The effect of AVP and DGAVP on the exploratory activity of rats.

The effects of [8-L-arginine] vasopressin (AVP) and desglycinamide [8-L-arginine] vasopressin (DGAVP) were tested on the exploratory activity of adult male rats in a novel environment. The inherited individual differences in the non-specific excitability level of the animals were ascertained prior to the drug administration and the rats were then distributed evenly into the experimental groups. One half of each groups contained the less excitable and the other the more excitable animals. The peptides or saline were injected every other day--altogether 4 times--in a dose of 5 micrograms/kg/ml subcutaneously, 40 min before starting the experiments. The exploratory activity in the novel environment was observed for 15 min. AVP and DGAVP, which differ in their peripheral endocrine activities, had opposite effects on the behavior in a novel environment: AVP, with its wide spectrum of peripheral effects, decreased the exploratory activity, whereas DGAVP, with minimal peripheral effects, increased the exploratory activity slightly. This basic response to the administration of peptides was influenced by the type of inherent non-specific excitability level. The depressive action of AVP was more pronounced in the more excitable rats, whereas DGAVP significantly stimulated the less excitable animals. It is concluded that the inhibitory effect of AVP is mainly due to its peripheral endocrine, especially hemodynamic, effects, whereas DGAVP is supposed to increase arousal, which is responsible for differences in the animals' performance with regard to their inherited non-specific excitability levels.

The role of the time dimension in the analysis of spontaneous behaviour.

The reflex approach to the study of behaviour elaborated, thanks to the Pavlovian school, a successful style of experimentation. The study of spontaneous behaviour lacks such a sophisticated experimental paradigm. It seems that in the future paradigm the time dimension will play a decisive role as in physics. If the spontaneous behaviour is registered for a sufficiently long period and in sufficient details, i.e. if each action is exactly located in time, the analysis of time intervals reveals a typical, s.c. activational rhythm, which enables the prediction of spontaneous actions. Examples of the broad applicability of the hierarchical structure of the activational rhythm in animal studies and in human normal and abnormal behaviour are being presented.

[Contamination of adipose tissue of slaughter animals with chlorinated insecticides and hexachlorobenzene in the Central Bohemian Region]. / Kontaminace tukových tkání jatecných zvírat chlórovanými insekticidy a hexachlorbenzenem v oblasti stredních Cech.

Residues of some chlorinated pesticides (hexachlorobenzene, lindane, DDE, DDT) were detected in adipose tissues of commercially important animals in Central Bohemia; the method of gas chromatography and an electronic detector were used. Residues of chlorinated hydrocarbons were detected in all examined samples, the hexachlorobenzene concentration was explicitly higher than the concentrations of DDT and lindane. The hexachlorobenzene residues occurred locally. The hexachlorobenzene concentrating detected in the adipose tissues of cattle and pigs were higher than in some European countries; the DDT and lindane concentrations were at the same level.

[Pathogenicity of aerobically sporulating microorganisms: Bacillus cereus]. / Patogenita aerobne sporulujících mikroorganismu: Bacillus cereus.

The pathogenicity of the metabolites of B. cereus was determined by bioassays with white mice, chick embryos, rabbits, and kittens. Cell-free filtrates of the cultures of several strains of B. cereus were used for application; in the mice the application was done i. v., i. p. and p. o., in the chick embryos via the allantoic sac, in the kittens p. o. and i. p., in the rabbits via tied-up sections of the small intestine by the loop-test method. It was revealed that some strains of B. cereus produced substances of exotoxin nature under suitable conditions. White mice and chick embryos were the best materials for their detection.

[Pathogenicity of aerobically sporulating microorganisms: Bacillus subtilis]. / Patogenita aerobne sporulujících mikcroorganismú: Bacillus subtilis.

Bioassays were made on white mice and rats to find the potential pathogenicity of B. subtilis and its metabolites. The peroral and intraperitoneal application of several strains of B. subtilis to white mice did not cause any changes either in the behaviour or health condition of the animals until the first to seventh day after test. B. subtilis cultures or cellular suspensions on the one hand and non-cellular filtrates of cultures represented by the B. subtilis metabolism products on the other hand were given to the animals. No changes in the health condition of the mice and rats were observed when feed artificially infected with B. subtilis was fed. Dissection did not reveal any macroscopic changes on the organs of the abdominal and thoracic cavity. Cultures from the individual body organs (liver, spleen, kidneys, parts of the small and large intestines, stomach) perorally infected with B. subtilis showed the presence of the microbe only in parts of the digestive tracts.

The analysis of habituation.

Using the "method of continuous data" a detailed, quantitative description of the "action-program" of rats introduced into new environment make it possible to derive indices of the intensity of behavior which correlate closely with hippocampal "theta" activity. Using these indices a mathematical analysis of the course of habituation was attempted. Both uninterrupted and interrupted habituation can be divided into two parts: the activation and disactivation (habituation) curves. The theoretical habituation curve may be represented by a negative (usually) exponential growth function on which intrinsic damped oscillations with exponentially increasing wavelengths and decreasing amplitudes are superimposed (Fig. 11). The activation curve has the inverse characteristics (Fig. 15). The course of positive learning seems to be intimately related to the activation curve. Since the dependence of both the rate of habituation and the rate of discrimination learning on the individual excitability level are of the same nature (inverted U-shaped curves), habituation can hardly be accepted as the simplest kind of learning. For habituation to occur, intervals between stimuli are critical; novelty or absence of reinforcement may be secondary.