Lateralized rewarding brain stimulation affects forepaw preference in rats

Rats trained to reach for food pellets into a narrow tubular feeder consistently prefer to perform this stereotype instrumental movement with either the left or right forepaw. In 16 rats with established handedness electrodes were implanted into both lateral hypothalami. The animals were rewarded by intracranial self stimulation (ICSS, 300 msec, 50 Hz, 20-60 microA) for reaching into a modified feeder for a plastic ball operandum, the movement of which between the bottom and entrance of the feeder was monitored by mechanical contacts. The rats readily continued to reach when ICSS was delivered immediately after the photoelectrically detected reach or after the displacement of the operandum. Most rats learned in a single session to modify the movement when ICSS delivery was made contingent upon holding the operandum between the bottom and entrance of the feeder for 256 or 512 msec. The efficiency of reaching (ratio of successful reaches to all reaches) decreased with increasing holding time; only a few animals were able to master a 1024 msec delay. Reaching was supported by ICSS of either lateral hypothalamus. Whereas in 8 rats the strongly expressed forepaw preference was not changed by lateralized ICSS, in 8 latently ambidextrous animals stimulation of the lateral hypothalamus ipsilateral to the preferred forepaw increased reaching with the normally non-preferred forepaw from 15% to 60%. Stimulation of the lateral hypothalamus contralateral to the preferred forepaw did not change the preference. The preference shift was equally well expressed in simple and difficult versions of the task. It is concluded that lateralization of motivational influences can be reflected in the asymmetry of the neural mechanisms processing the lateralized sensory signals and/or elaborating the lateralized motor output.     

Prenatal stimulation and postnatal testosterone affects infanticide in female rats

Prenatal handling, prenatal stress, and early postnatal exogeneous testosterone were examined in female rats for their effects on rat pup-killing and pup retrieval. During each of the last 5 days of pregnancy, Long-Evans rats received either 3 minutes of handling, 45 minutes of restraint and intense illumination or remained untouched. Half of the offspring of each group received testosterone from Day 1 after birth to Day 30. In adulthood, animals that received handling prenatally and testosterone postnatally killed pups more rapidly than any other group and a larger proportion did so than in the control groups. Animals not manipulated at any time retrieved pups more rapidly and a larger proportion did so than the combined other groups. The study suggests that prenatal handling interacts with testosterone presented immediately postnatally to increase infanticide in female rats. A variety of perinatal manipulations seem to suppress pup retrieval.     

Automatic classification of the cats vigilance state.

A special purpose hardware system has been interfaced with a minicomputer for determining the vigilance state in the cat and for quantifying delta and sigma spindle activity in the sleep EEG. The computer agreement with manual scoring is 93.8% when the state is classified as awake. non-REM, or REM sleep. The system identifies six distinct vigilance states: REM sleep, slow-wave sleep 1 or 2 (distinguished by differences in EMG level), light sleep, resting and movement. Five day averages of vigilance state and EEG activity are presented for three animals, and the effects of 5 HTP and L-dopa on delta activity and sleep spindles have been quantified for one cat in order to demonstrate the system utility.     

Auditory stimulation affects renal sympathetic nerve activity and blood pressure in rats

Here, we examined the effects of auditory stimulation at 50 dB with white noise (WN) or music (Traeumerei [TM] by Schumann or Etude by Chopin) on renal sympathetic nerve activity (RSNA) and BP in urethane-anesthetized rats. Auditory stimulation with TM, but not with WN or the Etude, significantly decreased RSNA and BP. Complete bilateral destruction of the cochleae and bilateral lesions of the auditory cortex (AuC) eliminated the effects of TM stimulation on RSNA and BP, but bilateral lesions of primary somatosensory cortex (S1C) had no effect. Bilateral lesions of the hypothalamic suprachiasmatic nucleus (SCN) or intracerebral administration of thioperamide, a histaminergic H3 receptor antagonist, also abolished TM-induced decreases in RSNA and BP. These findings suggest that exposure to music can decrease RSNA and BP through the auditory pathway, histaminergic neurons, and the SCN.     

