Delivery of siRNA to the brain using a combination of nose-to-brain delivery and cell-penetrating peptide-modified nano-micelles

The potential for RNA-based agents to serve as effective therapeutics for central nerve systems (CNS) disorders has been successfully demonstrated in vitro. However, the blood–brain barrier limits the distribution of systemically administered therapeutics to the CNS, posing a major challenge for drug development aimed at combatting CNS disorders. Therefore, the development of effective strategies to enhance siRNA delivery to the brain is of great interest in clinical and pharmaceutical fields. To improve the efficiency of small interfering RNA (siRNA) delivery to the brain, we developed a nose-to-brain delivery system combined with cell-penetrating peptide (CPP) modified nano-micelles comprising polyethylene glycol–polycaprolactone (PEG–PCL) copolymers conjugated with the CPP, Tat (MPEG–PCL–Tat). In this study, we describe intranasal brain delivery of siRNA or dextran (Mw: 10,000 Da) as a model siRNA, by using MPEG–PCL–Tat. Intranasal delivery of dextran with MPEG–PCL–Tat improved brain delivery compared to intravenous delivery of dextran either with or without MPEG–PCL–Tat. We also studied the intranasal transfer of MPEG–PCL–Tat to the brain via the olfactory and trigeminal nerves, the putative pathways to the brain from the nasal cavity. We found that MPEG–PCL–Tat accelerated transport along the olfactory and trigeminal nerve pathway because of its high permeation across the nasal mucosa.     

Expression of type 1 vomeronasal receptors in the olfactory organ of the African lungfish,Protopterus dolloi

The vomeronasal organ is an olfactory organ found in amphibians and higher vertebrates. Type 1 vomeronasal receptors, one of the major olfactory receptors in vertebrates, are expressed in the vomeronasal organ in mammals. In amphibians and fish, they are expressed in the olfactory epithelium. The lungfish, which is the species of fish most closely related to amphibians, has a primitive vomeronasal organ: the recess epithelium. Expression of type 1 vomeronasal receptors has been reported in both the olfactory epithelium and the recess epithelium in three species of African lungfish and one species of South American lungfish. However, a previous study suggested that in the African lungfish Protopterus dolloi these receptors are expressed only in the olfactory epithelium. In this study, we identified 21 type 1 vomeronasal receptor genes in P. dolloi and examined the expression sites in the olfactory organ. In P. dolloi, most cells expressing the type 1 vomeronasal receptor were distributed in the olfactory epithelium, but a few were also found in the recess epithelium. This implies that the functions of the olfactory epithelium and the primitive vomeronasal organ are incompletely separated, and that all extant African and South American lungfish share this trait.     

嗅球和嗅束的断层解剖与MRI

目的：研究嗅球和嗅束的断面特点与MRI表现,为相关病变的影像学诊断和外科手术提供形态学依据。方法：选取国人成年尸头标本69例,经防腐和冷冻后,以电动断层带锯分别切制成连续横断层标本36例、矢状断层标本18例和冠状断层标本15例;采用SE序列,获取12例自愿者的头部1．5TMRI横、矢、冠状图像;利用3．0TMRI扫描仪,获取了10例自愿者的SE序列和3D-CISS序列头部断层图像;将上述连续断层标本和MRI图像相对照,观察、分析嗅球与嗅束的断面形态、MRI信号、位置及其毗邻关系等。结果：在冠状断面上,嗅球位于嗅束沟或直回与筛板之间,呈上方凹陷略扁的椭圆形;嗅束化于直同和嗅束沟下方,呈扁平的椭圆形。在矢状断面上,嗅球走行在颅前窝底直回下方,周围环绕以嗅池,其中上部嗅池较宽大。在横断面上,嗅束位于直回与眶回之间的嗅束沟内,视交叉的前外侧。MRI横断层、矢状断层和冠状断层图像均可显示嗅球、嗅束,其周围被嗅池环绕。结论：横断面、欠状断面和碰状断面均可清晰显示嗅球、嗅束的形态、位置和毗邻关系,其中以冠状断面为佳。     

Sex hormone binding globulin in the rat olfactory system

Ovarian steroids are known to act on the olfactory system. Their mode of action, however, is mostly unclear to date since nuclear receptors are lacking in sensory neurons. Here we used immunocytochemistry and RT-PCR to study expression and distribution of sex hormone binding globulin (SHBG) in the rat olfactory system. Single sensory cells in the olfactory mucosa and their projections in the olfactory bulb showed specific SHBG immunostaining as determined by double immunofluorescence with olfactory marker protein OMP. Larger groups of SHBG stained sensory cells occurred in the vomeronasal organ (VNO). A portion of the olfactory glomeruli in the accessory olfactory bulb showed large networks of SHBG positive nerve fibres. Some of the mitral cells showed SHBG immune fluorescence. RT-PCR revealed SHBG encoding mRNA in the olfactory mucosa, in the VNO and in the olfactory bulbs indicating intrinsic expression of the binding globulin. The VNO and its related projections within the limbic system are known to be sensitive to gonadal steroid hormones. We conclude that SHBG may be of functional importance for rapid effects of olfactory steroids on limbic functions including the control of reproductive behaviours through pheromones.     

