D1-like dopamine receptor density in nuclei involved in social behavior correlates with song in a context-dependent fashion in male European starlings

Research in songbirds shows that singing behavior is regulated by both brain areas involved in vocal behavior as well as those involved in social behavior. Interestingly, the precise role of these regions in song can vary as a function of the social, environmental and breeding context. To date, little is known about the neurotransmitters underlying such context-dependent regulation of song. Dopamine (DA) modulates highly motivated, goal-directed behaviors (including sexually motivated song) and emerging data implicate DA in the context-dependent regulation of singing behavior. This study was performed to begin to examine whether differences in DA receptors may underlie, in part, context-dependent differences in song production. We used autoradiographic procedures to label D1-like and D2-like DA receptors to examine the relationship between DA receptor density and singing behavior in multiple contexts in male European starlings (Sturnus vulgaris). Within a breeding context (when testosterone (T) was high), D1-like receptor density in the medial preoptic nucleus (POM) and midbrain central gray (GCt) negatively correlated with song used to attract a female. Additionally in this context, D1-like receptor density in POM, GCt, medial bed nucleus of the stria terminalis (BSTm), and lateral septum (LS) negatively correlated with song likely used to defend a nest box. In contrast, in a non-breeding context (when T was low), D1-like receptor density in POM and LS positively correlated with song used to maintain social flocks. No relationships were identified between song in any context and D2-like receptor densities. Differences in the brain regions and directional relationships between D1-like receptor binding and song suggest that dopaminergic systems play a region and context-specific role in song. These data also suggest that individual variation in singing behavior may, in part, be explained by individual differences in D1-like receptor density in brain regions implicated in social behavior.     

The role of the superior colliculus in predatory hunting

Combining the results of behavioral, neuronal immediate early gene activation, lesion and neuroanatomical experiments, we have presently investigated the role of the superior colliculus (SC) in predatory hunting. First, we have shown that insect hunting is associated with a characteristic large increase in Fos expression in the lateral part of the intermediate gray layer of the SC (SCig). Next, we have shown that animals with bilateral NMDA lesions of the lateral parts of the SC presented a significant delay in starting to chase the prey and longer periods engaged in other activities than predatory hunting. They also showed a clear deficit to orient themselves toward the moving prey and lost the stereotyped sequence of actions seen for capturing, holding and killing the prey. Our Phaseolus vulgaris-leucoagglutinin analysis revealed that the lateral SCig, besides providing the well-documented descending crossed pathway to premotor sites in brainstem and spinal cord, projects to a number of midbrain and diencephalic sites likely to influence key functions in the context of the predatory behavior, such as general levels of arousal, motivational level to hunt or forage, behavioral planning, appropriate selection of the basal ganglia motor plan to hunt, and motor output of the primary motor cortex. In contrast to the lateral SC lesions, medial SC lesions produced a small deficit in predatory hunting, and compared to what we have seen for the lateral SCig, the medial SCig has a very limited set of projections to thalamic sites related to the control of motor planning or motor output, and provides conspicuous inputs to brainstem sites involved in organizing a wide range of anti-predatory defensive responses. Overall, the present results served to clarify how the different functional domains in the SC may mediate the decision to pursue and hunt a prey or escape from a predator.     

失血性休克大鼠中脑导水管周围灰质腹外侧区一氧化氮合酶阳性神经元的变化

目的 观察失血性休克大鼠中脑导水管周围灰质（PAG）腹外侧区的一氧化氮合酶（NOS）阳性神经元的变化。方法 取雄性SD大鼠20只随机分成4组,即对照组（假手术组）、休克时组、休克45 min组和休克90 min组。对照组仅进行左股动脉插管而不放血;其他各组经左股动脉插管放血复制失血性休克模型。分别在休克时、休克45 min和休克90 min灌注固定后取脑干进行冰冻切片,行NADPH-d组化染色观察,并对各组PAG腹外侧区尾段的NOS阳性神经元和其背内侧NOS阳性突起密度进行比较。结果 PAG腹外侧区尾段的NOS阳性神经元密度的变化无统计学意义（P〉0.01）,但在失血性休克后NOS阳性神经元染色明显加深,其背内侧突起增密,变化有统计学意义（P〈0.01）。结论 大鼠PAG腹外侧区的NOS阳性神经元可能参与了失血性休克的发生发展,并且发挥着影响。     