Spinoreticular neurons in the second sacral segment of the feline spinal cord.

In continuation of previous electrophysiological studies on the location of ascending tract neurones within the second sacral segment of the feline spinal cord, the spinoreticular projections of these neurones have been investigated. Following electrical stimulation of the axonal terminals of 37 spinoreticular neurons via a tungsten electrode placed stereotactically in the contralateral nucleus reticularis gigantocellularis, antidromic potentials from their cell bodies were recorded with glass microelectrodes both extra- and intracellularly. The axons of these neurones were additionally excited from the dorsolateral funiculi of the contralateral (n = 37) and ipsilateral (n = 30) side at the lowermost thoracic spinal level. The latencies of antidromic excitation from the brainstem to the second sacral segment ranged from 3.2 to 11.8 ms (mean, 5.9 ms), whereas the corresponding axonal conduction velocities were between 27.1 and 100 m/s. The neurones examined in this study were found to be situated in the medial lamina VII of Rexed and the area adjacent to the central canal (n = 13), the medial lamina VIII (n = 12), medial laminae V and VI (n = 10) and in laminae II and III (n = 2). Three medium-sized (40-60 microm) of triangular- or oval-shaped neurones were visualized in medial laminae VII and VIII following the intracellular labelling with horseradish peroxidase.     

Mental effort affects vigilance enduringly: after-effects in EEG and behavior.

Vigilance is assumed to decline with sustained task performance. The EEG-effects during performance on mental tasks, however, cannot be ascribed indisputably to vigilance decline per se. During task performance itself, effects of information processing and vigilance decline may be confounded. In this study, effects of sustained mental effort were studied in the absence of specific information processing, after sustained information processing had taken place, namely after an effortful 70-min intelligence test. Vigilance was determined by means of EEG-measures in a rest condition. Furthermore, behavioral performance was assessed on two different tasks, the traditional Clock test and the SART. After mental effort, theta power in the EEG and errors on the SART were increased. Beta2 power, however, also appeared enhanced. We conclude that sustained mental effort produces an enduring decrease in vigilance, but that some active processing is enhanced at the same time. A second study replicated the EEG-results after mental effort.     

Olfactory stimulation with scent of lavender oil affects autonomic neurotransmission and blood pressure in rats

Previously, we observed that olfactory stimulation with scent of lavender oil (SLVO) suppressed sympathetic nerve activities and elevated gastric vagal (parasympathetic) nerve activity (GVNA), decreased plasma glycerol concentration and body temperature, and enhanced appetite in rats. Here, we further showed that olfactory stimulation with SLVO lowered renal sympathetic nerve activity (RSNA) and blood pressure (BP) and elevated GVNA in urethane-anesthetized rats. Olfactory stimulation with linalool, a component of lavender oil, also elicited decreases in RSNA and BP and an increase in GVNA in urethane-anesthetized rats. Anosmia induced by pretreatment of the nasal cavity by application of ZnSO4 eliminated the effects of both SLVO and scent of linalool on RSNA, GVNA and BP. Furthermore, intracerebroventricular administration of thioperamide, a histaminergic H3-antagonist, abolished the suppression of RSNA and BP as well as the elevation of GVNA mediated by both SLVO and scent of linalool. Finally, bilateral lesions of the hypothalamic suprachiasmatic nucleus (SCN) eliminated RSNA and BP suppression and the elevation of GVNA due to SLVO or linalool. Thus, it was concluded that scent of lavender oil and its active component, linalool, affects autonomic neurotransmission and reduces blood pressure through the central histaminergic nervous system and the SCN.     

