Response of glucose-responsive ventromedial hypothalamic neurons to scrotal and preoptic thermal stimulation in rats

Almost all ventromedial hypothalamic (VMH) neurons facilitated by electro-osmotic application of glucose responded to scrotal thermal stimulation. On the other hand, only 50% of neurons which did not respond to glucose responded to the thermal stimulation. The VMH neurons facilitated or inhibited by scrotal warming were mostly facilitated or inhibited by preoptic warming, respectively. These results suggest that thermal signals from scrotal skin and preoptic area were conveyed to VMH neurons, especially to glucose-responsive ones, and could influence feeding control.     

Ultrasonographic assessment of human skeletal muscle size

The measurement of human muscle size is essential when assessing the effects of training, disuse and ageing. The considered gold standard for cross-sectional area measurements of muscle size is magnetic resonance imaging (MRI). However, MRI is costly and often inaccessible. The aim of the present study was to test the reproducibility and validity of a more accessible alternative method using ultrasonography (ULT). We examined the cross-sectional areas in the vastus lateralis muscle of six individuals. Axial-plane ULT scans were taken at given levels along the entire muscle length. The ULT scanning was repeated on different days (reliability) and validated against MRI-based measurements. Mean intraclass correlation coefficients were 0.998 for the reliability of ULT and 0.999 for the validity of ULT against MRI. The coefficient of variation values for cross-sectional area measurements assessed by six different experimenters were 2.1% and 0.8% for images obtained with ULT and MRI, respectively. The ULT method is a valid and reliable alternative tool for assessing cross-sectional areas of large individual human muscles. The present findings justify the application of the ULT method for the detection of changes throughout large muscles in response to training, disuse or as a consequence of sarcopenia.     

Effects of carbon dioxide on preoptic thermosensitive neurons in vitro

Effects of carbon dioxide (CO₂) on the firing rates of preoptic thermosensitive neurons were examined in rat brain slice preparations. The perfusing medium was saturated with gas mixtures consisting of 90% O₂ and one of various concentrations (5%, 6.3%, 7.5%, and 10%) of CO₂ balanced with N₂. The medium containing 5% CO₂ was used as control. Most preoptic neurons were inhibited during application of a high CO₂ medium. An excitatory effect of CO₂ on a small number of neurons was also significant, although this was weak and transient compared to the inhibitory effect. Thermosensitivities of the neurons did not correlate with their CO₂ sensitivities. The influence of CO₂ tended to be more evident at higher temperatures. We conclude that the direct effect of CO₂ on PO thermosensitive neurons as well as on thermally insensitive neurons is mainly inhibitory.     

Ventrolateral medullary neurons projecting to the medial preoptic/anterior hypothalamic area through the medial forebrain bundle: an electrophysiological study in the rat

Summary A total of 152 ventrolateral medullary neurons was antidromically stimulated from both the medial preoptic/anterior hypothalamic area (MPOAH) and the medial forebrain bundle (MFB) in urethane anesthetized rats. These neurons were located primarily dorsal to the lateral reticular nucleus and could be readily classified in at least two groups, type I and type II cells on the basis of electrophysiological properties. The action potentials of type I cells had a shorter duration, and their conduction velocities ranged from 0.45 to 3.1 m/s. By contrast, type II cells, most predominantly observed, were characterized by a longer duration and an unusual shape of their action potential, and the antidromic propagation into the somatodendritic complex was often blocked. The conduction velocity (mean = 0.21 m/s) and absolute refractory period (mean = 2.63 ms) of type II cells are consistent with them having fine non-myelinated axons. Injection of 6-hydroxydopamine (6-OHDA), but not 5,7-dihydroxytryptamine, directly into the MFB blocked antidromic responses of 57% of type II cells tested. The residual type II cells whose antidromic responses were not affected by 6-OHDA were located significantly rostral to the 6-OHDA sensitive cells. Neither antidromic response of type I cells tested, on the other hand, was affected by 6-OHDA. The majority of type I cells were dramatically activated by noxious pinches of the tail, whereas the noxious stimuli produced no detectable change in the firing of type II cells. These data demonstrate that ventrolateral medullary neurons projecting to the MPOAH through the MFB are comprised of at least three distinct populations: 6-OHDA resistant fast conducting cells with somatic afferents, 6-OHDA sensitive and resistant slow conducting cells.     

