Dynamic interactions of evoked potentials in a polysensory cortex of the cat.

Interactions of acoustic and somatosensory evoked potentials were studied in the anterior suprasylvian gyrus of the cat. Two kinds of interaction could be observed: occlusion or facilitation. In most cases occlusion was observed. The interactions showed dynamic changes and were susceptible to different kinds of influences. After having determined the control values of interaction over a period of several minutes, reversible enhancement of occlusion was observed after synchronous activation of the acoustic and somatosensory inputs with 2 Hz frequency. The same effect could be observed during stimulation of the mesencephalic reticular formation with 200 Hz frequency. The interactions could also be influenced by amphetamine and gamma-glutamyltaurine, known as drugs capable of influencing the arousal level of the brain. During treatment with amphetamine the interaction was shifted in the facilitatory direction. The antagonists of amphetamine (haloperidol and reserpine) prevented this effect. The authors suggest that the interactions of acoustic and somatosensory responses are mediated by interneurons (inhibitory and/or excitatory) and particular stimulus situations and drugs are able to modify the equilibrium between excitatory and inhibitory subsystems.

Formation of gamma-glutamyl-taurine in the rat brain.

After intraventricular administration on 14C- or 3H-labelled taurine, gamma-glutamyl-taurine was detected in the protein free extract of rat brain using a combination of ion exchange chromatography, electrophoretic separation and thin-layer chromatography. Under in vitro conditions gamma-glutamyl-transpeptidase (EC 2.3.2.2.) prepared from rat brain catalyses the formation of gamma-glutamyl-taurine from taurine and glutathione or gamma-glutamyl-p-nitroanilide. The enzymes of the gamma-glutamyl cycle are presumed to be responsible for the in vivo metabolism of this dipeptide.

Inhibition of the formation of protein storage granules by glutaurine in the larval fat body cells of Mamestra brassicae (Insecta, Lepidoptera).

Correlative changes in the protein contents of haemolymph and fat body and the accumulation of protein storage granules in the fat body cells of Mamestra brassicae were investigated during the last larval stage in normally developing larvae and following administration of glutaurine (1 X 10(-4) mg/g body weight). The protein content of the haemolymph of untreated larvae increased up to the 4th day of the stage, declined during days 5 and 6, and increased again before pupation. In the glutaurine-treated larvae the amount of proteins in the haemolymph was as high as in the controls during the first four days but continued to rise up to the end of the stage. The protein content of the fat body started to increase from the 3rd day and heavy accumulation of protein storage granules in the cells of fat body was observed on the 5th and following days. The protein content of the fat body of glutaurine-treated larvae remained at a low level and the protein storage granules were absent in the cells. The inhibition of the selective uptake of haemolymphatic storage proteins by fat body following glutaurine treatment is suggested.

Radioprotective effect of a protein free parathyroid extract on the mitotic index of rat bone marrow cells.

The protective efficacy of an orally administered bovine protein-free parathyroid extract (PF-PTE) was studied on rat bone marrow cells in vivo with the mitotic index after 850 R irradiation. A remarkable decrease was found in the mitotic activity of bone marrow cells after irradiation in the non-protected animals. However, in the animals treated with PF-PTE after irradiation, a significantly smaller decrease and a faster recovery were found in the mitotic activity of the bone marrow cells.

Effect of glutaurine and its derivatives and their combinations with radiation protective substances upon irradiated mice.

The radiation protective effects of glutaurine (gamma-L-glutamyl-taurine, Litoralon), and of some of its derivatives, as well as of their combinations with substances of the amino-alkyl-thiol group, have been investigated in mice. The results suggest that glutaurine possesses a radiation protective effect in animals irradiated with LD50/30 of roentgen rays and 60Co gamma rays. The compound has a favourable effect also when administered after irradiation. Its protective effect is especially marked in case of prolonged irradiation. Among the combinations best results were obtained by its simultaneous administration with subminimal doses of AET or cystamine. Some of its derivatives also exhibited considerable protection against irradiation with roentgen rays.

Radioprotective effect of a protein free parathyroid extract.

The radioprotective effect of a bovine protein-free parathyroid extract was studied in rats, being administered orally after irradiation. A significant increase in survival was found after treatment compared to conrols. It is assumed that the extract contains a new, probably as yet unknown bioactive agent responsible for the radioprotection.

Effect of protein-free parathyroid extract (PF-PTE) and gamma-L-glutamyl-taurine (glutaurine) on X-ray induced hyperglycaemia in the rat.

The protein-free parathyroid extract (PF-PTE) and gamma-L-glutamyl-taurine (glutaurine) produced mild hypoglycaemia in rats. Treatment with PF-PTE or glutaurine prevented the development of hyperglycaemia induced by X-ray whole body irradiation with 154.8 or 219.3 or 258.0 mC/kg doses. The plasma IRI values did not change following treatment. It is supposed that glutaurine acts by its antagonistic effect on glucocorticoids but its regenerating effect on the intestinal mucosa cannot be excluded either.

Anticonflict properties of the dipeptide Litoralon and of diazepam in rats.

