Acta biologica Academiae Scientiarum Hungaricae最新文献

Studies on fluorescent histochemical localization of monoamines in strips of connective tissue teared off the electric organ of Torpedo marmorata revealed an extensive system of yellow fluorescent nerve fibres. No green fluorescent (catecholamine-containing) axons were found in this region. The significance of the presence of indole-containing axons in the connective tissue of the electric organ is in accordance with previous findings on a high level of serotonin in the Torpedo electric organ and contradicts the general assumption that the electric tissue is a source of purely cholinergic nerve endings.

An account of the origin of the term liaison brain leads on to an historical account of its usage, particularly in voluntary movement. Empirical evidence was provided by the readiness potential of Kornhuber and associates, which even indicated a key role for the supplementary motor area, SMA. It was found by Brinkman and Porter that in voluntary movement many neurones of the SMA were activated probably up to 200 msec before the pyramidal tract discharge. Then came the (133)Xe investigations of regional cerebral blood flow by Roland and associates to reveal that there was neuronal activity in the SMA of both sides during a continued series of voluntary movements, and that his even occurred when the movement was being thought of but not executed. The microstructure and connectivities of the SMAS are considered in relationship to its proposed key role in being excited by the mental act of intention and then calling up the appropriate motor programs to give the desired movement: each mental intention would act on the SMA in a specific manner; the SMA has an 'inventory' and the 'addresses' of stored subroutines of all learnt motor programs and so is able to institute the desired movement by its neuronal connectivites. In conclusion there is a general account of the concept of the liaison brain both for intention and perception.

Synapse is the most common and generally accepted structural basis for the interaction between neurons. It provides a "one-to-one" communication system between neurons. However, there is another possibility for interneuronal communication: when one neuron communicates with many others without making synaptic contact. In the past few years neurochemical, morphological and pharmacological evidence has been obtained that some neurotransmitters may be released from non-synaptic sites, for diffusion to target cells more distant than those seen in conventional synaptic transmission. The non-synaptic interneuronal communication between neurons plays a physiological role in the presynaptic modulation of chemical neurotransmission. This would be a transitional form between the classical neurotransmission and the broadcasting of neuroendocrine secretion.

Dorsal root fibers were labelled with cobalt and their terminals were identified in an oval-shaped area and in its lateral extension of the dorsal horn. These areas receive mainly cutaneous afferents. A number of labelled terminals exhibited either an electron lucent and swollen, or an electron dense and shrunken form of degeneration. The majority of the labelled terminals could be classified into three groups. Type A terminals were small, less than 2 microns in diameter, and lightly stained. Type B terminals were larger and neurofilaments and an electron dense material resulted in a dark staining of the bouton. Type C terminals contained medium size granulated vesicles. The type A and type B terminals were frequently found in postsynaptic positions. The presynaptic profiles contained spheric or elliptic vesicles, or they exhibited the structural characters of presynaptic dendrites. Preterminal dorsal root fibers, identified on account of their cobalt label, were also found in postsynaptic positions to the same kinds of presynaptic profiles. It is concluded that cobalt labelling is sufficiently selective for a reliable identification of dorsal root terminals. No correlation was found between the different forms of degeneration and the different types of terminal boutons. The possible functional significance of the postsynaptic relation of dorsal root fibers and terminals to a variety of presynaptic profiles is discussed.

If applied locally around a peripheral sensory nerve, Formyl-Leurosin, a semi-synthetic diindol alkaloid of Vinca rosea--that, just like other mitotic spindle inhibitors, induces blockade of axoplasmic transport via inhibiting microtubular function--causes transganglionic degenerative atrophy of central terminals of primary nociceptive neurons in the substantia gelatinosa Rolandi of the spinal cord. In contrast, if applied to dorsal roots, Formyl-Leurosin fails to induce such alterations. Based upon these observations it is postulated that blockade of retrograde axoplasmic transport, rather than that of the orthograde one, is the decisive factor in the pathomechanism of transganglionic degenerative atrophy.

Incorporation of 3H-uridine by RNA in Tetrahymena was differently influenced by insulin, glucagon, follicle-stimulating hormone (FSH), thyrotropic hormone (TSH), adrenocorticotropic hormone (ACTH) and chorion-gonadotropic hormone (PMSG). TSH caused it to increase considerably and durably after an initial depression, while glucagon caused it to rise over the control throughout. Insulin, and especially PMSG, depressed the incorporation of label considerably, the latter to 3-6% of the control value by 120 min. ACTH and FSH accounted for an initial depression of RNA synthesis which, however, returned to normal 30 min after treatment. Remarkably, while the chemically similar hormones acted differently, insulin and glucagon showed the same trend of positive and negative influence, respectively.