棕色田鼠雄性幼体不同发育期犁鼻器和副嗅球的组织结构

通过对出生后不同发育时期雄性棕色田鼠犁鼻器和副嗅球进行组织学观察, 探讨棕色田鼠出生后犁鼻器和副嗅球的发育规律。实验以出生后当天(0 日龄) , 5 日龄, 15 日龄, 25 日龄以及成年棕色田鼠为研究对象,副嗅球采用Pischinger 氏染色法染色, 犁鼻器用H. E. 染色法染色后进行组织学观察。结果显示, 棕色田鼠出生时, 犁鼻器和副嗅球就已具有成体的基本结构, 随着动物个体的发育, 犁鼻上皮逐渐增厚, 犁鼻管变长, 犁鼻上皮中神经元密度增加; 腺体逐渐增大, 犁鼻管腔填充物增多, 犁鼻管背外侧的静脉血管逐日增大, 管腔周围出现越来越多的血管; 副嗅球长宽都增加, 僧帽细胞层和颗粒细胞层逐渐增长, 各层细胞密度变化稍有不同;出生后15 日内, 僧帽细胞层细胞密度增加, 15 日龄以后又开始降低, 25 日龄及成体的僧帽细胞层细胞密度与5日龄的相似; 颗粒细胞层细胞密度持续增高。实验结果提示, 棕色田鼠5 日龄时, 犁鼻器和副嗅球已具有了完整的结构, 到25 日龄时可能达到了功能上的成熟。     

4种两栖爬行动物嗅器和犁鼻器的显微结构比较

用光镜观察了4种两栖爬行动物嗅器和犁鼻器的组织结构.结果显示,北方山溪鲵(Batrachuperus tibetanus)鼻囊内开始分化出犁鼻器,犁鼻器位于嗅器的腹外侧,但犁鼻器还不发达;隆肛蛙(Feirana quadranus)犁鼻器与嗅器虽然共同位于鼻囊内,但犁鼻器较为发达且其周围有发达的犁鼻腺,犁鼻器通过一细小管道与嗅器相通;秦岭蝮(Gloydius qinlingensis)和菜花烙铁头(Trimeresurus jerdonii)犁鼻腔与鼻腔已经完全分离形成两个独立的囊,而且鼻腔又进一步分化为嗅部与呼吸部.说明犁鼻器从有尾两栖动物开始出现,至无尾两栖类开始分化,到蛇类高度发达且成为一个独立器官.犁鼻器的形成是脊椎动物适应陆地生活的直接结果,是四足动物的特征之一.     

哺乳类两大嗅觉系统功能的研究进展

近年来对于嗅觉系统的研究已成为动物学研究的热点之一,本文通过对以往关于哺乳类两大嗅觉系统功能的研究进行总结和回顾,对目前犁鼻器系统(VOE-AOB)和主嗅觉系统(MOE-MOB)功能结论上的争议做了初步探讨。通过概括和总结,发现目前对两大嗅觉系统功能还存在争议,其原因可能有以下几点:以前的研究方法上可能有不完善之处;不同的研究采用的物种不同,结论上的争议也许与不同物种间存在种间差异有关;动物的社会经验对研究结论可能也有一定影响。希望通过本文能进一步促进今后此方面的研究。     

Emerging views on the distinct but related roles of the main and accessory olfactory systems in responsiveness to chemosensory signals in mice