The topical organization of the afferents to the caudatoputamen of the rat. A horseradish peroxidase study

The aim of the present study was to assess (1) whether the various brain areas known to send projections to the neostriatum of the rat (neocortex, thalamus, substantia nigra, ventral tegmental area and dorsal raphe nucleus) project to all parts of this structure, and (2) whether the subcortical projections show a topical organization. For these purposes, small deposits of horseradish peroxidase were delivered by iontophoretic application, so that the whole extent of the caudatoputamen could be covered in a total of 40 rats.Labeled cortical cells were present mainly in lamina V, and showed a roughly topographical organization. Small numbers of labelled cells were observed in the basal nucleus of the amygdala after injections into the dorsal and central parts of the caudatoputamen. The cells of origin of thalamic afferents to the neostriatum were found not only in the intralaminar nuclei, but also in various other anterior, ‘midline’, and posterior nuclei (e.g. the medial part of the medial geniculate body). In the thalamostriatal projection a topical organization was demonstrated, consisting of oblique thalamic zones, which cross the borders of several thalamic nuclei and project to different parts of the neostriatum. In the substantia nigra and ventral tegmental area many retrogradely labelled cells were present. This nigrostriatal projection appears to be organized along an oblique longitudinal neostriatal axis. The nucleus raphes dorsalis was labelled most abundantly after caudal and ventrolateral injections into the caudatoputamen.It is concluded that, despite the homogeneous cytoarchitectonic structure of the caudatoputamen in the rat, this brain area is rather heterogeneous as regards its afferent connections. In fact each part of the neostriatum receives a specific and unique combination of afferents. The main changes in the input of the neostriatum appear to occur along an oblique longitudinal axis, from the most rostromedial and dorsal part to the caudolateral and ventral part. Such a topographical organization suggests that the neostriatum is likely to be involved in very complex integrative functions involving several brain areas.     

Injection of substance P (SP) N-terminal fragment SP(1-7) into the ventral tegmental area modulates the levels of nucleus accumbens dopamine and dihydroxyphenylacetic acid in male rats during morphine withdrawal

The biologically active substance P (SP) N-terminal metabolite SP_1–7 has been reported to modulate several neural processes such as learning, locomotor activity and reaction to opioid withdrawal. Although all these processes are believed to be associated with dopaminergic transmission no evidence of an interaction between SP_1–7 and dopamine in the case of morphine withdrawal has so far been reported. Therefore, in this work we applied in vivo microdialysis to investigate the effect of SP_1–7 injection into the ventral tegmental area on dopamine release in nucleus accumbens of male rats during naloxone precipitated morphine withdrawal. The result showed that the heptapeptide enhances dopamine release and also elevates the level of the dopamine metabolite dihydroxyphenylacetic acid in this brain area. It was suggested that the observed action of the SP fragment on the dopamine system represents the underlying mechanism for a previously observed ability of SP_1–7 to counteract the aversion response to morphine withdrawal.     

Projections from the ventral tegmental area and mesencephalic raphe to the dorsal raphe nucleus in the rat