Sleep loss affects vigilance: effects of chronic insomnia and sleep therapy

Although complaints of impaired daytime functioning are essential to the diagnosis of primary insomnia, objective evidence for cognitive dysfunction has been hard to establish. A prerequisite for understanding the neurocognitive consequences of primary insomnia is to establish task paradigms that robustly differentiate insomniacs from well-sleeping subjects. We hypothesized that the decline in performance that typically occurs with an increasing cognitive demand would provide a more sensitive measure than performance on a single task version. The hypothesis was tested, first, by assessing the performance on two vigilance tasks with different cognitive demands in 25 elderly patients with primary insomnia and 13 healthy well-sleeping age-matched subjects. Secondly, we investigated the performance response to sleep therapy using a waiting-list controlled design. Sleep therapy consisted of a multi-component intervention including sleep restriction, cognitive behavioral therapy, bright-light therapy, structured physical activity and body temperature manipulations. The results show that insomniacs differed markedly from controls in their reaction times across tasks with different cognitive demands: patients responded faster on the 'simple' vigilance task, yet slower on the 'complex' vigilance task. Sleep therapy effectively restored normal performance: patients became significantly slower on the 'simple' task and faster on the 'complex' task, returning to the performance levels of control subjects. These findings indicate that the performance decline associated with increasing cognitive demands is possibly the first sensitive and robust measure of the neurocognitive sequelae of insomnia. We suggest that future studies on cognition in primary insomnia should apply a design that varies task demands.     

Morphofunctional state of the blood microcirculatory bed in the injured gastrocnemius muscle in rats during pharmacological stimulation

The state of hemomicrocirculatory bed and of local peripheral circulation was studied after the operational injury of rat gastrochnemius muscle without pharmacologic treatment and following a combined administration of alpha-tocopherol and methyluracil. Local circulation in the regenerate of the treated animals was shown to increase not only as a result of increase of capillary density, but also due to the elevation in the number of functioning capillaries and veins.     

Olfactory stimulation with scent of grapefruit oil affects autonomic nerves, lipolysis and appetite in rats

In a previous study, we found that olfactory stimulation with scent of grapefruit oil (SGFO) excites the sympathetic nerve innervating the white adipose tissue in rats. Here we further examined the effects of SGFO in rats and observed that olfactory stimulation with SGFO excited the sympathetic nerves innervating the brown adipose tissue and adrenal gland and inhibited the parasympathetic gastric nerve. Local anesthesia of the nasal mucosa with xylocaine or anosmic treatment using ZnSO₄ eliminated the autonomic changes caused by SGFO. Moreover, stimulation with SGFO elevated the plasma glycerol level, and treatment with either ZnSO₄ or an intraperitoneal injection of diphenhydramine, a histamine H1 receptor-antagonist, abolished the glycerol elevation by SGFO. Furthermore, a 15-min exposure to SGFO three times a week reduced food intake and body weight. Finally, limonene, a component of grapefruit oil, induced reponses similar to those caused by SGFO, and diphenhydramine eliminated the glycerol response to limonene. Thus, the scent of grapefruit oil, and particularly its primary component limonene, affects autonomic nerves, enhances lipolysis through a histaminergic response, and reduces appetite and body weight.     

Exposure to PCB 77 affects the maternal behavior of rats

Polychlorinated biphenyls are environmental contaminants known to affect neurobehavioral development in many laboratory studies using different animal models. Because of their bioaccumulation and long half-life they are a serious concern for our own species. The dioxin-like PCB congener 3,4,3',4'-tetrachlorobiphenyl (PCB 77) has estrogenic and anti-estrogenic properties, and has been shown to affect brain chemistry and behavior of developing rats when administered during gestation. Since many developmental outcomes in mammals depend upon the type of maternal care provided by the dams, we investigated the effects of two doses of PCB 77 (2 and 4 mg/kg administered during gestational days 6-18) on the maternal behavior of the treated dams. Both doses of PCB 77 reduced the amount of nursing time in which the dams displayed the high-crouch posture over postnatal days 1-6. In addition, the high dose increased the amount of maternal licking and grooming of the litters and the amount of time the dams spent on the nest. The high dose also increased pup mortality, and both doses reduced the weight gain of the litters during the first 6 days of life. These results document effects of PCB 77 on maternal behavior and serve to raise questions about the importance of maternal contributions to the developmental effects of this and similar contaminants.     