Olfactory intensity-difference thresholds in rats and humans

Olfactory intensity difference limens were determined for 3 rats and 4 humans using a modified ascending method-of-limits procedure. A 0.01% solution of amyl acetate served as the standard stimulus. The mean Weber fraction ($\text{ΔI}\text{I}$) for human subjects (0.315) was significantly greater than that obtained for rats (0.041). The data provide the first direct comparisons of olfactory sensitivity in a macrosmatic and a microsmatic species.     

Factors influencing COVID-19 vaccination intention: The roles of vaccine knowledge,vaccine risk perception,and doctor-patient communication

ObjectiveThis study aims to investigate factors influencing COVID-19 vaccination intention in the United States.MethodsA cross-sectional survey was conducted with 800 respondents recruited from an online panel managed by a survey company. Path analysis was employed to examine the relationships between the study variables.ResultsFirst, perceived susceptibility to COVID-19 vaccine side effects was negatively associated with vaccination intention whereas perceived severity did not show any significant impact. Second, vaccine-related knowledge was not directly related to vaccination intention, but it had an indirect and positive effect on vaccination intention via decreasing perceived susceptibility. Third, doctor-patient communication strengthened the negative effect of vaccine knowledge on perceived susceptibility and severity.ConclusionThe results of this study offer insights on how to increase people’s vaccination intention and reduce their psychological concerns when making COVID-19 vaccine-related decisions.Practice implicationsGovernment agencies should actively promote the effectiveness and importance of vaccination, while addressing concerns about vaccine safety in the public; Health initiatives also need to enhance the level of knowledge about COVID-19 vaccines through various media channels; Doctors can start the conversations about COVID-19 vaccination with their patients at the point of care and/or via online communication platforms.     

Intranasal delivery of siRNA to the olfactory bulbs of mice via the olfactory nerve pathway

Adopting RNAi technology for targeted manipulation of gene expression in the central nervous system (CNS) will require delivery of RNAi constructs to the CNS followed by cellular transfection and induction of the RNAi machinery. Significant strides have been made in enhancing RNAi transfection and tailoring knockdown toward specific gene targets, however, delivery of the RNAi constructs to the CNS remains a significant challenge. One possible solution for targeting siRNA to the CNS is intranasal administration, which noninvasively delivers a variety of compounds to the CNS. The current study examined delivery of fluorescently labeled siRNA from the nasal cavity to the olfactory bulbs via the olfactory nerve pathway. siRNA was observed along the length of the olfactory nerve bundles, from the olfactory mucosa of the nasal cavity to the anterior regions of the olfactory bulbs. In the olfactory mucosa, labeled siRNA was found within the olfactory epithelium, Bowman's glands, and associated with blood vessels and bundles of olfactory nerves. In the olfactory bulbs, siRNA was observed in the olfactory nerve, glomerular and mitral cell layers. These results demonstrate a role of the olfactory nerve pathway in targeting siRNA to the olfactory bulbs. Additional investigations will be required to assess the distribution of intranasal siRNA to additional regions of the brain and explore the capacity of the delivered siRNA to silence gene expression in the CNS.     

Body signals, cardiac awareness, and the perception of time

Recent research suggests that our sense of time intervals in the range of seconds is directly related to activity in the insular cortex, which contains the primary sensory area for interoception. We therefore investigated whether performance in a duration reproduction task might correlate with individual interoceptive awareness and with measurable changes in autonomic activity during the task. Thirty-one healthy volunteers participated in an interoceptive (heartbeat) perception task and in repeated temporal reproduction trials using intervals of 8, 14, and 20 s duration while skin conductance levels and cardiac and respiratory periods were recorded. We observed progressive increases in cardiac periods and decreases in skin conductance level during the encoding and (less reliably) the reproduction of these intervals. Notably, individuals’ duration reproduction accuracy correlated positively both with the slope of cardiac slowing during the encoding intervals and with individual heartbeat perception scores. These results support the view that autonomic function and interoceptive awareness underpin our perception of time intervals in the range of seconds.     