In rodents, the nasal cavity contains two separate chemosensory epithelia, the main olfactory epithelium, located in the posterior dorsal aspect of the nasal cavity, and the vomeronasal/accessory olfactory epithelium, located in a capsule in the anterior aspect of the ventral floor of the nasal cavity. Both the main and accessory olfactory systems play a role in detection of biologically relevant odors. The accessory olfactory system has been implicated in response to pheromones, while the main olfactory system is thought to be a general molecular analyzer capable of detecting subtle differences in molecular structure of volatile odorants. However, the role of the two systems in detection of biologically relevant chemical signals appears to be partially overlapping. Thus, while it is clear that the accessory olfactory system is responsive to putative pheromones, the main olfactory system can also respond to some pheromones. Conversely, while the main olfactory system can mediate recognition of differences in genetic makeup by smell, the vomeronasal organ (VNO) also appears to participate in recognition of chemosensory differences between genetically distinct individuals. The most salient feature of our review of the literature is that there are no general rules that allow classification of the accessory olfactory system as a pheromone detector and the main olfactory system as a detector of general odorants. Instead, each behavior must be considered within a specific behavioral context to determine the role of these two chemosensory systems. In each case, one system or the other (or both) participates in a specific behavioral or hormonal response.     

黑斑蛙嗅器和犁鼻器的组化及超微结构特征

嗅感受器主要感知外界环境中化学信号分子.本文采用银染、NADPH-组化染色和电镜技术来观察黑斑侧褶蛙(Petophylax nigromaculatus)的嗅器和犁鼻器的功能差异及细胞组成.银染法可对嗅上皮和犁鼻上皮的细胞进行分类及区分.其中,支持细胞胞核深染成黑色,嗅细胞胞核银染为花斑状.细胞计数显示,犁鼻上皮的嗅神经细胞含量百分比显著高于嗅上皮.组化结果显示,黑斑侧褶蛙嗅上皮和犁鼻上皮对NADPH-d表达模式差异显著,前者表达明显高于后者.电镜结果显示,黑斑侧褶蛙嗅上皮和犁鼻上皮的支持细胞由两种类型的细胞组成,分别为纤毛型和颗粒型支持细胞.     

Comparison of social interaction and neural activation in the main olfactory bulb and the accessory olfactory bulb between Microtus mandarinus and Microtus fortis

To gain insight into the function of AOB and MOB during different social interaction and in different vole species,the behaviors and neural activation of the olfactory bulbs in social interactions of mandarin voles Microtus mandarinus and reed voles Microtus fortis were compared in the present research.Mandarin voles spent significantly more time attacking and sniffing their opponents and sniffing sawdust than reed voles.During same sex encounters,mandarin voles attacked their opponents for a significantly ...     

Neurobiology of mammalian olfactory learning that occurs during sensitive periods

This review examines the organizational principles underlying olfactory learning in three specialized contexts that occur during sensitive periods of enhanced neural plasticity and emphasizes some of their common features. All three forms of olfactory learning are associated with neural changes in the olfactory bulb (OB) at the first stage of sensory processing. These changes require the association of the olfactory and somatosensory signals in the OB. They all depend on somatosensory stimulation -induced r...     

哺乳动物主要嗅觉系统和犁鼻系统信息识别的编码模式

哺乳动物具有两套嗅觉系统, 即主要嗅觉系统和犁鼻系统。前者对环境中的大多数挥发性化学物质进行识别, 后者对同种个体释放的信息素进行识别。本文从嗅觉感受器、嗅球、嗅球以上脑区三个水平综述了这两种嗅觉系统对化学信息识别的编码模式。犁鼻器用较窄的调谐识别信息素成分, 不同于嗅上皮用分类性合并受体的方式识别气味; 副嗅球以接受相同受体输入的肾丝球所在区域为单位整合信息, 而主嗅球通过对肾丝球模块的特异性合并编码信息; 在犁鼻系统, 信息素的信号更多地作用于下丘脑区域, 引起特定的行为和神经内分泌反应。而在主要嗅觉系统, 嗅皮层可能采用时间模式编码神经元群, 对气味的最终感受与脑的不同区域有关。犁鼻系统较主要嗅觉系统的编码简单, 可能与其执行的功能较少有关。     

Olfactory recognition memory

Olfactory recognition which occurs in the context pregnancy block by male pheromones is acquired with one-trial learning contingent on mating. A memory trace is established in the accessory bulb (AOB) and is represented by a gain in Gaba-ergic feedback inhibition of granule cells on excitatory glutaminergic mitral cells. This occurs in the sub-population of mitral cells that specifically respond to an individual male's pheromones, and is dependent on noradrenaline release at mating. Although relatively simple, the AOB has both structural and functional similarities with other trilaminar neural structures involved in learning, which suggests some evolutionary conservation of mechanisms subserving memory.     

