Estrogen Receptor-A in Medial Preoptic Area Contributes to Sex Difference of Mice in Response to Sevoflurane Anesthesia

A growing number of studies have identified sex differences in response to general anesthesia;however,the underlying neural mechanisms are unclear.The medial preoptic area(MPA),an important sexually dimorphic structure and a critical hub for regulating consciousness transition,is enriched with estrogen receptor alpha(ERa),particularly in neuronal clusters that participate in regulating sleep.We found that male mice were more sensitive to sevoflurane.Pharmacological inhibition of ERαin the MPA abolished the sex differences in sevoflurane anesthesia,in particular by extending the induction time and facilitating emergence in males but not in females.Suppression of ERαin vitro inhibited GABAergic and glutamatergic neurons of the MPA in males but not in females.Furthermore,ERα.knockdown in GABAergic neurons of the male MPA was sufficient to eliminate sex differences during sevoflurane anesthesia.Collectively,MPA ERαpositively regulates the activity of MPA GABAergic neurons in males but not in females,which contributes to the sexdifference of mice in sevoflurane anesthesia.

The medial preoptic area and the regulation of parental behavior

The preoptic area （POA） is located in the most anterior part of the hypothalamus and is bordered dorsally by the anterior commissure and anteroventrally by the nucleus of the diagonal band of Broca[1]. Accumulating evidence from developmental neurobiology suggests, however, that the POA may be a separate entity from hypothalamus, and may actually be part of the basal telencephalon[2,3]. Both the hypothalamus and POA are highly complex and heterogeneous areas, containing multiple nuclei, each of which has specific fundamental functions for survival. Among these, the POA contains nuclei involved in the regulation of blood osmolality and temperature （the median preoptic nucleus）, sleep （the ventrolateral preoptic and suprachiasmatic nuclei）, ovulation （gonadotropin-releasing hormone neurons scattered mainly in the ventral part of the POA）, male sexual behavior （the medial preoptic nucleus）, and parental behavior （the central part of the medial POA, cMPOA）.

CHANGES IN FIRING RATE OF NORADRENERGIC NEURONS IN LOCUS COERULEUS FOLLOWING STIMULATION OF MEDIAL PREOPTIC AREA IN FEMALE RATS AT DIFFERENT STAGES OF THE ESTROUS CYCLE

Several studies showed that sex hormone receptors are in close relationship with classical neurotransmitter neurons especially catecholaminergic(CA) neurons. There are many gonadotrophin releasing hormone (GnRH) neurons in hypothalamus and the medial preoptic area (MPO). Electrical stimulation of MPO can cause a rise in secretion

氯化胆碱和蔗糖切片液制作的小鼠脑片下丘脑视前区神经元电生理特性的比较

目的比较不同切片液对小鼠下丘脑视前区(mPOA)脑片神经元电生理特性的影响。方法选取6~8周龄C57雌性小鼠,异氟烷麻醉后心脏灌注(通混合气950 mL/L O_(2),50 mL/L CO_(2))4℃氯化胆碱切片液或蔗糖切片液后取脑,振动切片机制备含mPOA脑区的冠状脑片,全细胞膜片钳记录mPOA电生理特性。结果采用蔗糖切片液制作的脑片mPOA神经元的内在兴奋性要优于氯化胆碱切片液,具体表现为细胞静息膜电位更超极化,动作电位幅度、不同电流刺激平均放电幅度、放电个数均高,半宽、基强度较小。而氯化胆碱切片液制作的脑片突触活性要更好,表现为兴奋性微小突触后电流频率高于蔗糖切片液制作脑片的细胞。结论蔗糖切片液和氯化胆碱切片液在保证细胞活性的情况下,蔗糖切片液更适合记录mPOA神经元的内在兴奋性,而氯化胆碱切片液更适合突触特性的记录。

动脉粥样硬化大鼠弓状核和视前内侧区神经元的形态变化

用雄性大鼠6只.一次性腹腔注射V_D60万单位/kg体重,存活35天(诱发动脉粥样硬化)后,取下丘脑作石蜡连续切片,用体视学方法分析了下丘脑弓状核和视前内侧区神经元的形态参数变化.结果发现:下丘脑区两个核团的神经元体积变小,数目增多,发生了明显的形态学改变.胸、腹王动脉弹性膜断裂,平滑肌细胞增生,形成明显的动脉粥样斑块.文内对其它形态参数也进行了比较和分析.

