Botulinus toxin: effect on the central nervous system of man

Electrical stimulation of multiple peripheral nerves, elicited "H" reflexes in a patient, 61 years old, with botulism. These reflexes are extremely suggestive of some central release or failure of inhibitory control of a monosynaptic or polysynaptic spinal reflex arc. This "central" action of botulinus toxin is similar to that suggested for tetanus toxin.     

Sexual differentiation of the central nervous system

Sexual differentiation of reproductive and behavior patterns is largely effected by hormones produced by the gonads. In many higher vertebrates, an integral part of this process is the induction of permanent and essentially irreversible sex differences in central nervous function, in response to gonadal hormones secreted early in development.     

Retrograde axonal transport in the central nervous system

When horseradish peroxidase is injected into the optic tectum of a chick, axons of ganglion cells transport it centripetally to their cell bodies in the retina at a rate of about 72 millimeters per day. After intraocular injections in the young chick, the peroxidase is transported centripetally along efferent axons, and is concentrated in cell bodies within the isthmo-optic nucleus. This retrograde movement of protein from axon terminal to cell body suggests a possible mechanism by which neurons respond to their target areas.     

广西兔业产业化的构成体系及发展模式的选择

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Transneuronal transfer of radioactivity in the central nervous system

After injection of tritiated amino acid into the mouse eye, radioactivity appeared in the contralateral visual cortex, indicating that some material had been transferred from optic axons to lateral geniculate neurons. The radioactivity in the cortex was about 2 percent of that arriving in the geniculate, and most of it was contained in material that appeared to be protein.     

Habituation and dishabituation in the absence of a central nervous system

Habituation and dishabituation have been observed in a semi-intact Aplysia preparation in which the central nervous system is removed. The amplitude of withdrawal responses in the gill decreases in proportion to the rate of water drops applied (one drop per 0.5 minute to one drop per 2.5 minutes at 15 degrees C). The effects of habituation last for at least 2 hours. A dishabituated response is elicited by stopping the water drops or electrically stimulating the preparation. Furthermore, the gill contains nerve cell bodies, and habituation and dishabituation appear to be properties of these peripheral neurons.     

Excitatory and inhibitory motoneurons in the central nervous system of the leech

The locomotion and reflex responses of the leech are brought about by inmuscles that are arranged in a regular, simple pattern in the body wall and that flatten, shorten, lengthen, or bend the animal. In the segmental ganglia, it is possible to recognize by morphological and physiological criteria the individual motoneurons that cause contractions and relaxations of these muscles.     

Immunocytochemical detection of acetylcholine in the rat central nervous system

A specific antibody to acetylcholine was raised and used as a marker for cholinergic neurons in the rat central nervous system. The acetylcholine conjugate was obtained by a two-step immunogen synthesis procedure. An enzyme-linked immunosorbent assay was used to test the specificity and affinity of the antibody in vitro; the results indicated high affinity. A chemical perfusion mixture of allyl alcohol and glutaraldehyde was used to fix the acetylcholine in the nervous tissue. Peroxidase-antiperoxidase immunocytochemistry showed many acetylcholine-immunoreactive cells and fibers in sections from the medial septum region.     

Neuroscience. Stout guards of the central nervous system

Endocannabinoids have paradoxical effects on the mammalian nervous system: Sometimes they block neuronal excitability and other times they augment it. In their Perspective, Mechoulam and Lichtman discuss new work (Marsicano et al.) showing that activation of the cannabinoid receptor CB1 by the endocannabinoid anandamide protects against excitotoxic damage in a mouse model of kainic acid-induced epilepsy.     

Thyrotropin-releasing hormone effects in the central nervous system: dependence on arousal state

Thyrotropin-releasing hormone was microinjected into the dorsal hippocampus of ground squirrels (Citellus lateralis) when they were at different levels of arousal, as assessed by electrophysiological and behavioral criteria. When administered to the awake animal, thyrotropin-releasing hormone produced dose-dependent decreases in body temperature accompanied by behavioral quieting and reductions in metabolic rate and electromyographic activity. The magnitude of these effects was greater when the peptide was microinjected during a period of behavioral activation. In contrast, administration of the peptide during slow wave sleep produced increased thermogenesis, an increase in electromyographic activity, and an increase in the amount of electroencephalographic desynchronization.     

Poliovirus inhibitor from the central nervous system of the Rhesus monkey

The production of riboflavin by Eremothecium ashbyii is appreciably reduced by 3-amino-1,2,4-triazole at concentrations of inhibitor which do not inhibit growth. Corn and pea leaf tissues which are albinistic as a consequence of treatment with this compound have a greatly lowered riboflavin content.     

beta-Adrenergic regulation of alpha 2-adrenergic receptors in the central nervous system

Incubation of rat cerebral cortical slices with the beta-adrenergic agonist isoproterenol causes an increase in alpha 2-adrenergic receptor binding in addition to a decrease in beta-adrenergic receptor binding. The effects are rapid and reversible, show a parallel time course, and are blocked by sotalol, a beta-adrenergic receptor antagonist. The beta-mediated regulation of alpha 2-receptor sensitivity at brain norepinephrine synapses may be a mechanism for the homeostatic control of central noradrenergic activity.