ISSN:0006-8977    

DOI:10.1159/000121480

出版商:S. Karger AG    

年代:1983

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000121481

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Space sickness is generally considered a variant of motion sickness although not fully proved as such. Understanding space sickness requires objective and quantitative characterization of the disorder. Vomiting is a quantifiable physiological event performed by the respiratory muscles which generate the pressures that evacuate the gut. Vomiting from all causes is coordinated by the vomiting center in the medulla oblongata. The emetic chemoreceptor trigger zone (CTZ) in the area postrema is thought to be an indispensable element in the afferent pathway of motion sickness. About 30 potential neurotransmitters exist in the vomiting control mechanism which includes at least eight chemical transmission steps through the reflex pathway of motion sickness. Individual synaptic transmitters do not likely mediate specific functions, but particular combinations of those transmitters might well serve distinct functions. Adaptation to the cause of space sickness probably results from readjustment of a cerebellar circuit or of a humoral factor acting on the CTZ, rather than from stimulus-receptor desensitization. Space sickness must, for purposes of investigation, be treated as a unique disorder engendered by weightlessness until proved equivalent to any emetic syndrome that occurs on earth.

ISSN:0006-8977    

DOI:10.1159/000121482

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Each of 8 young adult female squirrel monkeys were injected via a femoral vein cannula with 167 µCi/100 g body weight of 2-(1,2–3H)-deoxy-D-glucose (2-DG) (New England Nuclear, 37,3 Ci/mmol) in 0.5 ml sterile saline. 4 additional female squirrel monkeys were injected in the same manner with 100 µCi/100 g body weight of the (3H)-2-DG. 2 h after this initial injection the original 8 animals were injected with 16.7 µCi/100 g body weight of 2-(1-14C)-deoxy-D-glucose (51.3 mCi/mmol) in 0.5 ml sterile saline. The 4 additional animals were injected with 25 µCi/100 g body weight of the (14C)-2-DG. Half of the animals at each dose level were restrained in the upright position with Velcro straps and a nontraumatic moulded plastic head holder on a modified animal restraint board [Withrow and Devine, 1972] with the head in the sagittal plane but tilted forward about 20°. They were then subjected to horizontal rotary motion at 25 rpm together with a vertical movement of 6 inches at 0.5 Hz for 1 h in a lighted room. The other half of the animals at each dose were restrained in the same manner and maintained in a quiescent state. At the end of this period each animal was anesthetized with ketamine, and the brain was quickly dissected out and frozen in isopentane cooled to –60°C with dry ice. Transverse cryostat sections (–15°C) of the brainstem were cut alternately at 200 and 20 µm from the nucleus gracilis caudally through the superior vestibular nucleus rostrally. Micropunch samples of the individual vestibular nuclei, and other brainstem nuclei and areas were obtained from the 200-µm sections with a modification of the method of Eik-Nes and Brizzee with a small stainless steel punch measuring 850 µm in diameter. The frozen punch samples were prepared for liquid scintillation counting (Beckman LS7500 system). Differential (3H) and (14C) counts (cpm) were made employing external standards. The 20-µm sections were prepared for 14C autoradiography by standard methods employing Kodak SB-5 X-ray film. The (14C) autoradiography from the motion-stimulated animals revealed a selectively high uptake of 2-DG in all of the vestibular nuclei, the lateral cuneate nucleus and the lateral reticular nucleus as compared with the corresponding structures in the control animals. The area postrema and nucleus of the solitary tract also exhibited somewhat higher grain density in motion-stimulated as compared with control subjects. The inferior olive showed a heavy 2-DG uptake in nearly all subjects but the brain density appeared somewhat higher in motion-stimulated animals. Data from the liquid scintillation counts revealed that the 14C/3H ratio (cpm) was significantly higher (p < 0.05) in the medial and inferior vestibular nuclei and nucleus cuneatus in motion-stimulated than in control animals. Values for the other vestibular nuclei and dorsal reticular formation (region of the vomiting center), and nucleus of the solitary tract were high but did not attain the level of statisti

ISSN:0006-8977    

DOI:10.1159/000121483

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Vestibular stimulation, by means of sinusoidal electrical polarization of the labyrinths of decerebrate cats, can produce vomiting and related activity resembling that seen in motion sickness. The symptoms include panting, salivation, swallowing, and retching as well as vomiting. These symptoms can be produced in cats with lesions of the posterior cerebellar vermis. In contrast to a previous proposal by Wang and Chinn in 1956, we suggest that a transcerebellar pathway from the vestibular apparatus through the nodulus and uvula to the ''vomiting center'' is not essential for vestibular-induced vomiting and, by analogy, for the occurrence of many symptoms of motion sickness.