大鼠内侧杏仁核的性双形性和向内侧视前区直接投射的研究

本文将内侧杏仁核分为5个亚区：即前背亚区、前腹亚区、中背亚区、后背亚区和后腹亚区。细胞构筑定量分析结果表明;雄性大鼠内侧杏仁核的吻尾长度（1.440mm）、体积（0.6485mm3）、细胞总数（50421个）均显著大于雌性（吻尾长度为1.320mm，体积为0.5326mm3，细胞总数为43922个）。并且证明内侧杏仁核的5个亚区中.雄性大鼠后背亚区的吻尾长度（0.510mm）、体积（0.1519mm3）、细胞总数（13331个）都显著地大于雌性（吻尾长度为0.375mm、体积为0.0774mm3、细胞总数为8655个），而其它亚区无上述性别差异。另外，雄性大鼠内侧杏仁核及其后背亚区和后腹亚区的细胞密度小于雌性。上述性别差异均具有统计学意义。这些结果表明内侧杏仁核具有性双形性，且此性双形性主要表现在后背亚区。将HRP注入一侧内侧视前区，在同侧内侧杏仁核各亚区内标记细胞的平均数及其占内侧杏仁核内标记细胞总平均数的百分比为：后背亚区为107.4个，占58％;后瓜亚区为42.1个，占21.2％;前背亚区为16.毛个，占8.8％;前腹亚区为13.6个，占6.7％;中背亚区为9.6个，占5.3％。进一步提示后背亚区可能是内侧杏仁核与性功能有关的主要功能部位。

大鼠导水管周围灰质注射谷氨酸可使Barrington核神经元表达Fos

形态学研究已发现大鼠内侧视前区（ＭＰＯ）和导水管周围灰质（ＰＡＧ）发出大量轴突，投射至与排尿反射密切相关的Ｂａｒｒｉｎｇｔｏｎ 核。本研究试图通过注射谷氨酸钠到ＭＰＯ或ＰＡＧ后，观察Ｂａｒｒｉｎｇｔｏｎ 核内的Ｆｏｓ表达情况，来了解以上两通路的性质。将谷氨酸钠注射到ＭＰＯ后，只有少量Ｆｏｓ阳性神经元出现在Ｂａｒｒｉｎｇ－ｔｏｎ 核。而将谷氨酸钠注射到ＰＡＧ后，Ｂａｒｒｉｎｇｔｏｎ 核内出现大量的Ｆｏｓ阳性神经元。此结果提示，ＰＡＧ可能对大鼠脑桥排尿反射活动具有兴奋性调节作用。

内侧视前区微量注射NMDA对异丙酚睡眠作用的影响

目的 通过在内侧视前区(mPOA)微量注射NMDA,观察其对异丙酚睡眠作用的影响,探讨异丙酚睡眠作用机制。方法 SD大鼠42只,随机分为6组:NS组、2%二甲基亚砜(DMS0)组、异丙酚组、NMDA 10pmol组、NMDA 20pmol组、异丙酚+NMDA 20pmol组,记录并分析睡眠EEG变化。结果 微量注射异丙酚80 ng显著增加2 h内总睡眠时间,主要为延长非快动跟睡眠时期,缩短睡眠潜伏期。给予不同剂量NMDA时,2 h内总睡眠时间显著缩短,睡眠潜伏期延长。NMDA20pmol可拮抗异丙酚诱发的睡眠,主要缩短非快动眼睡眠时期,对快动眼睡眠无明显影响。结论 在mPOA微量注射NMDA可拮抗异丙酚的睡眠作用。

Kisspeptin regulates gonadotropin-releasing hormone secretion in gonadotropin-releasing hormone/enhanced green fluorescent protein transgenic rats