一种基于BP网络的CT图像肝实质分割算法

提出一种基于BP网络分割CT图像序列中肝实质的方法。首先选取训练样本，提取样本图像中肝脏的纹理特征，作为输入向量，以对训练样本手工分割的结果作为导师信号，对BP神经网络进行训练，再用训练好的网络对CT图像序列中的肝实质进行分割，最后对分割后的结果进行三维区域生长及孔洞填充处理。实验结果表明：该方法能够有效的对肝脏纹理特征明显的CT图像序列进行分割，可用于CT图像序列的自动分割。     

Involvement of the raphé pallidus in the suppressive effect of preoptic warming on non-shivering thermogenesis in rats

Thermogenesis in the brown adipose tissue (BAT) is activated by the stimulation of the ventromedial hypothalamic nucleus (VMH). Local warming of the preoptic area (PO) suppresses this response. Injection of the GABA(A) receptor antagonist bicuculline into the caudal periaqueductal gray (cPAG), where excitatory neurons for BAT thermogenesis are located, did not influence the suppressive effect of PO warming. On the other hand, after bicuculline injection into the raphé pallidus, where excitatory neurons for BAT thermogenesis are also located, VMH stimulation produced BAT thermogenesis even during PO warming. The present results suggest that the inhibitory signal from the PO reaches the raphé pallidus and not the cPAG for the control of BAT thermogenesis.     

Analgesia and c-Fos expression in the periaqueductal gray induced by electroacupuncture at the Zusanli point in rats

The need to use anaesthetised or restrained animals in acupuncture research in laboratory animals may represent a confounding variable, since both anaesthesia and stress alter the pain threshold and the activity of pain-related brain areas. In the current study we assessed the participation of the periaqueductal gray (PAG) in electroacupuncture's (EA) analgesic effects applied to the Zusanli point (36S) under carefully controlled stress conditions. Repeated immobilisation protocols (6 days, 1 h/day and 13 days, 2 h/day) were used to diminish the influence of acute immobilisation stress on c-Fos expression and analgesia (tail-flick test) induced by electroacupuncture on the 36S point (EA36S). Animals submitted to immobilisation alone (IMMO) or to electroacupuncture (100 Hz, 2-4 V, faradic wave) on a non-point region (EANP) were compared with animals submitted to electroacupuncture on the 36S point. In animals not previously submitted to repeated immobilisation, electroacupuncture on the 36S point induced analgesia and c-Fos expression in the PAG was not different from that induced by electroacupuncture at a non-acupuncture point. In animals submitted to repeated immobilisation (repeated immobilisation for 6 days or repeated immobilisation for 13 days), however, electroacupuncture on point 36S led to higher levels of analgesia and c-Fos expression, specifically in the ventrolateral PAG (vlPAG), as compared with animal groups subjected only to immobilisation or to electroacupuncture on a non-point. Our findings endorse previous results, and point to a specific part of the PAG involved in the effects of electroacupuncture at the Zusanli point.     

Differential cholinergic activation of G proteins in rat and mouse brainstem: relevance for sleep and nociception

Murine models are increasingly used for investigations of sleep, yet no previous studies have characterized cholinergic activation of guanine nucleotide binding proteins (G proteins) in mouse brainstem nuclei known to regulate sleep. This study used in vitro [(35)S]guanylyl-5'-O-(gamma-thio)-triphosphate ([(35)S]GTPgammaS) autoradiography to test the hypothesis that muscarinic cholinergic receptors activate G proteins in C57BL/6J (B6) mouse brainstem. The nuclei studied are homologous to those known in rat and cat to modulate sleep and nociception. In B6 mouse, carbachol significantly increased specific binding of [(35)S]GTPgammaS in the pontine reticular nucleus, caudal part (79%); pontine reticular nucleus, oral part (131%); laterodorsal tegmental nucleus (56%); pedunculopontine tegmental nucleus (86%); dorsal raphe nucleus (53%); dorsal medial periaqueductal gray (54%); and ventrolateral periaqueductal gray (52%) when compared with basal binding. Carbachol-induced G protein activation was concentration-dependent and blocked by atropine, demonstrating mediation by muscarinic receptors. G protein activation by carbachol was heterogeneous across B6 mouse brainstem nuclei. Comparison of [(35)S]GTPgammaS binding between mouse and rat revealed different magnitudes of G protein activation in the pontine reticular formation. In the same pontine reticular formation area of B6 mouse where in vitro treatment with carbachol activates G proteins, in vivo microinjection of cholinomimetics causes a rapid eye movement sleep-like state. These data provide the first direct measurement of muscarinic receptor-activated G proteins in B6 mouse brainstem nuclei known in other species to regulate sleep.     