The anticonflict properties of the anxiolytic diazepam and of the dipeptide Litoralon gamma-L-glutamyl-taurine and two of its analogues SZJ 3388, gamma-aminobutyryl-ethanolamine phosphate, and SZJ 3361, D-1-aminoisobutyrylethanolamine phosphate have been investigated in a "time-to-emerge" conflict paradigm in non-deprived rats. Diazepam, Litoralon and compound SZJ 3388 significantly decreased the "time-to-emerge" latency (TTE latency) in a dose-dependent manner versus saline- or vehicle-treated controls in doses between 0.05 and 0.50 mg/kg intraperitoneally. The analogue SZJ 3361 was inactive as regards the TTE latency, while the anti-histaminic promethazine lengthened the TTE latency in a dose-dependent manner. The number of irresolute responses was significantly decreased following administration of diazepam, SZJ 3388 and Litoralon and was positively correlated with the TEE latency-decreasing activity of these compounds. The data are discussed in terms of the benzodiazepine-like anxiolytic or anti-conflict properties of these dipeptides.

Gamma-L-glutamyl-taurine (Litoralon) affects conditioned taste aversion in rats.

The dipeptide gamma-L-glutamyl-taurine (Litoralon) reduced neophobia of rats at a dose of 5.0 mg/kg (i.p.) in a "one-bottle forced choice paradigm" for conditioned taste aversion (CTA), but did not significantly affect the rats' "memory" of intoxication following chronic treatment at doses of 0.05, 0.50 and 5.00 mg/kg (i.p.). Acute treatment with Litoralon (10-1000 micrograms/kg, i.p.) did not affect CTA checked in a "two-bottle test", when administered immediately following the unconditioned stimulus (LiCl injection). In contrast, when given 90 min prior to the retention test, the injection of Litoralon (50.0 micrograms/kg) and gamma-aminobutyryl ethanolamine phosphate (100 and 500 micrograms/kg) resulted in a significantly higher intake of saccharin solution by the rats. This effect is comparable to the action of diazepam tested in the same experimental procedure. The results support our hypothesis about the anti-conflict potencies of these dipeptides, exerted by reducing aversion of phobia and/or the anxiety level of the animals in the experimental situation.

The triiodothyronine antagonistic effect of gamma-L-glutamyl-taurine (litoralon).

A recently recognized bioactive substance of the parathyroid glands, gamma-L-glutamyl-taurine antagonises the metamorphosis enhancing effect of triiodothyronine. Shortening of the body-length of tadpoles is significantly delayed by the substance. The experimental results imply that it fulfills the role of a balance hormone.

Effect of litoralon (gamma-L-glutamyl-taurine) on the tail involution of tadpoles in vitro.

Litoralon (gamma-L-glutamyl-taurine), a newly discovered hormone of the parathyroid increases the involution of the explanted tail tip of Rana arvalis tadpoles in vitro, while it antagonizes significantly the similar effect of triiodothyronine. This finding, in accordance with the results of earlier in vivo experiments, implies a direct effect of Litoralon on the target tissues.

Effect of glutaurine on vitamin A and prednisolone treated thymus cultures.

The hormone of the parathyroid gland, Glutaurine (gamma-L-glutamyl-taurine) exerts on rat thymus cultures an effect synergistic with vitamin A and antagonistic to prednisolone. When applied in itself, it increased the vitality and macrophage reaction of thymus cultures.

Effect of glutaurine, a newly discovered parathyroid hormone on rat thymus cultures.

Under the effect of the recently discovered parathyroid hormone, gamma-L-glutamyl-taurine (Glutaurine) growth of thymus cultures increased in all tested age groups. Epithelial growth was prominent and signs of activation of the macrophage cells appeared. In cell cultures the nuclei and nucleoli increased in size.

Influence of protein free aqueous extract of parathyroid powder on serum vitamin A level in rats.

Administration of the protein-free extract of bovine parathyroid powder to rats resulted in a significant increase of the serum vitamin A level.

Effects of Litoralon (gamma-L-glutamyl-taurine) and its analogues on fear-motivated behaviour of rats.

The effects of a single post-trial intraperitoneal administration of the dipeptide Litoralon (gamma-L-glutamyl-taurine) and some of its analogues were tested on the passive avoidance latency of male and female Wistar rats. The avoidance latency was significantly decreased by Litoralon and gamma-aminobutyryl-ethanolamine phosphate but lengthened by DL-beta-aminoisobutyryl-ethanolamine phosphate. No differences were observed between the responses of immature male and female rats following Litoralon treatment. The observed inter-group differences in passive avoidance behaviour following dipeptide administration were also demonstrable in tests of the open-field activity of the animals examined immediately after the 24-hour retention test. The results are discussed on the basis of a central Litoralon effect on emotional arousal and the anti-conflict potencies of the dipeptide.

Effect of parathyroid extract and of glutaurine (gamma-L-glutamyl-taurine) on the manifestations of osteolathyrism.

BAPN-induced osteolathyrism in young and older male rats was examined for its responses to parathormone-free, gel-filtered bovine parathyroid extract (extract P) and to glutaurine (gamma-L-glutamyl-taurine), the latter being a hitherto unknown putative hormone isolated from bovine parathyroid and reproduced by synthesis. In case of the daily administration of 20 mg BAPN + 0.2 mg extract P/100 g body weight and of 40 mg BAPN + 0.2 micrograms glutaurine/100 g body weight, both substances were found to attenuate the manifestations of osteolathyrism, to a significant extent, without, however preventing their development completely. The significantly decreased Ca, P, chondroitine sulphate and chrondroprotein values due to the administration of BAPN showed a significant, or highly significant, increase for the cartilage in response to extract P, and for both cartilage and bone in response to glutaurine, without however, attaining the control values. Additional evidence has been furnished by the present study that synthetic glutaurine is equal to the parathormone-free, gel-filtered parathyroid extract (extract P) in its attenuating effect on experimental osteolathyrism.