The combined role of the main olfactory and vomeronasal systems in social communication in mammals

The main olfactory and the vomeronasal systems are the two systems by which most vertebrates detect chemosensory cues that mediate social behavior. Much research has focused on how one system or the other is critical for particular behaviors. This has lead to a vision of two distinct and complexly autonomous olfactory systems. A closer look at research over the past 30 years reveals a different picture however. These two seemingly distinct systems are much more integrated than previously thought. One novel set of chemosensory cues in particular (MHC Class I peptide ligands) can show us how both systems are capable of detecting the same chemosensory cues, through different mechanisms yet provide the same general information (genetic individuality). Future research will need to now focus on how two seemingly distinct chemosensory systems together detect pheromones and mediate social behaviors. Do these systems work independently, synergistically or competitively in communicating between individuals of the same species?     

The nose knows who's who: chemosensory individuality and mate recognition in mice

Individual recognition is an important component of behaviors, such as mate choice and maternal bonding that are vital for reproductive success. This article highlights recent developments in our understanding of the chemosensory cues and the neural pathways involved in individuality discrimination in rodents. There appear to be several types of chemosensory signal of individuality that are influenced by the highly polymorphic families of major histocompatibility complex (MHC) proteins or major urinary proteins (MUPs). Both have the capability of binding small molecules and may influence the individual profile of these chemosignals in biological fluids such as urine, skin secretions, or saliva. Moreover, these proteins, or peptides associated with them, can be taken up into the vomeronasal organ (VNO) where they can potentially interact directly with the vomeronasal receptors. This is particularly interesting given the expression of major histocompatibility complex Ib proteins by the V2R class of vomeronasal receptor and the highly selective responses of accessory olfactory bulb (AOB) mitral cells to strain identity. These findings are consistent with the role of the vomeronasal system in mediating individual discrimination that allows mate recognition in the context of the pregnancy block effect. This is hypothesized to involve a selective increase in the inhibitory control of mitral cells in the accessory olfactory bulb at the first level of processing of the vomeronasal stimulus.     

Neuropeptidergic regulation of affiliative behavior and social bonding in animals

Social relationships are essential for maintaining human mental health, yet little is known about the brain mechanisms involved in the development and maintenance of social bonds. Animal models are powerful tools for investigating the neurobiological mechanisms regulating the cognitive processes leading to the development of social relationships and for potentially extending our understanding of the human condition. In this review, we discuss the roles of the neuropeptides oxytocin and vasopressin in the regulation of social bonding as well as related social behaviors which culminate in the formation of social relationships in animal models. The formation of social bonds is a hierarchical process involving social motivation and approach, the processing of social stimuli and formation of social memories, and the social attachment itself. Oxytocin and vasopressin have been implicated in each of these processes. Specifically, these peptides facilitate social affiliation and parental nurturing behavior, are essential for social recognition in rodents, and are involved in the formation of selective mother-infant bonds in sheep and pair bonds in monogamous voles. The convergence of evidence from these animal studies makes oxytocin and vasopressin attractive candidates for the neural modulation of human social relationships as well as potential therapeutic targets for the treatment of psychiatric disorders associated with disruptions in social behavior, including autism.     