Identification of spinal neurons involved in the urethrogenital reflex in the female rat

The urethrogenital (UG) reflex is a spinal sexual reflex that consists of autonomic and somatic nerve activity and vaginal, uterine, and anal sphincter contractions. The UG reflex is under tonic descending inhibition by neurons in the region of the nucleus paragigantocellularis (nPGi). The location of spinal neurons activated by the UG reflex was examined in the female rat using the immediate early gene, c-fos. In addition, the descending inputs from the nPGi onto fos-activated neurons was examined using the anterograde tracer biotin dextran amine injected into the nPGi. The UG reflex resulted in a significant increase in fos-positive nuclei in segments T12-S1, compared with experimental controls in which the UG reflex was not activated. Spinal circuits involved in the UG reflex include neurons relaying afferent information from the pudendal sensory nerve, in the dorsal horn and medial cord of L5-S1. Efferent output includes preganglionic neurons located in the lateral gray of L5-S1 and lateral and medial gray of T13-L2. Spinal interneurons involved in the UG reflex were found close to the preganglionic neurons and in the dorsal horn and intermediate and medial gray of T12-S1. NPGi inputs were found primarily on the autonomic efferents and interneurons in the medial and intermediate gray. These studies demonstrate multisegmental spinal circuits activated with the UG reflex and demonstrate that the descending inhibition from the nPGi is by means of preganglionic and somatic efferents and spinal interneurons closely associated with the efferent output.     

Localized <Superscript>1</Superscript>H magnetic resonance spectroscopy in mainly cortical gray matter of patients with multiple sclerosis

The brain water fraction (R), the brain water transverse relaxation time (T2), the atrophy index (α) and the absolute concentration of the principal brain metabolites (NAA, Cho and Cr) were measured by localized proton magnetic resonance spectroscopy in the occipito-parietal cortex (mainly gray matter) of 15 relapsing-remitting (R-R) multiple sclerosis (MS) patients, 15 secondary progressive (SP) MS patients and 8 healthy subjects. Significantly lower values of N-acetylaspartate (NAA), creatine (Cr) and the NAA/Cr ratio in the occipito-parietal cortex were detected in SP MS patients than in R-R MS and control subjects (p < 0.01). Moreover, MS patients showed shorter T2 water relaxation times and reduced brain water fraction compared with controls. Higher atrophy indices were also detected in the mainly occipito-parietal gray matter of MS patients, particularly in those with the progressive form. These findings suggest that the pathological process in MS is not limited to either white matter lesions or normal-appearing white matter but extends into the cortical gray matter (occipito-parietal), particularly in the progressive form of the disease. This can involve changes in neural metabolism or neural shrinkage and neuron loss. The significant increase in atrophy indices could be the expression of the relatively higher cerebrospinal fluid signal from the occipito-parietal cortex, even in the absence of obvious cortical atrophy. Received: 18 January 2001, Received in revised form: 16 January 2002, Accepted: 29 January 2002     

Fos expression induced by warming the preoptic area in rats

The preoptic area (POA) occupies a crucial position among the structures participating in thermoregulation, but we know little about its efferent projections for controlling various effector responses. In this study, we used an immunohistochemical analysis of Fos expression during local warming of the preoptic area. To avoid the effects of anesthesia or stress, which are known to elicit Fos induction in various brain regions, we used a novel thermode specifically designed for chronic warming of discrete brain structures in freely moving rats. At an ambient temperature of 22 degrees C, local POA warming increased Fos immunoreactivity in the supraoptic nucleus (SON) and the periaqueductal gray matter (PAG). Exposure of animals to an ambient temperature of 5 degrees C induced Fos immunoreactivity in the magnocellular paraventricular nucleus (mPVN) and the dorsomedial region of the hypothalamus (DMH). Concurrent warming of the POA suppressed Fos expression in these areas. These findings suggest that thermal information from the preoptic area sends excitatory signals to the SON and the PAG, and inhibitory signals to the mPVN and the DMH.