Olfactory stimulation with scent of lavender oil affects autonomic nerves, lipolysis and appetite in rats

In a previous study, we presented evidence that scent of grapefruit oil excites sympathetic nerves innervating white and brown adipose tissues and the adrenal gland, inhibits the vagal nerve innervating the stomach, increases lipolysis and heat production (energy consumption), and reduces appetite and body weight. Here, we examined the effects of olfactory stimulation with scent of lavender oil (SLVO) in rats and observed that in contrast to grapefruit oil, it inhibits the sympathetic nerves innervating the white and brown adipose tissues and adrenal gland and excites the parasympathetic gastric nerve. Local anesthesia of the nasal mucosa with xylocaine or anosmic treatment using ZnSO(4) eliminated the autonomic changes caused by SLVO. Moreover, stimulation with SLVO lowered the plasma glycerol level, and treatment with either ZnSO(4) or an intracranial injection of thioperamide, a histamine H3 receptor-antagonist, abolished SLVO-mediated glycerol decline. Furthermore, a 15-min daily exposure to SLVO increased food intake and body weight. Finally, linalool, a component of lavender oil, induced responses similar to those caused by SLVO, and the glycerol response to linalool was eliminated by thioperamide. Thus, scent of lavender oil and its active component, linalool, affect autonomic nerves, suppress lipolysis through a histaminergic response, and enhance appetite and body weight.     

阳极阻滞电刺激骶神经根重构膀胱功能的作用机制

背景:课题组前期研究表明,阳极阻滞电刺激骶神经根可以改善膀胱储尿和排尿功能,但其具体分子机制未明.目的:实验采用免疫组织化学染色从蛋白功能角度对膀胱逼尿肌内神经递质受体及神经生长因子表达进行分析,探讨阳极阻滞电刺激骶神经根对膀胱功能重构的作用机制.方法:实验将新西兰兔30只随机分为对照组、脊髓损伤组和电刺激组,每组10...     

Acupuncture of the sacral vertebrae suppresses bladder activity and bladder activity-related neurons in the brainstem micturition center

Acupuncture of the sacral vertebrae has therapeutic effects in patients with overactive bladders. The mechanism of these effects, however, remains unclear. The present study, using urethane-anesthetized rats, investigated the effects of acupuncture stimulation of the sacral vertebrae on bladder activity and bladder activity-related neurons in and around Barrington's nucleus. In 95 of 147 trials (64.6%), acupuncture stimulation of the sacral vertebrae for 1 min suppressed bladder contraction for 27-2347 s. Acupuncture-induced suppression of bladder contraction was blocked by intraperitoneal injection of bicuculline (Bic). Acupuncture stimulation strongly affected bladder activity-related neurons, including those which fired only prior to the start of contraction (Type E1), those whose firing was maintained during contraction (Type E2), and those whose firing was strongly suppressed during contraction (Type I). All Type E1 neurons and most (93.8%) Type E2 neurons decreased firing when bladder activity was suppressed by acupuncture stimulation. Four of 14 (28.6%) Type I neurons exhibited an excitatory response while 3 of 14 (21.4%) exhibited an inhibitory response. These findings suggest that acupuncture stimulation of the sacral vertebrae suppresses bladder contraction and changes the firing properties of bladder activity-related neurons in and around Barrington's nucleus, and that these changes are mediated by GABAergic systems.     

Hyposensitivity to serotonergic stimulation in protein malnourished rats

Rats subjected to early protein malnutrition have higher levels of brain serotonin (5-HT) than well-nourished rats. In the present study we asked whether the elevated 5-HT levels of associated with any changes in sensitivity to serotonergic stimulation. In four different behavioral tets the effects of the 5-HT agonist N,N-dimethyltryptamine (DMT) were, with only a few exceptions, smaller in rats malnourished during both pre- and postweaning stages of development or during just one period or the other. In Experiment 1 the 5-HT syndrome induced by DMT was weaker in malnourished rats than in well-nourished ones. In Experiments 2 and 3, DMT was not a disruptive to malnourished rats in two motor tasks, rotating rod and treadmill, as it was to rats reared under high protein conditions. In Experiment 4 reductions in acoustic startle amplitudes induced by DMT were not as large in malnourished as in well-nourished rats. The hyposensitivity to DMt in protein malnourished rats may reflect a diminished sensitivity of 5-HT receptors resulting from the abnormally high levels of the neurotransmitter.     