嗅觉神经系统识别机制模型研究进展

相对人体其他的感觉系统,嗅觉神经系统是目前人们了解得较少的感觉神经系统.近来的科学研究表明,对复杂的嗅觉系统的研究有助于人们了解人体整个感觉系统的工作原理.本文以嗅觉神经系统的时空编码和解码机制研究为重点,介绍了近年来国际上广泛研究的、基于嗅觉生理解剖基础之上的嗅觉神经系统识别机制模型的研究工作.最后,结合我们目前的研究工作对嗅觉系统识别模型研究的发展进行了展望.     

Olfactory bulbectomy impairs the rat's radial-maze behavior

Previous studies had shown that transection of the lateral olfactory tracts and lesions of the septo-hippocampal system were similar in the deficits they engendered in nest building and food piling or hoarding by hamsters. The present investigation asked whether olfactory lesions would also produce deficits in radial-maze behavior like those associated with septo-hippocampal lesions. Radical olfactory bulbectomy led to a marked deterioration in preoperatively trained behavior in an 8-arm radial maze. The behavioral changes resembled those resulting from septo-hippocampal lesions in three ways: (1) There were fewer choices of adjacent arms and more choices of more distant arms. (2) Choice accuracy as a function of successive choices within a trial declined more rapidly. (3) The probability of repeating choice sequences was abnormally high. Earlier studies had shown that the rat does not require olfactory cues to perform efficiently in radial mazes. It therefore seems likely that the deficits described here resulted from the disruption of interconnections between the olfactory and septo-hippocampal systems rather than from the loss of olfactory sensitivity.     

Roles of the vomeronasal and olfactory systems in prey attack and feeding in adult garter snakes

Adult garter snakes preoperatively responded with more attacks and higher tongue-flick rates to earthworm extract soaked cotton swabs than to distilled water soaked swabs. Snakes with vomeronasal nerve lesions (N=6) failed to differentially respond to earthworm extract or to eat earthworm bits following surgery. Olfactory (N=6) and sham (N=6) nerve surgeries did not disrupt responding to swabs or earthworms.     

Attractive properties of sexual pheromones in mice: innate or learned?

It is generally assumed that chemical signals (sexual pheromones) constitute the primary stimulus for sexual attraction in many mammals. However, it is unclear whether these pheromones are volatile or nonvolatile and which sensory systems are involved in their detection (vomeronasal and/or olfactory). Moreover, it has been demonstrated that experience influences the behavioral response to sexual pheromones and the sensory systems implicated. In order to clarify this issue, the attractive properties of volatile and nonvolatile components of the male-soiled bedding have been analyzed in female mice that had no previous experience with adult male-derived chemical signals (chemically na?ve females) using two-choice preference tests. The results indicate that some nonvolatile male-derived substances exert an innate attraction to females, but volatiles derived from male-soiled bedding do not attract chemically nai;ve females. Therefore, the primary attractive sexual pheromone includes a nonvolatile compound (e.g. major urinary proteins, MUPs). On the other hand, male-derived volatiles become attractive to females because of repeated exposure to male-soiled bedding. This represents a Pavlovian-like associative learning in which previously neutral volatiles (very likely odorants) acquire attractive properties by association with the nonvolatile, innately attractive pheromone(s). These findings indicate that not only the sexual but also the 'chemical' experience (previous experience with sexual pheromones) has to be taken into account to interpret the role of chemicals as releaser or primer pheromones. The sensory systems involved in the detection of these stimuli and the neural basis of the odor-pheromone association are discussed.     

Olfactory sensory neurons in the sea lamprey display polymorphisms

The sea lamprey (Petromyzon marinus) is an ancient jawless fish phyletically removed from modern (teleost) fishes. It is an excellent organism in the study of olfaction due to its accessible olfactory pathway, which is susceptible to manipulation, and its important location in the evolution of vertebrates. There are many similarities in the olfactory systems of all fishes, and they also share characteristics with the olfactory system of mammals. Teleost fishes lack the distinctive vomeronasal organ of mammals; rather all odours are processed initially by olfactory sensory neurons (OSNs) of three morphotypes within the olfactory epithelium. We sought to identify olfactory sensory neuron polymorphisms in the sea lamprey. Using retrograde tracing with dyes injected into the olfactory bulb, we identified three morphotypes which are highly similar to those found in teleosts. This study provides the first evidence of morphotypes in the sea lamprey peripheral olfactory organ, and indicates that olfactory sensory neuron polymorphism may be a trait highly conserved throughout vertebrate evolution.     