The Role of Inhibition in an Associative Memory Model of the Olfactory Bulb

The external plexiform layer is where theinteractions between the mitral (excitatory) and granule (inhibitory)cells of the olfactory bulb (OB) take place. Two outstanding features ofthese interactions are that they aredendrodendritic and that there seem to be nonebetween excitatory cells. The latter are usually credited with the role of forming Hebbian cell assemblies.Hence, it would seem that this structure lacks the necessaryingredients for an associative memory system.In this article we show that in spite of these two properties thissystem can serve as an associative memory. Our model incorporates theessential anatomical characteristics of the OB. The memories in oursystem, defined by Hebbian mitral assemblies, are activated viathe interactions with the inhibitory granule cells. The nonlinearityis introduced in our model via a sigmoid function that describesneurotransmitter release in reciprocal dendrodendritic synapses. Thecapacity (maximal number of odors that can be memorized) depends onthe sparseness of coding that is being used. For very low memoryactivities, the capacity grows as a fractional power of the number ofneurons. We validate the theoretical results by numericalsimulations. An interesting result of our model is that its capacityincreases as a function of the ratio of inhibitory to excitatorypopulations. This may provide an explanation for the dominance ofinhibitory cells in the olfactory bulb.     

Associative Memory and Segmentation in an Oscillatory Neural Model of the Olfactory Bulb

We discuss the first few stages of olfactory processing in the framework of a layered neural network. Its central component is an oscillatory associative memory, describing the external plexiform layer, that consists of inhibitory and excitatory neurons with dendrodendritic interactions. We explore the computational properties of this neural network and point out its possible functional role in the olfactory bulb. When receiving a complex input that is composed of several odors, the network segments it into its components. This is done in two stages. First, multiple odor input is preprocessed in the glomerular layer via a decorrelation mechanism that relies on temporal independence of odor sources. Second, as the recall process of a pattern consists of associative convergence to an oscillatory attractor, multiple inputs are identified by alternate dominance of memory patterns during different sniff cycles. This could explain how quick analysis of mixed odors is subserved by the rapid sniffing behavior of highly olfactory animals. When one of the odors is much stronger than the rest, the network converges onto it, thus displaying odor masking.     

Mating behavior induces changes of expression of Fos protein,plasma testosterone and androgen receptors in the accessory olfactory bulb (AOB) of the male mandarin vole Microtus mandarinus

In order to investigate the neuroendocrine mechanism of the mating behavior in the adult male mandarin voles Microtus mandarinus,the radioimmunoassay(RIA)and immunohistochemistry methods were used to investigate the differences in plasma testosterone(T)concentrations and distribution of T immunoreactive neurons(T-IRs),androgen receptor immunoreactive neurons(AR-IRs)and Fos protein immunoreactive neurons(Fos-IRs)in the accessory olfactory bulb(AOB)and the main olfactory bulb(MOB)following exposure to clean h...     

The "male effect" in sheep and goats: a review of the respective roles of the two olfactory systems

In sheep and goats, exposure of seasonally anestrous females to sexually active males results in activation of luteinizing hormone (LH) secretion and synchronized ovulation. This phenomenon is named "the male effect" and seems to constitute a major factor in the control of reproductive events. This effect depends mostly on olfactory cues and is largely mimicked by exposure to male fleece only. In sheep, preventing the vomeronasal organ (VNO) from functioning does not affect the female responses to male odor suggesting that, unlike in rodents, the accessory olfactory system does not play the major role in the perception of this pheromonal cue. Female responses also seem to depend on previous experience, an effect that is not common for pheromones and renders this model of special interest. The aim of the present report is to summarize our current knowledge concerning the "male effect" and in particular to clarify the respective roles of the two olfactory systems in the processes involved in this effect.     

Sexual differentiation of pheromone processing: Links to male-typical mating behavior and partner preference

