室旁核在刺激肾神经传入纤维对血浆皮质醇浓度影响中的作用

本文在氯醛糖麻醉猫中探讨室旁核毁损前、后,电刺激肾神经传入纤维对血浆皮质醇浓度的影响。在动脉压力感受器完整猫中,刺激肾神经传入纤维对血浆皮质醇浓度无明显影响,但在动脉压力感受器去神经和迷走神经切断(SAD+VD)后,电刺激肾神经中枢端引起血浆皮质醇浓度升高。微量注射红藻氨酸毁损双侧室旁核后,可阻断刺激肾神经传入纤维引起的血浆皮质醇浓度升高,这些结果表明:动脉压力感受性反射可抑制刺激猫肾神经传入纤维引起的血浆皮质醇浓度升高;室旁核在刺激肾神经传入纤维引起的血浆皮质醇浓度升高效应中起重要作用。     

Locomotory activity in the extensor and flexor tibiae of the cockroach, Periplaneta americana

Electromyograms (EMGs) were recorded from the metathoracic extensor and flexor tibiae of cockroaches when the animals were: walking on a level surface, walking on a ball, or producing rhythmic leg movements while being restrained ventral surface upward. In the rapidly walking (> 2 steps/s) and restrained animals, there was reciprocity between EMGs from the extensor and flexor tibiae. In slowly walking (<-2 steps/s) animals there was a conspicuous overlap in the flexor and extensor EMGs. The overlap was due to an increase in duration in the activity of the flexor. In experiments in which distal portions of a limb were amputated, the overlap observed in slow walking was either reduced greatly or lost entirely. These results are in agreement with recent locomotory models which state that the motor output is produced by a central pattern generator but can be modified by peripheral sensory inputs.     

Spinal dorsal column afferent fiber composition in the pigeon: an electrophysiological investigation

Summary The spinal dorsal column of homing pigeons (Colomba livia) was investigated electrophysiologically by recording responses from individual afferent fibers at a high cervical level (segments C4-C5) to mechanical stimulation of wing skin and deep tissue. Of 157 afferent fibers 134 were cutaneous afferents. The remainder were afferents of deep receptors.Thirty of the cutaneous afferents were slowly adapting and 87 rapidly adapting (17 not identified). Rapidly adapting afferents were studied with regard to Pacinianlike characteristics (Herbst corpuscles in birds; vibration sensitive receptors). Of 43 rapidly adapting afferents 38 were classified as afferents of vibration sensitive Herbst corpuscles and 5 as non vibration sensitive rapidly adapting afferents; 44 afferents could not be studied sufficiently with regard to vibrational stimuli. The vibration sensitive Herbst corpuscle afferents had U-shaped vibrational tuning curves and responded best to vibration frequencies of 300 to 400 Hz. The 11 threshold for 300 Hz vibration ranged from 2 to 36 um. Herbst corpuscle afferents always showed strong phase coupling to the stimulus cycle.Afferents of deep receptors showed slowly adapting responses to firm pressure or movements of limbs and were classified as joint receptors. No muscle spindle afferents were encountered.Primary afferent fibers were identified in 89 cases (80 cutaneous and 9 deep), postsynaptic elements in 15 cases (11 cutaneous, 4 deep). Only slowly adapting responses were found in postsynaptic fibers.Abbreviations CV coefficient of variation - EI entrainment index - INTH interval histogram - PSTH peristimulus time histogram - RA rapidly adapting - SA slowly adapting     

电刺激肾神经传入纤维对肾水钠钾排出的影响

本文探讨肾神经传入纤维对肾排泄功能的影响及其机制。在戊巴比妥钠麻醉猫中,切除双侧颈动脉窦神经、主动脉神经和迷走神经(SAD+VD),电刺激肾神经传入纤维使动脉血压明显升高,去神经肾的尿量,排钠量显著增多,排钾量和肾小球滤过率不变。神经完好肾的排钠量显著增加,尿量、排钾量和肾小球滤过率均无显著变化。在刺激肾神经传入纤维时,将动脉血压控制在对照期血压水平,两侧肾的尿量、排钠量、排钾量显著减少;神经完好肾的肾小球滤过率减少,而去神经肾的肾小球滤过率无显著改变。脊髓横断不能消除神经完好肾上述肾排泄功能的改变,但可消除去神经肾排泄功能的改变。这些结果表明,在SAD+VD猫中,控制动脉血压不变时,刺激肾神经传入纤维可使有神经肾和去神经肾排尿、排钠和排钾减少。在神经完好肾中这些反应可在脊髓水平完成。     

NO和ANP对内皮素引起大鼠肾神经传入放电增加的阻抑作用

目的和方法：采用电生理学技术观察一氧化氮（NO）和心房钠尿肽（ANP）对肾动脉内注射内皮素（ET）所致麻醉大鼠肾神经传入放电（RANA）的影响。结果：①肾动脉内注射ET－1后平均动脉压（MAP）先有短暂的降低随后为较显著的持久增高,RANA明显增加;②肾动脉内分别注射NO前体L－Arg和ANP后,ET－1的上述效应即被阻抑。结论：肾动脉ET－1引起RANA明显增加,百此效应可被同一途径注射NO和ANP所消除。     

Electrical activity in the vagus nerves and some medullary nuclei in rats: Changes induced by endotoxin action and hyperthermia evoked by an increase in ambient temperatures