Kisspeptin is essential for activation of the hypothalamo-pituitary-gonadal axis. In this study, we established gonadotropin-releasing hormone/enhanced green fluorescent protein transgenic rats. Rats were injected with 1, 10, or 100 pM kisspeptin-10, a peptide derived from full-length kisspeptin, into the arcuate nucleus and medial preoptic area, and with the kJsspeptJn antagonist peptJde 234 into the lateral cerebral ventricle. The results of immunohistochemical staining revealed that pulsatile luteinizing hormone secretion was suppressed after injection of antagonist peptide 234 into the lateral cerebral ventricle, and a significant increase in luteinizing hormone level was observed after kisspeptin-10 injection into the arcuate nucleus and medial preoptic area. The results of an enzyme-linked immunosorbent assay showed that luteinizing hormone levels during the first hour of kisspeptin-10 infusion into the arcuate nucleus were significantly greater in the 100 pM kisspeptin-10 group than in the 10 pM kisspeptin-10 group. These findings indicate that kisspeptin directly promotes gonadotropin-releasing hormone secretion and luteinizing hormone release in gonadotropin-releasing hormone/enhanced green fluorescent protein transgenic rats. The arcuate nucleus is a key component of the kisspeptin-G protein-coupled receptor 54 signaling pathway underlying regulating luteinizing hormone pulse secretion.

大鼠视前内侧区的传入性神经纤维联系-HRP、EB、NY法研究

本文应用轴突逆行运输HRP、EB、NY研究大鼠视前内侧区的传入性神经纤维联系。所用三种示踪剂结果基本一致。结果为:在外侧隔核、外侧嗅束核、杏仁内侧核、下丘脑外侧区、下丘脑腹内侧核和乳头体前腹核内观察到密集的标记细胞。在杏仁皮质核、杏仁中央核、下丘脑室旁核、下丘脑后核、弓状核、乳头体上核、丘脑腹核尾侧部、未定带、腹侧被盖区、脚间核、中缝正中核和背核内观察到较多标记细胞。在中脑中央灰质腹侧部、兰斑核、外侧臂旁核及海马腹下角内观察到少数标记细胞。

大鼠视前内侧区的传出性神经纤维联系——WGA-HRP法研究

应用WGA-HRP顺行轴突运输研究大鼠视前内侧区传出性神经纤维投射。结果表明:视前内侧区的上行投射向嘴侧经斜角带进入外侧隔核;经髓纹进入缰核;经无名质进入杏仁前区及经终纹进入杏仁内侧核,另有标记纤维经内侧前脑束向外下行,经视束上方进入杏仁内侧核。下行投射经内侧前脑束进入下丘脑室旁核、外侧区、内侧核、后核、弓状核、乳头体前腹核和乳头体上核。继续向尾侧,标记纤维进入中脑腹侧背盖区,并投射到中缝正中核及中缝背核。

Activation of hypothalamic gono-like neurons in female rats during estrus

In mammals, gonadal function is controlled by the activity of hypothalamic gonadotropin-releasing hormone neurons, which control the secretion of adenohypophyseal and gonadal hormones. However, there are a number of unanswered questions in relation to gonadal function. It is currently unknown how erotogenic stimulation of the genitals influences the subpopulation of hypothalamic medial preoptic area neurons, antidromically identified as projecting to the median eminence at different periods of the estrous cycle. Additionally, the distinctiveness of hypothalamic medial preoptic area neurons, with respect to methods of feedback control by exogenous hormones, is also unknown. In this study, spontaneous discharges from individual neurons encountered within the medial preoptic area, gono-like neurons, were recorded extracellularly using glass microelectrodes. To confirm the cellular and histochemical properties of the recording units, antidromic stimulation was performed using a side-by-side bipolar stimulating electrode placed into the median eminence, alongside microiontophoretic injections of the conventional tracer, horseradish peroxidase. In addition, further immunohistochemical analyses were performed. Results showed that elevated gono-neuron activity was accompanied by increased background activity and greater responses to erotogenic stimuli during estrus. Application of clitoral traction stimulation resulted in increased activation of the gono-like neurons. This neuronal activity was noticeably inhibited by β-estradiol administration. Immunohistochemical analyses revealed the presence of gonadotropin-releasing hormone-reactive protein in hypothalamic cells in which electrophysiological recordings were taken. Thus, medial preoptic area neurons represent the subset of hypothalamic gonadotropin-releasing hormone neurons described from brain slices in vitro, and might serve as a useful physiological model to form the basis of future in vivo studies.

