ip. The number of c-Fos-ir neurons was determined in the PVN, arcuate nucleus (ARC), and NTS. Double staining procedure for nesfatin-1 and c-Fos revealed that CCK-8S increased significantly and in a dose-dependent manner the number of c-Fos positive nesfatin-1-ir neurons in the PVN ( 4-fold and 7-fold) and NTS ( 9-fold and 26-fold). Triple staining in the PVN showed a dose-dependent neuronal activation of nesfatin-1 neurons that were colocalized with CRF and oxytocin. Double labeling against nesfatin-1 and TH revealed that nefatin-1-ir neurons were encircled in a network of TH-ir fibers in the PVN. No effect on the number of c-Fos-ir neurons was observed in the ARC. These results suggest that the effects of CCK on the HPA axis and on food intake may, at least in part, be mediated by nesfatin-1-ir neurons in the PVN.