Neurochemical changes following the administration of precursors of biogenic amines.

Male Wistar rats were injected intraperitoneally with either saline, L-trytophan, D,L-5hydroxytryptophan, L-tyrosine, L-DOPA or choline and killed by the near-freezing method 15 and 45 min after injection. The brains were removed, pulverized and acetylcholine, dopamine, norepinephrine, 5-hydroxytryptamine, aspartate, glutamate, glycine and γ-aminobuttyric acid wwere extracted and concurrently measured using previously reported methods. Compared to saline injected controls, some precursors not only resulted in changes in the specific neurotransmiter systems being pertubated, but also changes in the content of other neurotransmitters.     

Neurochemical changes in rat striatum and substantia nigra following drug administration

The effects of a number of drugs that deplete catecholamines or block their receptors were investigated on the levels of free amino acids and glutamate decarboxylase activity in rat striatum and substantia nigra, in an attempt to clarify the possible links between catecholamine and amino acid transmitter function. While none of the drugs tested were significantly active in the striatum, profound changes occurred in the substantia nigra. The data are discussed in relation to the possible mechanisms involved.     

Localization of biogenic monoamines in the dura mater of the rat brain

Quantitative and qualitative composition of catecholamines (noradrenaline and dophamine) and indolalkylamines (serotonin and tryptamine) and their localization have been studied in cells and neural fibers of the rat dura mater. Luminiscent-cytophotometric and electron microscopic methods have revealed two types of cells depositing biogenic monoamines. As demonstrate the experiments with rausedil injection, monoaminocytes of the first type (mast cells) contain predominantly indolalkylamines and a small amount of dophamine. Monoaminocytes of the second type (chromaffin cells) synthesize mainly serotonin and, perhaps, tryptamine. In adrenergic neural fibers only noradrenaline has been found to be present.     

Neurochemical changes associated with schedule-controlled behavior.

Studies of monoamine metabolites within the cerebrospinal fluid compartment have indicated that this approach may be useful in examining central metabolic changes in vivo. By combining the technologies of radioisotope chemistry, operant behavior control and modification, and brain perfusion with push-pull cannulas, we have been able to examine minute to minute changes in the disposition of radiolabeled monoamine transmitter candidates and their metabolites. These substances appear to co-vary with changes in complex behavior maintained by operant schedules of reinforcement and affected by changes in schedules or administration of psychotropic drugs. In agreement with other perfusion studies, we have observed changes in fractional distribution of radiolabeled urea, a so-called extracellular marker, along with shifts in monoamines; but the former appear more transient. These observations nevertheless support the concept of dynamic changes within the extracellular environment of the CNS that may be part of a hormone-like communicating system with functional significance. Furthermore, the presence of peaks and/or troughs, in perfusates of [14C]urea of similar substances should not be taken as a priori evidence for nonspecificity of the technic, since selective release or inhibition of release of monoamines can be shown with appropriate drugs that are thought to act through these aminergic systems. Destruction of catecholamine nerve terminals with 6-hydroxydopamine likewise attenuates the signal-locked release of radiolabeled norepinephrine by a conditioned stimulus after conditioning occurs. No such release is seen on presentation of the to-be-conditioned neutral stimulus in control or 6-hydroxydopamine treated rats. These initial studies indicate the availability of a powerful tool for the study of drug-neurochemical-behavioral interactions using subjects as their own controls for extended periods of time so that phenomena of plasticity, tolerance and dependence may likewise be examined.     

Histochemical localization of biogenic monoamines in the cephalic ganglia of Octopus vulgaris

Formaldehyde-induced fluorescence in the cephalic ganglia of Octopus is distributed in a systematic manner which correlates well with the known quantitative distribution of these substances in the various lobes. Fluorescence is associated with certain neuronal perikarya, e.g. those in the superior buccal lobe, and with particular nerve fibre tracts and systems of terminal varicosities, e.g. those relating to the mediation of ‘taste’. The peduncle lobe shows a pattern of fluorescence associated with the ‘spine’ which is also exhibited by structures within the basal lobes which have recently been found to possess striking cytoarchitectural similarities to the peduncle lobe.     

