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Biomedical subjects

K Hecht

Publications and source records attributed to K Hecht.

At least 73 records · Page 4Linked to original sources
PubMed1980

Effects of a substance P-analogue on blood pressure and avoidance learning of rats with spontaneous hypertension.

A shortened and modified eledoisin-hexapeptide sequence (Lys-Phe-Ile-Gly-Leu-MetNH2) was tested for their action on avoidance learning and blood pressure of rats with spontaneous hypertension (SH-rats) and intact Wistar rats. Both groups were 10, 14, and 26 weeks of age. Disorders of avoidance learning and elevation of blood pressure were likely to aggravate along with growing age of SH-rat. The used eledoisin-hexapeptide sequence is related to the essential C-terminal pentapeptide sequence of Substance P (SP). After injection of the used hexapeptide at doses of 250 microgram/kg intraperitoneally disorders in avoidance learning were completely eliminated from ten-week SH-rats or conditionally for SH-rats aged 14 and 26 weeks. Elevated blood pressure in SH-rats aged 26 weeks was reduced by the hexapeptide from 220 Torr to approximately 190 Torr. Blood pressure in SH-rats aged 14 weeks, originally about 180 Torr, was almost unaffected by the hexapeptide. Blood pressure went up from about 150 Torr to 190 in ten-week-old Sh-rats. A hypothesis was made about the mode of action of Substance P and related peptides.

Animals↗
PubMed1980

[Effect of a substance P analog on sleep deprivation].

The injection of 250 microgram/kg SP-analogue (Lys-Phe-Ile-Gly-Leu-MetNH2) is able to restore the reduced or disturbed delta activities and paradoxical sleep periods of the sleeping EEG in chronically stressed rats. Thus it has been proved that Substance P, which we would like to term as an ,,regulatory peptide" (equal to regulide) has a modulating function.

Animals↗
PubMed1979

Conditioned-reflex learning of normal juvenile and adult rats exposed to action of substance P and of an SP analogue.

The actions of both Substance P, a potential neurotransmitter or modulator and of a shortened analogue on learning and memorizing processes are reported in this paper. Sixty male rats, aged 22, 14, and 10 weeks, were exposed to Substance P (Arg-Pro-Gln-Gln-Phe-Gly-Leu-MetNH2) and to a shortened hexapeptide analogue (Lys-Phe-Ile-Gly-Leu-MetNH2), doses being 250 microgram/kg and 500 microgram/kg, to test their action upon learning and memorizing processes, such as acquisition, retention, and ecphoration, by means of a conditioned-reflex locomotor defense method. Response time of all three age groups as well their retention and ecphoration were normal under the impact of hexapeptide. The effects of Substance P were decline of retention in juvenile animals (10 weeks of age) and coupling between the processes of central-nervous afference synthesis, on the one hand, and the efference integral related to motoricity, on the other, in both juvenile and adult animals. A retention test was conducted and showed that discontinuation of application of either peptide over 4 d was followed by complete inhibition of ecphoration. Learning and memorising processes were restorable by reapplication of the peptides. These findings were defined as "state-dependent learning". Only slight variation under the impact of both Substance P and the analogue was recordable by non-invasive measurement of systolic blood pressure.

Aging↗
PubMed1979

Action of substance P on neurotico-hypertensive rats.

The action of an eledoisin-hexapeptide analogue (EH) upon learning and memorising processes of 48 male Wistar laboratory rats aged between 5 and 6 months was studied and is reported in this paper. The animals suffered from neurogenic hypertension which had been experimentally induced by applying emotional stress. A comparison between the action of EH (Lys-Phe-Ile-Gly-Leu-MetNH2) and that of Substance P (Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-MetNH2) on conditioned-reflex learning in the intact rat had been reported by the authors in one of their previous papers [7]. The following results were obtained with regard to EH and its action upon rats with neurogenic hypertension. The learning process was favoured, as it had been by 2 or 3 weeks of exercise. Defective learning and memorizing process as well as impaired behavioural patterns, interpreted as neurotic phenomena, were normalized by doses of 250 microgram/kg and 500 microgram/kg. Blood pressures were reduced, depending on dosage. The action of the EH analogue used on the central nervous system was stronger than that on blood pressure. Discontinuance of peptide application was followed by the phenomenon of "state-dependent learning". The results are likely to suggest possible involvement of such peptide sequences in the regulation of processes which are relevant to the whole. That effect is of particular interest, as Substance P is under discussion as a transmitter or modulator in mammals.

Animals↗
PubMed1978

[The preprogramming of behavior patterns by changing the neurotransmitter metabolism in the early postnatal ontogenesis of albino rats].

Changes in neurotransmitter concentrations, which are brought about by the administration of neurotropic pharmaceuticals to albino rats at the time of differentiation of the brain, may have a lasting effect upon the reactivity and adaptability of adult animals to environmental factors and give rise to specific patterns of behavior. 1. Pargyline, when administered neonatally, resulted in a reduction of learning power, decrease in the power of retention, as well as reduction of the decision-making ability. 2. Reserpine gave an improvement of learning power, but simultaneously decreased both the power of retaining what had been learnt and the decision-making ability. 3. Pyridostigmine gave a marked improvement of adaptability which was evidenced in higher learning power, greater retentiveness, and better decision-making ability.