Responses of sacral visceral afferents from the lower urinary tract,colon and anus to mechanical stimulation

The discharge characteristics of sacral visceral afferents supplying the urinary bladder, urethra, colon and anus to mechanical stimuli were analyzed in the anaesthetized cat. The stimuli used were passive distension (urinary bladder, colon), isovolumetric contraction (urinary bladder), movements of the urethral catheter and mechanical shearing stimuli (mucosal skin of the anal canal). (1) In total 245 afferent units which projected in the pelvic nerve were isolated from the sacral dorsal roots. From one of the following organs, urinary bladder, colon, urethra and anus 117 afferent units were activated. By these stimuli from the bladder, urethra and anus 122 afferent units could not be activated, and as far as tested also not from the colon; in 6 afferent units the classification was unclear. (2) Afferent units from the urinary bladder and the colon responded consistently to passive distension of the respective organ. The units from the urinary bladder showed graded responses at intraluminal pressures of about 10–70 mm Hg and responded also to isovolumetric contractions of the organ. The thresholds of the units from the bladder to passive distension and contraction varied from about 5 to 20 mm Hg intravesical pressure. (3) The afferent units from the urethra and the anus did not react or showed some weak phasic and irregular responses to distension and contraction applied to the urinary bladder or to distension of the colon. They were consistently excited by low threshold mechanical stimulation of the urethra and anus, respectively. (4) The axons from the bladder, urethra and anus were presumably myelinated (conduction velocity above 2 m/s) and conducted at 10.3±6.1 m/s (n=34, mean±SD), 26.3±9.3 m/s (n=13) and 9.5±5.1 m/s (n=37), respectively. The axons from the colon conducted at about 0.5 to 16 m/s (n=20), 13 of them conducting at less than 2 m/s. About 75% of the axons which could not be activated by mechanical stimulation of the visceral organs were presumably unmyelinated (conduction velocity below 2 m/s). (5) Some ongoing activity was found in 9 out of 26 afferent units from the anus but, with one exception, the afferent units from the bladder, urethra and colon were silent. (6) It is concluded that the pelvic afferent units from the urinary bladder, urethra, colon and anus consist of distinct populations with characteristic response patterns. There is no indication from this investigation that the urinary bladder is supplied by sacral afferents which are only recruited at high intravesical pressures during passive distension and isovolumetric contractions and which are possibly associated with pain.Supported by the Deutsche Forschungsgemeinschaft     

Cholinergic stimulation of the nucleus basalis of Meynert and reticular thalamic nucleus affects spike-and-wave discharges in WAG/Rij rats

The role of the cholinergic innervated nucleus basalis of Meynert (NB) and reticular thalamic nucleus (RT) in the generation or modulation of spontaneously occurring spike-and-wave discharges (SWDs) was investigated in the WAG/Rij rat model of absence epilepsy. The cholinergic agonist carbachol and the muscarinic antagonist scopolamine were injected in the NB and RT in the doses of 0.55 and 5.5 nmol while the EEG was recorded. Carbachol injected in the NB decreased the number and the mean duration of SWDs. Scopolamine alone had no influence on SWDs, but could antagonize the effects of carbachol if administered simultaneously in NB. Injections of carbachol in the RT inhibited the occurrence of SWDs, but did not affect the mean duration. Scopolamine administered in the RT had no influence on seizure activity. It is concluded that cholinergic stimulation of the NB or the RT inhibits the cortical synchronous activity characterizing SWDs.     

Vasomotor response to thermal stimulation of the scrotal skin in rats

Summary In 27 anesthetized rats arterial blood pressure and electrical activity of dorsal horn neurones were recorded during thermal stimulation of the scrotal skin. In 19 of these animals blood pressure increased during scrotal skin warming, showing a distinct threshold at about 37.5°C in 16 rats. This effect was reproducible during the whole experiment although quantitative changes of the response occurred. In most experiments a transient response was seen at the beginning of the vasomotor reaction. The mean increase of blood pressure to a superthreshold warming step, derived from 11 experiments in which more than 3 temperatures were tested and in which the blood pressure was above 100 mm Hg, was 25±14 mm Hg. The observed threshold of the vasomotor response corresponds well with the threshold of activity increase in warm sensitive dorsal horn neurones to scrotal skin warming. It is suggested that the blood pressure reaction is mediated by scrotal skin warm receptors, which supports the notion that some organ specificity exists in thermoreceptors of the scrotal skin.     

