Transplantation into the mammalian adult spinal cord

Summary Embryonic cerebral cortical tissue obtained from rat embryos of 15-day gestation was transplanted into the cervical spinal cord of adult rats. The cortical transplants survived, grew, and established connections with the host animal's spinal cord. In other animals, knife lesions were first made in the host's spinal cord, and then embryonic cortical tissue was transplanted into the site of the lesion. The cortical transplants in these animals were observed to become an integral part of the host animal's spinal cord.     

Mechanism of age-dependent involution in embryonic chick notochords

To study the possible mechanism of the age-dependent involution of the notochord, isolated mesenchymefree notochords of chick embryos were cultured in vitro and compared with their counterparts in vivo. Two different aspects were evaluated: (1) DNA synthesis measured by [³H]thymidine incorporation and visualized by autoradiography and (2) cell death quantified by counting the number of pyknotic nuclei. The results demonstrate that [³H]thymidine uptake by notochords shows an age-dependent decrease in vitro as well as in vivo. The number of [³H]thymidine-labelled notochord cells, however, is higher in vitro than in vivo. At the same time, there is an age-dependent increase in pyknosis in the notochord in vivo and in vitro. So, during the aging process, the number of both pyknotic nuclei and of [³H]thymidine-labelled nuclei suggest a high turnover of notochord cells in vitro. From these results, we can conclude that the process of involution in aging notochord seems to be controlled by a programmed intrinsic process, which might be influenced partially by the microenvironment in vivo.     

Serotonergic and cholinergic interaction in the regulation of pituitary-adrenal function in rats

It has been proposed that the central serotonergic inputs which modulate pituitary-adrenal secretion are mediated by cholinergic neurons. We have tested this hypothesis in intact rats. Male Sprague-Dawley rats were injected with cholinergic and serotonergic agents which enhanced transmitter function and with receptor blocking agents. Agents were injected, singly and in combination, into both unstressed and stressed animals. Since the response to cholinergic agents might be due to changes to vasopressin release, Brattleboro (vasopressin deficient) rats were also injected with cholinergic agents. The level of plasma corticosterone at 1-h post-injection was determined. Results indicate that the serotonin receptor blockade decreased the stimulatory, cholinergic effect of physostigmine. Cholinergic receptor blockers did not significantly reduce the corticosterone rise induced by 5-hydroxytryptophan. These results do not support the hypothesis of cholinergic mediation of serotonergic input. Nicotinic and muscarinic receptors appeared to exert opposing influences on the system. The nicotinic receptor antagonist was able to block the stimulatory effect of physostigmine. The muscarinic receptor antagonist significantly elevated plasma corticosterone levels. No differences were found in the effect of physostigmine on Brattleboro rats as compared to controls. These data are interpreted as suggesting that 1) the acetylcholine-induced stimulation of pituitary-adrenal function is mediated, in part, by serotonergic neurons; and 2) stimulation of nicotinic receptors is facilitatory whereas stimulation of muscarinic receptors is inhibitory to pituitary-adrenal function.     

Fluorogenic amines in the notochords of chick embryos treated by cholinergics]

The investigation of 3 day old notochords by the fluorescence method of Falck and Owman showed an increase of the fluorescence after treatment of the chick embryos at 48 hrs of incubation, with nicotine sulfate or carbachol. The addition of norepinephrine or L-Dopa emphasized the formaldehyde induced fluorescence. The simultaneous treatment with a cholinergic agent and atropine, propranolol or reserpine decreased or suppressed the fluorescence. These results demonstrate the existence of a relationship between the treatment with a cholinergic agent and the amount of chordal biogenic amines.     

The chordate amphioxus: an emerging model organism for developmental biology

The cephalochordate amphioxus is the closest living invertebrate relative of the vertebrates. It is vertebrate-like in having a dorsal, hollow nerve cord, notochord, segmental muscles, pharyngeal gill slits and a post-anal tail that develops from a tail bud. However, amphioxus is less complex than vertebrates, lacking neural crest and having little or no mesenchyme. The genetic programs patterning the amphioxus embryo are also similar to those patterning vertebrate embryos, although the amphioxus genome lacks the extensive gene duplications characteristic of vertebrates. This relative structural and genomic simplicity in a vertebrate-like organism makes amphioxus ideal as a model organism for understanding mechanisms of vertebrate development.Received 18 February 2004; received after revision 9 April 2004; accepted 19 April 2004     

Effect of piperazine on central and peripheral cholinergic synapses of the frog.

The anthelmintic agent piperazine did not antagonize carbachol-induced depolarizations of the frog sartorius muscle but depressed root potentials and acetylcholine release from the frog spinal cord. We suggest that piperazine has a presynaptic site of action at central cholinergic nerve-terminals.     

Effect of piperazine on central and peripheral cholinergic synapses of the frog

Summary The anthelmintic agent piperazine did not antagonize carbachol-induced depolarizations of the frog sartorius muscle but depressed root potentials and acetylcholine release from the frog spinal cord. We suggest that piperazine has a presynaptic site of action at central cholinergic nerve-terminals.     

Effects of ablation of the hindlimb on the organization of the ventral horn of the spinal cord in the lumbar region of green lizard embryos (Lacerta viridis Laur.)]

After extirpation of an hind limb in embryos of Lacerta viridis, numerous motor neuroblasts degenerate on the operated side, in the ventral horn of the lumbar spinal cord and the corresponding motor column is reduced or disappears. The lumbar spinal ganglia are affected and reduced on the operated side.     

Capture and fixation of tritiated serotonin by chick embryo notochord]

The 3 day old Chick notochord capacity to fix tritiated serotonin is maximal in its axis and in cephalic region. Our observations permitting us to find, the intracellular serotonin binding sites, contribute to an explanation of the capture mechanism and suggest a special direct role of the notochord on the monoaminergic neuron cytodifferentiation.     