Summary The origins of the dopaminergic innervation of the rat dorsal raphe nucleus (NRD) have been investigated using a combination of fluorescent retrograde tracing and fluorescence histochemistry. Stereotaxic microinjections of True Blue were placed in the central, caudal and lateral portions of the NRD, and after 6–12 days survival the brains were processed for fluorescence histochemical detection of catecholamines. Retrogradely labeled neurons were searched for in the diencephalic A11 and A13 dopaminergic cell groups, substantia nigra, ventral tegmental area (VTA) and the linear, central superior and dorsal raphe nuclei. The various NRD injections consistently resulted in retrograde labeling of a small number of catecholamine-containing, presumed dopaminergic cell bodies, confined mainly to three regions: the VTA, the linear and central superior raphe nuclei and the NRD itself. The present findings indicate that not only dopaminergic neurons in the VTA but also the system of catecholamine-containing cells, extending dorsally and caudally from the VTA within the midline raphe area, project to the NRD. Although often similar in size, shape and distribution to the catecholaminergic neurons the majority of retrogradely labeled cells in these regions were, however, found to be non-catecholaminergic.Abbreviations 3 Principal oculomotor nucleus - 4 Trochlear nucleus - Aq Cerebral aqueduct - cp cerebral peduncle - cst cortico-spinal tract - dscp decussation of the superior cerebellar peduncle - DTg Dorsal tegmental nucleus - fr fasciculus retroflexus - IF Interfascicular nucleus - IP Interpeduncular nucleus - LL nucleus of the lateral lemniscus - ml medial lemniscus - mlf medial longitudinal fasciculus - mNV mesencephalic trigeminal nucleus - NLC Nucleus linearis caudalis - NLR Nucleus linearis rostralis - NRD Dorsal raphe nucleus - PAG Periaqueductal grey - PN Pontine nucleus - PRN Pontine raphe nucleus - R Red nucleus - RCS Nucleus raphe centralis superior - SN Substantia nigra - VTA Ventral tegmental area - VTg Ventral tegmental nucleus     

胰腺外科学分段的解剖学基础及其意义

目的：为胰腺外科学分段提供解剖学基础。方法：在６４具灌注标本和４具铸型标本上观察胰内动脉分布、吻合。结果：头由胰十二指肠上动脉和胰十二指肠下动脉供血；颈为一乏血管区；体和尾由胰背动脉、胰支、胰大动脉和胰尾动脉供血。结论：全部胰腺可分为左侧段和右侧段     

Movement-related potentials preceding voluntary movement are modulated by the mode of movement selection

In two experiments movement-related cortical potentials preceding voluntary movement were recorded. In experiment 1, subjects performed four motor tasks involving joystick movements. The four tasks differed in complexity (single vs sequential movements) and in the mode of movement selection, i.e., whether a movement or movement sequence was made in fixed or in self-determined directions. The choice of these tasks was based, firstly, on previous electrophysiological studies suggesting an effect of task-complexity on the amplitude of the readiness potential (RP) and, secondly, on previous positron emission tomography (PET) studies showing that activity of the supplementary motor area (SMA) is influenced by the mode of movement selection. The results show that, for single movements, RP amplitude is higher preceding freely selected movements than preceding movements in a fixed direction. In experiment 2 this effect was replicated using button presses instead of joystick movements. The results converge with PET evidence obtained in similar tasks and establish that the RP is modulated by the mode of movement selection. This modulation is probably related to differential involvement of the SMA.     

Impulse activity of individual sensorimotor cortex neurons in rabbits after microiontophoretic administration of antibodies against acid fibroblast growth factor

We studied the sensitivity of sensorimotor cortex neurons in rabbits to microiontophoretic administration of antibodies against acid fibroblast growth factor (anti-aFGF). Spontaneous activity and reaction of neurons to electrical stimulation of ‘feeding centers’ in the lateral hypothalamic area (LHA) were recorded. We analyzed impulse activity of 52 neurons in the sensorimotor cortex. It was shown that 14 neurons (25%) reacted to microiontophoresis of anti-aFGF (excitation and inhibition in 9 and 5 neurons, respectively). Microiontophoretic administration of anti-aFGF did not change the reaction (excitation or inhibition) of 27 neurons to electrical stimulation of LHA. Initially, 14 neurons did not response to LHA stimulation. After microiontophoretic administration of anti-aFGF, 6 of 14 neurons displayed pronounced reactions to electrical stimulation of LHA (excitation and inhibition in 2 and 4 neurons, respectively). These data suggest that aFGF plays an important physiological role in feeding motivations.