Responses to taste stimulation in the ventroposteromedial nucleus of the thalamus in rats

Extracellular action potentials were recorded from 73 neurons in the parvicellular division of the ventroposteromedial (VPMpc) nucleus of the thalamus of anesthetized Wistar rats during gustatory, thermal, and tactile stimulation of the whole oral cavity. The stimulus array consisted of 16 room-temperature (23 degrees C) sapid stimuli, distilled water at three temperatures (0, 23, and 37 degrees C), and 0.1 M NaCl at three temperatures (0, 23, and 37 degrees C). Among all 151 neurons isolated in VPMpc, 9% responded exclusively to taste, 33% to taste and temperature, none to taste and touch, but 6% to all three modalities. Discharge rates evoked by the basic tastants were 13.8 +/- 1.6 (SD) spikes/s for 0.1 M NaCl, 9.3 +/- 1.4 spikes/s for 0.01 M HCl, 5.1 +/- 0.9 spikes/s for 0.5 M sucrose, and 4.3 +/- 0.6 spikes/s for 0.01 M quinine HCl. Water evoked mean responses at 0, 23, and 37 degrees C of 9.9 +/- 1.5, 0.6 +/- 0.4, and 1.3 +/- 0.9 spikes/s, respectively. The mean firing rate evoked by 37 and 0 degrees C NaCl was 15.0 +/- 2.4 and 17.0 +/- 2.8 spikes/s, respectively. The exponent of the NaCl concentration-response power function was 0.39. Thalamic taste cells were broadly tuned. The mean breadth-of-tuning coefficient for these 73 gustatory cells was 0.79 +/- 0.02. Two cells responded predominantly with inhibition, which accounted for the majority of inhibitory responses. The taste neurons were statistically divisible into three groups: sodium-oriented (n = 40), acid-oriented (n = 12), and sugar-oriented (n = 17). Four additional bitter-oriented neurons were not closely enough related to be defined as a group and were considered outliers. The sodium-oriented group could be divided into three statistically distinct subgroups, differing in the specificity of their responses to NaCl. With respect to polymodal sensitivity, spontaneous rate, evoked response rates, signal-to-noise ratio, proportions of cells responding best to basic tastants, taste neuron groups, taste spaces, and temporal responses, VPMpc neurons have characteristics that are intermediate between those of parabrachial and cortical gustatory neurons.     

Cortical temperature and EEG slow-wave activity in the rat: analysis of vigilance state related changes

Vigilance states, cortical temperature (T _CRT), and electroencephalograph (EEG) slow-wave-activity (SWA, mean power density in the 0.75–4.0 Hz range) of ten rats were recorded continuously during a baseline day, and two recovery days (Recovery 1 and 2) after 24 h of sleep deprivation (SD). The short term changes of T _CRT were analysed within episodes of nonrapid eye movement sleep (NREMS), REM sleep (REMS) and waking (W), and at transitions between vigilance states. SWA was analysed within NREMS episodes and at W to NREMS (WN) transitions. T _CRT increased during episodes of W and REMS, and decreased during NREMS episodes. These changes were a function of episode duration, and, for W and NREMS, of T _CRT at episode onset. In Recovery 1 the increase in T _CRT at NREMS to REMS (NR) and NREMS to W (NW) transitions tended to be attenuated. SWA within NREMS episodes was enhanced after SD. Over all experimental days, the increase of SWA and the decrease of T _CRT in NREMS episodes were not correlated.It is concluded that during recovery from SD the changes in T _CRT at state transitions were little affected. The lack of a relationship between changes in T _CRT and SWA indicates that separate mechanisms underlie the regulation of brain temperature and sleep intensity.