Partner preference in male hamsters: steroids, sexual experience and chemosensory cues

This study investigated the effects of gonadal steroids on sexual motivation in male Syrian hamsters, using partner preference as a model. Male hamsters were assigned to 5 groups: control (n=4), Intact-->Orchx (n=8), Orchx-->Orchx+T (n=7), olfactory bulbectomy (BulbX, n=5), and vomeronasal organ lesion (VnoX, n=8). Each male was tested for partner preference before and after sexual experience. Unlike rats, sexually-inexperienced gonad-intact male hamsters preferred the receptive female to a stimulus male. However, sexual experience did not enhance preference for the stimulus female. Castration (Orchx) reduced sexual motivation: Orchx males showed no significant preference for the stimulus female. Subsequently, intact males were castrated (Intact-->Orchx) and Orchx males received a testosterone implant (Orchx-->Orchx+T) to determine the time course of gonadal hormones on partner preference and mating behavior. Partner preference changed significantly in both groups within 6 weeks. In Intact-->Orchx males, preference for the stimulus female decreased while Orchx-->Orchx+T males increased their preference for the stimulus female. However, significant changes in mating behavior preceded the alterations in partner preference. Chemosensory cues are also important for partner preference. After BulbX, preference for the stimulus female significantly decreased. However, VnoX failed to block partner preference. These results show that partner preference may be even more dependent on testosterone than is sexual behavior. Furthermore, while chemosensory cues are essential for sexual motivation, the vomeronasal organ is not required for partner preference.     

Olfactory bulbectomy depresses ultrasound production and scent marking by female hamsters

Female hamsters were observed for rates of ultrasound production, vaginal marking and flank marking before and after bilateral olfactory bulbectomy, unilateral bulbectomy or sham operations. Unilaterally bulbectomized and sham-operated subjects maintained preoperative levels of each behavior. In contrast, females with bilateral olfactory bulbectomies showed consistent decreases in rates of vocalization and scent marking. These results emphasize the dependence on an intact olfactory system of several courtship or agonistic behaviors that affect hamster reproduction by functioning as noncontact communications. Together with the results of previous studies suggesting that lordosis by female hamsters is unaffected by olfactory bulbectomy, these data also suggest differences in the brain and sensory mechanisms that control distinct types of reproductive behavior.     

Localization of sex hormone binding globulin in the rat vomeronasal organ

Volatile and non-volatile derivates of gonadal steroids are known to act as pheromones in many mammalian species. Pheromones have multiple effects on the brain via the olfactory system. Their primary port of entry seems to be the vomeronasal organ (VNO) but the underlying cellular and molecular mechanisms are unclear so far. Recently we localized sex hormone binding globulin (SHBG) in both the main and the accessory olfactory system of rat with immunocytochemistry and RT-PCR. The accessory olfactory system consisting of VNO and accessory olfactory bulb showed high expression of SHBG.In the present paper we studied SHBG expression in the VNO in greater detail. In semithin sections we found SHBG immunostaining in the perinuclear cytoplasm of some of the sensory neurons, in sensory cilia and in their axons. A portion of the basal cells and some of the goblet cells in the non-sensory epithelium showed intense SHBG staining. SHBG was abundant in exocrine cells of the vomeronasal glands, perhaps compartimentalized in secretory vesicles. In situ hybridization revealed specific signals in sensory and non-sensory cells of the VNO. Our findings indicate that SHBG expressed in the VNO may be liberated into nasal secretions to bind aerosolic steroids. SHBG in sensory cells may be involved in signaling actions of pheromones.     

生物嗅觉神经系统模型的模拟与分析

研究生物嗅觉神经系统模型,有助于更好地了解嗅觉机理和嗅神经的放电模式.本研究分析了K系列嗅觉神经系统模型的拓扑结构、数学基础的发展和应用,对该系列模型中的KⅢ模型进行了数值模拟及时域,频域和时频域分析;概述了K系列模型的发展和应用.由结果看出,KⅢ网络模型可以很好地模拟嗅觉神经系统的电活动.     

Immunohistochemical analysis of the development of olfactory organs in two species of turtles Pelodiscus sinensis and Mauremys reevesii

The nasal cavity of turtles is composed of the upper and lower chambers, lined by the upper and lower chamber epithelia, respectively. In many turtles including the Reeve’s turtle Mauremys reevesii, the upper chamber epithelium contains ciliated olfactory receptor neurons (ORNs) and the lower chamber epithelium contains microvillous ORNs. However, in the olfactory organ of the Chinese soft-shelled turtle Pelodiscus sinensis, both the upper and lower chamber epithelia contain ciliated ORNs. In the present study, we immunohistochemically examined the developmental process of olfactory organs in soft-shelled turtle and the Reeve’s turtle to clarify the developmental origins of the lower chamber epithelium in these turtles. Obtained data indicate that olfactory organs of these turtles have identical origin and follow similar process of development, suggesting that, in the lower chamber epithelium of the nasal cavity, ciliated ORNs differentiate in soft-shelled turtle whereas microvillous ORNs differentiate in the Reeve’s turtle.