New observations on the representation of the eye muscle proprioception within the descending trigeminal nucleus.

Units responding to stretch of single extraocular muscles were found in the bulbar and cervical portion of the descending trigeminal nucleus of the lamb. The electrolysis of these bulbar sites provoked degeneration of nervous fibres which could be followed till the first cervical segment of the spinal cord.     

Effects of chronic paralysis of chick embryo by flaxedil on the development of the neuromuscular junction]

Chronic paralysis of Chick embryos by the cholinergic antagonist flaxedil blocks the subsynaptic accumulation of acetylcholinesterase but not the formation of acetylcholine receptor cluster. Flaxedil paralysis also causes an increase of the total muscle content of acetylcholine receptor without altering the half-life of the receptor protein. The spontaneous activity of the embryon therefore "shuts off" the synthesis of extrasynpatic acetylcholine receptor.     

Organization of the ventral branchial and lumbar horns of the spinal cord in embryos of snake-like and tetrapod reptiles]

In embryos of Snake-like Reptiles (Anguis fragilis) and of Ophidians (Tropidonotus, Python), the lay-out of motor neuroblast in the ventral horns of the spinal cord, in the brachial and the lumbar regions differs from the one observed in the same regions of embryos of tetrapod Reptiles (Lacerta viridis).     

Nonsympathetic dilator innervation of cat cerebral arteries.

The results presented provide strong support for the presence of vasodilator innervation in the cat cerebral arteries. The dilator innervation is neither adrenergic nor cholinergic and does not originate in the superior cervical ganglia. The nature of the vasodilator transmitter is unidentified. Such innervation, however, may be involved in the regulation of cerebral blood flow, especially in view of the capability of some cat cerebral vessels to develop intrinsic muscle tone.     

Elektronenmikroskopischer Nachweis spezifischer Grana in den Sympathicoblasten der Grenzstrangganglien von Hühnerembryonen

Summary With regard to the cytodifferentiation of neurones in the developing CNS and the spinal ganglia, only the sympathoblasts of the primary and secondary sympathic trunk of chick embryos contain a varying amount of catechol amine-containing granules. The formation of these granules takes place in rather early stages of development.     

Plasma cyclic 3',5'-guanosine monophosphate and cyclic 3',5'-adenosine monophosphate response to methacholine in man

Cholinergic agents are known to induce increases in tissue and plasma levels of cyclic GMP in experimental animals. We observed that i.m. injection of methacholine, a cholinergic agent, caused significant increases in plasma cyclic GMP and cyclic AMP in man.     

Attraction of primordial germ cells by notochord in seven somites chick embryo

Summary Chemical studies in chick embryo have indicated the existence of proteoglycan in notochordal sheath. Primordial germ cells were observed with scanning electron microscope on the notochord dorsal face, surrounded with perichordal material. We postulate the identification of such a material with proteoglycan which could attract primordial germ cells to the notochord.     

Plasma cyclic 3′,5′-guanosine monophosphate and cyclic 3′,5′-adenosine monophosphate response to methacholine in man

Summary Cholinergic agents are known to induce increases in tissue and plasma levels of cyclic GMP in experimental animals. We observed that i.m. injection of methacholine, a cholinergic agent, caused significant increases in plasma cyclic GMP and cyclic AMP in man.     

Response of respiration to selective heating of the spinal cord below partial transection

Conclusions The experiments indicate that the signals arising from thermal stimulation of the spinal cord are conducted to higher spinal and to supraspinal thermoregulatory effector systems by afferent fibers which run in the ventrolateral, but not in the dorsal portions of the spinal ascending tracts. This corresponds to the observation ofWünnenberg andBrück that shivering induced by external cooling is not inhibited by heating the lower cervical and upper thoracic spinal cord, if the ventral funiculi are transected at a higher cervical level. -These findings are parallel to the observation that the inhibitory effect on shivering of skin pressure is no longer present after contralateral transection of the ventrolateral funiculus at a higher level, i. e. after transection of the so-called ventral spinothalamic tract. Likewise, it has been observed that modifications of electrocortical activity following thermal stimulation of the skin or following changes of environmental temperature are abolished, if the ventrolateral funiculi are transected at the cervical level. -It may be suggested, therefore, that the afferent signals arising from spinal thermosensitive structures might follow the same ascending pathway as do the discharges of peripheral thermodetectors.

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Zusammenfassung Der Einfluss thermischer Reizung des Rückenmarks unterhalb einer Teildurchschneidung in Höhe von Th 4–Th 11 auf Atmung, Hautdurchblutung und motorische Aktivität wurde an leicht narkotisierten Kaninchen untersucht. Mittels Marchi-Färbung einige Tage nach Durchschneidung wurden die ausgeschalteten afferenten Bahnen ermittelt. Nach Durchschneidung der Hinterstränge und anschliessender Abschnitte der Seitenstränge konnte durch Rückenmarkwärmung unterhalb der Durchschneidung eine thermische Tachypnoe und eine Hautvasodilatation oberhalb der Durchschneidung ausgelöst werden. Diese Reaktion war nach Durchschneidung der Vorderseitenstränge erloschen.

     

Influence of metiamide and atropine on pepsinogen secretion in the conscious rat

Activity of peptic cells is influenced directly by cholinolytic or cholinergic agents. Histamine H2-antagonists influence the activity of the chief cells through changes of acidity of gastric juice.     

Lipofuscin accumulation in squirrel monkey spinal cord consequent to protein malnutrition during gestation.

The formation of lipofuscin pigment in the anterior horn cells of the cervical spinal cord has shown in the fetuses and neonates under the extrinsic influence of maternal protein deprivation during the gestation period in the squirrel monkeys.