Under the influence of the nerve growth factor (NGF) a general stimulation of the synthetic processes, especially protein synthesis, occurs in the neuroblasts. The morphological counterpart is an hypertrophy of the nucleoli and spiralization of nucleolonema, an increase of the number of ribosomes with the persistence of a specific organization for each stage of development, then the proliferation of the granular endoplasmic reticulum and the modification of the predominant shape of mitochondria, which becomes annular, their outer surface being largely increased. The nutrient stores are quickly exhausted, with an accelerated disintegration of yolk droplets. There is an obvious increase in the number of non-synaptic contacts (puncta adherentia) between processes of neuroblasts and neighbouring nervous structures, and also an acceleration of formation of typical synaptic zones, indicating that NGF stimulates the functional maturation of the nervous system.

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PubMedDate not supplied

Subarachnoid midazolam: histologic study in rats and report of its effect on chronic pain in humans.

Subarachnoid administration via a catheter of a water-soluble benzodiazepine, midazolam, was tested in the control of cancer pain. First, the lack of its toxicity during constant subarachnoid administration (50 micrograms per day) was assessed in the rat. After 15 days of treatment, a histologic examination of the spinal cord revealed the same amount of fibrosis, infiltration, and deformation in the control group (n = 14), which had received only saline, as in the test group (n = 18), treated with subarachnoid midazolam. Therefore, the histologic changes observed in the spinal cord probably are related to the presence of the catheter. After these results, a mixture of 2 mg midazolam and a variable dose of subarachnoid morphine was injected in two patients presenting chronic neoplastic pain resistant to high doses of morphine. In these two cases, the addition of midazolam appeared to be effective in controlling intractable neoplastic pain.

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PubMedDate not supplied

[Morphofunctional characteristics of serotonin-like neurons in the hypothalamus of rats in ontogeny].

An attempt has been made to reveal 5-HT immunopositive (IP) neurones in the hypothalamus of intact foetuses (18th day of gestation) and neonatal (9-day) rats under normal conditions and after their treatment with drugs involved into 5-HT metabolism or into regulation of its uptake by serotoninergic neurones. 5-HTIP cells were not observed in intact animals as well as after L-tryptophan treatment, whereas two large colonies of these neurones were found in the anterio-lateral hypothalamus and dorsomedial nucleus after subsequent injections of monoamine oxidase inhibitor, pargyline, and amino acid precursor of 5-HT synthesis, L-tryptophan. Significantly less intensive reaction was observed after injections of another precursor of 5-HT synthesis, 5-hydroxytryptophan, or pargyline only. Immunostaining evoked by pargyline or L-tryptophan can be prevented by preliminary injections of fluoxetine, a specific inhibitor of 5-HT uptake by serotoninergic neurones. These data suggest that the immunostaining of hypothalamic neurones is due to their capacity to take up specifically 5-HT from the environment rather than to its intraneuronal synthesis from L-tryptophan. However, 5-HT synthesis from 5-hydroxytryptophan in the same cells may also take place. The uptake of extracellular 5-HT by catecholaminergic neurones is absent, since nomifensine, a specific inhibitor of this uptake, does not affect immunostaining.

5-Hydroxytryptophan↗

PubMedDate not supplied

[Radioautographic study of the hypothalamic serotoninergic structures in the perinatal period of the rat].

The distribution of 3H-serotonin-binding structures in hypothalamus of 16 and 18 day old fetuses and of 9 day old rats was studied after intraventricular injection of 3H-serotonin. Rare 3H-serotonin-binding little differentiated cells were found predominantly in the intermediate zone of the 3rd ventricle in the retrochiasmatic area wall on the 16th and 18th days of prenatal development. In addition, an aggregate of heavily labeled neurones was observed in the suprachiasmatic area. At the same time 3H-serotonin-binding fibers first appeared, predominantly in the optic chiasma and perichiasmatic area. Radioactively labelled cells, which can be characterized by their morphology as differentiated neurones, were located in the dorsomedial nucleus on the 9th day of postnatal development. The number of serotonin-binding fibers markedly increased but the pattern of their distribution was, on the whole, similar to that in fetuses. The data obtained suggest that the main stages of structural organization of serotoninergic system of hypothalamus in rats are realized during perinatal period.

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