Studying Some Brain and Ovarian Morphological Traits in Diaglena spatulata Female Frogs Thriving in Conserved and Perturbed Habitats:A Preliminary Report and Its Implications for Amphibian Survival and Continuity

Amphibians are thought to be highly susceptible to perturbed environments. However, recent studies show that many of them are successful inhabitants of disturbed, fragmented habitats. The source of this resilience is yet unclear, but it may be the byproduct of having a robust phenotype and/or the result of phenotypic plasticity. We then assessed the contribution of each by evaluating cytological features of two brain nuclei that modulate reproductive behavior and of the ovary, using female specimens of the frog Diaglena spatulata prospering in conserved and disturbed areas of a tropical dry forest. Our results in the brain show that the medial amygdala, but not the preoptic area, had a reduced size in frogs collected in disturbed forests compared to specimens collected in conserved forests. Both brain nuclei displayed, however, neurons with a reduced size in frogs captured in disturbed forest patches. In contrast, ovarian cytological features were similar between groups. Our preliminary results lead us to propose that Diaglena spatulata female specimens might combine robust ovary and plastic brain’s phenotypic traits to confront disturbed environments. This, however, is still a working hypothetical framework that needs to be experimentally confirmed.

COMPARISON OF THE EFFECTS OF MEDIAL PRE OPTIC AREA AND VENTROMEDIAL NUCLEUS OF HYPOTHALAMUS ON THE DISCHARGES OF NORADRENERGIC NEURONS IN LOCUS COERULEUS IN FEMALE RATS AT DIFFERENT STAGES OF ESTROUS CYCLE

In the structure of brain the medial preoptic area (MPO) and ventromedial nucleus of hypothalamus (VMN)are the two parts where the estrogen receptors concentrate but have opposite effects on sexual behavior. Recently estrogen receptors have been known to be located in the locus coeruleus(LC), where noradrenergic(NE) fibres terminate in the hypothalamus arising from cell bodies. The discharge rate of NE-ergic neurons in LC can be increased by electrical stimulation of MPO in a female rat at estrus stage, and decreased at diestrus stage. These studies help us to infer that VMN might have some modulation influence on NE-ergic neurons in LC. In order to study the pattern activities

内侧视前区注射阿片受体激动剂对麻醉大鼠心血管和呼吸系统的影响

研究 μ型阿片受体激动剂羟甲芬太尼 （Ｏｈｍｅｆｅｎｔａｎｙｌ ＯＭＦ）及 δ阿片受体激动剂 Ｄ－Ｓｅｒ－２－Ｌｅｕ－Ｅｎｋｅｐｈａｌｉｎ-Ｔｈｒ （ＤＳＬＥ）对麻醉大鼠心血管和呼吸系统的影响。两药均用微量注射法注入内侧视前区（ｍｅｄｉａｌ ｐｒｅｏｐｔｉｃ ａｒｅａ， ＭＰＯ）。结果：注射 ５ ｎｍｏｌ ＯＭＦ可引起血压下降、心率减慢；注射 １０ ｎｍｏｌ ＯＭＦ引起血压、心率上升；注射δ型阿片受体激动剂 １０ ｎｍｏｌ ＤＳＬＥＴ引起血压下降，但对心率无明显影响。 ２０ ｎｍｏｌ纳洛酮可桔抗ＯＭＦ、ＤＳＬＥＴ的上述效应。上述剂量的ＯＭＦ、ＤＳＬＥＴ均对大鼠呼吸无明显影响。结论：结果提示，内侧视前区注射ＯＭＦ和ＤＳＬＥＴ引起的心血管效应是由阿片受体介导的，ＯＭＦ低剂量降压，高剂量升压；ＤＳＬＥＴ降压。