ISSN:0006-8977    

DOI:10.1159/000121484

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Motion sickness occurs in a wide variety of circumstances involving real or apparent motion, many of them novel and man-made. Significantly, voluntary body movements rarely result in symptoms, and the likelihood of motion sickness is greatly reduced by having control of the vehicle in which one is riding. The unifying theory of Reason [1978] proposes that motion sickness results when there is a mismatch between predicted and actual sensory inputs. Hence, the less predictable the sensory input (because it results from an externally imposed motion, or from motion which results in errors of neural transduction), the more likely that motion sickness will develop. With continuing exposure, predictability increases and adaptation to motion sickness occurs.

ISSN:0006-8977    

DOI:10.1159/000121485

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The possibility that there might be a neurohumoral cerebrospinal fluid (CSF) link in motion sickness was directly tested in cats by blocking the flow of CSF from the third into the fourth ventricle. Evidence obtained thus far is consistent with the hypothesis. Cats with demonstrably sound blocks did not vomit in response to an accelerative motion sickness stimulus, whereas cats with imperfect ''leaky'' blocks vomited with little or no increase in latency. Although there are several putative candidates, the identification of a humoral motion sickness substance is a matter of conjecture.

ISSN:0006-8977    

DOI:10.1159/000121486

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The evidence for possible roles of catecholamines in motion sickness is reviewed. l-Dopa is implicated in that it is the precursor to catecholaminergic neurotransmitters. Dopamine may have a role in stimulating motion sickness, though much basic information is lacking. Epinephrine may have a stimulatory role, since anatomical, pharmacological and physiological evidence is consistent with such a role. Norepinephrine probably inhibits motion sickness, as indicated by anatomical, physiological and pharmacological evidence. Information is missing that is critical to the understanding of the roles of each neurotransmitter in motion sickness.

ISSN:0006-8977    

DOI:10.1159/000121487

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Retrograde HRP studies indicated that motoneurons innervating soft palate and pharynx are located in especially the dorsal group of the nucleus ambiguus, while motoneurons innervating upper esophagus and cricothyroid muscles are located in the retrofacial nucleus, the most rostral part of the nucleus ambiguus. Autoradiographic tracing techniques revealed that in the caudal pontine tegmentum an area is located just dorsal to the superior olivary complex, that projects contralaterally to the ventral part of the trigeminal motor nucleus, the dorsal group of the nucleus ambiguus and the ventral part of the hypoglossal nucleus. In these areas motoneurons are located innervating the mylohyoid, soft palate, pharynx and geniohyoid muscles respectively. Since these muscles are all involved in swallowing, a possible involvement of this pontine tegmental area in swallowing is discussed.

ISSN:0006-8977    

DOI:10.1159/000121488

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The intrinsic and extrinsic connections of the parvicellular reticular formation (PCRF) that have been demonstrated by fiber degeneration studies and studied by more recently introduced horseradish peroxidase retrograde cell labeling are reviewed in an attempt to delgit the connectivity of the region in the PCRF where electrical stimulation produced emesis. Evidence is presented that certain specific functional subdivisions in PCRF such as the salivatory nuclei and the cells which give rise to the vestibular efferent projections can be delimited.An attempt is made to differentiate the sources of brain stem afferent connections with the nucleus of the tractus solitarius, the vagal nucleus and the nucleus ambiguus complex. The literature bearing on the histochemistry of the brain stem is reviewed in a search for clues to possible unique histo- or immunochemical cytological subdivisions in the parvicellular reticular formation.

ISSN:0006-8977    

DOI:10.1159/000121489

出版商:S. Karger AG    

年代:1983

数据来源: Karger