Acute experiments on rats showed that intraperitoneal administration of 5 μg/kg of a bacterial toxin (pyrogenal) increases the afferent impulsation frequency in the cervical segments of vagus nerves, VN (multifiber recording), and frequency of the multineuronal activity in the solitary tract nucleus (STN); these changes were observed during the whole period of recording (10–160 min following toxin injection). Enhancement of the efferent impulsation in the VN and neuronal activity in the dorsal nucleus of the vagus nerve (DNVN) could be observed only 120–130 min after toxin administration. Under these conditions rectal temperature in experimental animals was 1.5° higher than that in control rats throughout the period of recording. Following subdiaphragmatic vagotomy, the afferent impulsation frequency in the cervical VN decreased about four times and kept on decreasing during the whole period of registration. Pyrogenal introduction evoked no changes in the direction of reactions to vagotomy. Under these conditions, body temperature of these animals was 2.5°C higher than in control vagotomized rats by the final stage of recording. Animal heating in a chamber caused no changes in the afferent impulsation frequency and resulted in a decrease in the frequency of VN efferent discharges. Involvement of the VN in the maintenance of temperature homeostasis during fever induced by the endotoxin action and by hyperthermia due to a rise in ambient temperature is discussed. Neirofiziologiya/Neurophysiology, Vol. 32, No. 2, pp. 112–119, March–April, 2000.     

大鼠脊髓后角内神经降压素对一级传入C纤维突触前抑制效应的形态学证据(英文)

本研究的目的是为了揭示大鼠脊髓后角内的神经降压素是否对一级传入C纤维进行突触前调节,荧光显微镜下观察到,在脊髓Ⅰ－Ⅲ层内,和压素样免疫反应性（NTLI）的分布与来源于西非单豆素的同工凝集素Ⅰ－B4（Ⅰ－B）的结合位点到分布有部分重叠,在其聚集激光扫描显微镜下进一步观察显微镜下,在蛛网膜下腔注射辣椒素的大鼠脊髓后角浅层内,一些NTLI阳性终末与变性终末形成突触性和／或非突触性接触。以上结果表明,NT可通过轴轴突触和／或非突触性轴轴接触的一级传入C纤维的传入进行突触前抑制。此外,脊髓后角内还存在变性终末与含NTLI树突形成的轴树突触。     

Blunted Vagal Cocaine- and Amphetamine-Regulated Transcript Promotes Hyperphagia and Weight Gain

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Mapping the Effects of SI Cortex Stimulation on Somatosensory Relay Neurons in the Rat Thalamus: Direct Responses and Afferent Modulation

We have used single-unit recording techniques to map the spatial distribution of the primary somatosensory (SI) cortical influences on thalamic somatosensory relay nuclei in the rat. A total of 193 microelectrode penetrations were made to record single neurons in tracks through the medial and lateral ventroposterior (VPL and VPM), ventrolateral (VL), posterior (Po), and reticular (nRt) thalamic nuclei. Single units were classified according to their (1) location within the nuclei, (2) receptive fields, and (3) response to standardized microstimulation in deep layers of the SI cortical forepaw areas. The SI stimulation produced short-latency (1- to 7-msec) excitatory responses in different percentages of neurons recorded in the following thalamic nuclei: VPL, 42.0%; Po, 25.0%; nRt, 16.4%; VL, 13.6%; and VPM, 9.9%. Within the VPL, the highest proportion of responsive neurons was found in the anterior region. Although most of the VL region was unresponsive, the caudal subregion bordering the rostral VPL showed some responsiveness (13.6% of neurons). In general, the spatial pattern of corticothalamic influences appeared to reciprocate the known thalamocortical connection patterns, but with a heterogeneity that was unpredicted.

The same parameters of SI cortical stimulation were used in studies of corticofugal modulation of afferent transmission through the VPL thalamus. A condition—test (C-T) paradigm was implemented in which the cortical stimulation (C) was delivered at a range of time intervals before test (T) mechanical vibratory stimulation was applied to digit 4 of the contralateral forepaw. The time course of cortical effects was analyzed by measuring the averaged evoked unit responses of thalamic neurons to the T stimuli, and plotting them as a function of C-T intervals from 5 to 50 msec. Of the 20 VPL neurons tested during SI stimulation, the average response to T stimulation was decreased a mean of 36%, with the suppression peaking (at 49% inhibition of the afferent response) about 15 msec after the C stimulus. Considerable rostrocaudal variation was observed, however. Whereas neurons in the rostral VPL (near VL) were strongly inhibited (-69%), neurons in the middle and caudal VPL exhibited facilitations at long and short C-T intervals, respectively. This study establishes a specific projection system from the forepaw region of SI cortex to different subregions of the VPL thalamus, producing specific temporal patterns of sensory modulation.     

Response properties of mouse trigeminal ganglion neurons

We used controlled whisker deflections to examine the response properties of 208 primary afferent neurons in the trigeminal ganglion of adult mice. Proportions of rapidly adapting (RA, 47%) and slowly adapting (SA, 53%) neurons were equivalent, and most cells had low or no spontaneous activity. We quantified angular tuning and sensitivity to deflection amplitude and velocity. Both RA and SA units fired more frequently to larger deflections and faster deflections, but RA units were more sensitive to differences in velocity whereas SA units were more sensitive to deflection amplitudes. Almost all neurons were tuned for deflection angle, and the average response to the maximally effective direction was more than fourfold greater than the average response in the opposite direction; SA units were more tuned than RA units. Responses of primary afferent whisker-responsive neurons are qualitatively similar to those of the rat. However, average firing rates of both RA and SA neurons in the mouse are less sensitive to differences in deflection velocity, and RA units, unlike those in the rat, display amplitude sensitivity. Subtle observed differences between mice and rats may reflect greater mechanical compliance in mice of the whisker hairs and of the tissue in which they are embedded.