Histochemical localization of biogenic monoamines in the posterior salivary glands of octopods

Tubules of the octopod posterior salivary gland are lined by two distinct epithelia, type A and B of which type A is predominant. A positive chromaffin reaction is given only by a small proportion of columnar cells of the type A epithelium, and is apparently associated with the large (3mu) cytoplasmic granules of these cells. A similar proportion of type A columnar cells exhibit formaldehyde-specific fluorescence which is not reduced by reserpine in doses which reduced fluorescence in the optic lobes and in fibres associated with myoendothelial cells investing the posterior salivary gland tubules.     

Neurochemical changes following kainic acid lesions of the nucleus accumbens: implications for a GABAergic accumbal-ventral tegmental pathway.

Unilateral injection of kainic acid into the nucleus accumbens of the rat produced moderate depletions of the GABA synthesising enzyme glutamic acid decarboxylase in the accumbens and ventral tegmental area, but failed to alter these parameters in the striatum or substantia nigra. Similar injections into the striatum produced opposite effects to those seen following accumbens injections. These results are consistent with a GABA-ergic accumbal-ventral tegmental pathway analogous to the well defined striatonigral pathway. However, alternative interpretations, possibly in terms of a non-GABAergic accumbal-ventral tegmental pathway modulating GABA interneurons intrinsic to the tegmentum, must be considered.     

Time-dependent changes in brain biogenic amine dynamics following castration in male rats

—Alterations in whole-brain and hypothalamic levels of serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), norepinephrine (NE), dopamine (DA) as well as the turnover rates of NE and DA of adult male rats were analysed fluorometrically at either 3 weeks or 6 weeks following castration. Significant increases were observed in whole-brain (minus hypothalamus) 5-HIAA levels and hypothalamic DA levels, fractional rate constants and utilization rates at the 3 but not the 6 week intervals. Elevated levels of 5-HT were observed at both time intervals while an increase in whole-brain DA was seen only at the 6 week interval. Whole brain NE turnover rates of castrated animals did not differ significantly from those of sham-castrate control animals at either test interval. However, a tendency toward increased hypothalamic NE turnover rates was seen in the castrated animals. These biochemical changes resulted in decreased NE/5-HT and DA/5-HT ratios for the castrate rats as compared to controls. The results are discussed in relation to emotional and aggressive behavior and are interpreted as being consistent with the hypothesis purporting an inhibitory role for 5-HT and excitatory role for NE and DA in sex-specific behavior patterns including aggression.     

Ultrastructural changes in the developing chicken cornea following caffeine administration

Caffeine is one of the most frequently consumed psychoactive substances. It has been known for many years that caffeine at high concentrations exerts harmful effects on both women's and laboratory animals' fertility, moreover it may impair normal development of many organs in the prenatal period. So far there have been few studies performed that demonstrate teratogenic effects of caffeine on structures of the developing eye, particularly the cornea. The aim of the study was to show ultrastructural changes in the developing cornea, as the effect of caffeine administration to chicken embryos. The experimental materials were 26 chicken embryos from incubated breeding eggs. Eggs were divided into two groups: control (n=30) in which Ringer liquid was administrated, and experimental (n=30) in which teratogenic dose of caffeine 3.5mg/egg was given. In 36th hour of incubation solutions were given with cannula through hole in an egg shell directly onto amniotic membrane. After closing the hole with a glass plate and paraffine, eggs were put back to incubator. In 10th and 19th day of incubation corneas were taken for morphological analysis with a use of electron microscopy. Administration of caffeine during chicken development causes changes of collagen fibers of Bowman's membrane patterns and of the corneal stroma but it also changes proportion of amount of collagen fibers and of the stromal cells.