Phoenix et al. (Phoenix, C., Goy, R., Gerall, A., Young, W., 1959. Organizing actions of prenatally administered testosterone propionate on the tissues mediating mating behavior in the female guinea pig. Endocrinology 65, 369–382.) were the first to propose an essential role of fetal testosterone exposure in the sexual differentiation of the capacity of mammals to display male-typical mating behavior. In one experiment control male and female guinea pigs as well as females given fetal testosterone actually showed equivalent levels of mounting behavior when gonadectomized and given ovarian steroids prior to adult tests with a stimulus female. This finding is discussed in the context of a recent, high-profile paper by Kimchi et al. (Kimchi, T., Xu, J., Dulac, C., 2007. A functional circuit underlying male sexual behaviour in the female mouse brain. Nature 448, 1009–1014.) arguing that female rodents possess the circuits that control the expression of male-typical mating behavior and that their function is normally suppressed in this sex by pheromonal inputs that are processed via the vomeronasal organ (VNO)-accessory olfactory nervous system. In another Phoenix et al. experiment, significantly more mounting behavior was observed in male guinea pigs and in females given fetal testosterone than in control females following adult gonadectomy and treatment with testosterone. Literature is reviewed that attempts to link sex differences in the anatomy and function of the accessory versus the main olfactory projections to the amygdala and hypothalamus to parallel sex differences in courtship behaviors, including sex partner preference, as well as the capacity to display mounting behavior.     

Comparison of Changes in GAD65 and GAD67 Immunoreactivity and Levels in the Gerbil Main Olfactory Bulb Induced by Transient Ischemia

In the present study, we investigated changes in glutamate decarboxylase 65 (GAD65) and GAD67 immunoreactivity and protein levels in the main olfactory bulb (MOB) after 5 min of transient forebrain ischemia in gerbils. GAD65 immunoreactivity in the sham-operated group was shown in neurons and neuropil except for the somata of granule cells. GAD65 immunoreactivity was increased in neurons in the external plexiform layer 60 days after ischemia, and in mitral cells 30 and 60 days after ischemia. GAD67 immunoreactivity in the sham-operated group was shown in periglomerular cells, neuron in the external plexiform layer and granule cells with neuropil. GAD67 immunoreactivity in periglomerular cells was increased 10, 45 and 60 days after ischemia. GAD67 immunoreactivity in neurons in the external plexiform layer was increased 10 and 15 days after ischemia. Mitral cells showed strong GAD67 immunoreactivity 10 days after ischemia. However, GAD67 immunoreactivity in the granule cells was not changed with time after ischemia. In Western blot analysis for GAD65 and GAD67 protein levels in the ischemic gerbil MOB, GAD65 level was not changed after ischemia; GAD67 level was increased 10 days after ischemia. These results suggest that transient ischemia causes changes in GAD65 and GAD67 immunoreactivity in the gerbil MOB, and this change may induce a malfunction in olfaction after an ischemic insult. Ki-Yeon Yoo and In Koo Hwang equally contributed to this article.     

初孵扬子鳄嗅球的超微结构研究

用电镜研究初孵扬子鳄的嗅球⒚嗅球的外颗粒层具有明、暗两种细胞⒚僧帽细胞层细胞排列紧密、规则,细胞之间无任何连接结构⒚内颗粒层见有 ３～５ 个细胞聚集成群,并有个别细胞出现胞质降解现象⒚除内颗粒层部分细胞外,其他各层细胞仍处于较幼稚阶段⒚胶质细胞已发生,外网状层中有薄薄的髓鞘出现⒚突触处于不同的发育阶段,大多为不对称型⒚     

Expression of Olfactory Receptors in Xenopus Oocytes

The rat olfactory epithelium and the amino acid-sensitive catfish olfactory system have been used as models to study the molecular mechanisms of olfactory transduction. Here we report the functional expression of rat and catfish olfactory receptors in Xenopus oocytes injected with mRNA isolated from the respective tissues. Application of odor ligands to injected oocytes, monitored by two-electrode voltage clamp, activates stimulus-dependent transmembrane currents that reverse direction at about the chloride equilibrium potential. The currents show characteristic secondary oscillations that are presumed to reflect underlying Ca2+ oscillations. Similar ligand-activated membrane currents induced in oocytes after injection of other mRNAs have been shown to be due to activation of endogenous Ca(2+)-activated chloride channels. In summary, our results demonstrate the usefulness of the Xenopus oocyte expression system for cloning and characterization of olfactory receptors in both fish and mammalian species.