Animals↗
PubMed1978

[Learning and memory processes during postnatal ontogenesis in rats with spontaneous hypertension].

The examination of learning and memory processes by a conditional reflectory locomotor avoidance reaction on 8-, 10-, 12-, 14-, 16-, 20-, 26-, and 50-week-old rats with spontaneous hypertension (SHR Okamoto/Aoki) revealed, up to an age of 20 weeks, correlations between the height of blood pressure and learning and memory performance by analogy with parameters of the hydrocarbon metabolism [1,2]. Three stages were observed: Stage I: Juvenile animals (8--10 weeks) with mean systolic blood pressure values of 150 to 170 torr showed a comparatively low restriction of learning and memory processes. Stage II: In adult animals (12--20 weeks) with mean systolic blood pressure values of 180 to 210 torr learning was inhibited by about 50%, while retention of memory was completely disturbed. Stage III: In old animals (26--50 weeks) with mean systolic blood pressure values above 200 torr the faculty to learn a conditional avoidance reflex was virtually lost. Destruction or blockage of hypothalamic behavioral substances are assumed to cause the derangement of learning and memory processes in spontaneously hypertensive rats.

Aging↗
PubMed1976

Hypertension in adult rats treated neonatally with angiotensin.

Rats treated neonatally with angiotensin showed labile hypertension in adulthood. This finding may suggest a permanently changed responsiveness of a central nervous controller of the cardiocirculatory system caused by angiotensin-induced hypertension during brain differentiation.

Angiotensin II↗
PubMed1976

[Asymmetric function of the pes hippocampi in experimental stress-induced arterial hypertension of albino rats].

Relations between a unilateral lesion of circumscribed structures of the Pes hippocampi on the one hand, and stress-induced blood-pressure and learning behaviour, on the other, were studied. An asymmetric functioning of the CNS was analyzed, in which unilateral exclusion of right-hand hippocampal structures stimulates processes of excitation, while lesion of left-hand structures causes prevalence of inhibitory processes. The resulting impairment of the emotional equilibrium potentiates the stress action's contribution to the development of arterial hypertension.

Animals↗
PubMed1976

[Use of various statistical procedures for the analysis of biorhythms (periodicities of conditional-reflex processes in the minute range) under emotional stress and physical exercise].

Periodicities of conditional-reflectory processes in the minute range were measured in albino rats kept under various conditions (emotional stress, exercise, normal stall maintenance) and analyzed by different statistical procedures. It was possible in this way to judge by selected parameters of periodical processes the intensity of loads and effects of exercise. The additional use of cluster analysis for scaling the biological effectiveness of different communicative relations of the organisms proved useful.

Animals↗
PubMed1976

[Diurnal dynamics of periodicities in conditional-reflex processes in the minute range].

Male adult albino rats living from the 6th week of their lives under conditions of artificial light-dark cycle (16 hrs light, 8 hrs dark) were used to study possible relationships between circadian sensitivity cycles and synchronization of dynamics and the frequency variability of periodicities of reaction times of conditional-reflectory processes with wavelengths in the minute range. The experiments have revealed differences at the time of the activity maximum and minimum of a circadian cycle in the studied parameters of the minute rhythm (mean level of oscillation, mean amplitude, length of period and coupling). In the dark phase (activity maximum) there prevailed an increased level of central-nervous excitation and a tendency towards a higher frequency and diminished coupling of minute periods. In the light phase (activity minumum) the animals showed a balanced level of excitation, reduced frequency and a rigid coupling of periodicities of conditional-reflectory events involved in the process. Relations are shown to exist between central-nervous processes and circadian sensitivity cycles. For the experimental practice it is concluded that the different times of the day should be accounted for in assessing the criteria of minute rhythm and in conditional-reflectory studies in pharmacology and toxicology.

Animals↗
PubMed1976

[Glucose tolerance of postnatally stress-sensitized albino rats following chronic emotional stress in adulthood].

Male albino rats were used to study the effect of electrical stimulation in the postnatal phase (day 1--15) leading to short-time convulsions and cyanosis lasting about 10 min in 5-month-old animals upon the development of glycemic dysregulation induced by emotional stress. The studies involving i.p. glucose administration show that a 3-week stress influence on postnatally stimulated animals caused heavier changes of glycemic regulation than with non-pretreated animals. These results suggest a stress sensitization occurring in the postnatal phase and are discussed in connection with the "stress-sensitive risk personality" by R. BAUMANN. Further studies have shown that the postnatal stress sensitiveness is reversible and cannot only be compensated by a rest period of several weeks but may even cause stress resistance on renewed stressing for three weeks.

Animals↗
PubMed1976

[The role of uncertainty in the conditioned-reflex learning behavior for selected cardiovascular functions].

As a contribution to quantitative analysis of exogenous stress action, the role of probability learning (probability stress, probability affirmation) for selected cardio-vascular functions was studied in 25 albino rats and 8 dogs. It has been shown in the rats learning with probability stress that a dependence exists between stress probability, on the one hand, and conditional-reflectory processes and systolic blood pressure rise, on the other, that is, the pathogenic action of probability stress increases from a probability of p = 1.0 to p = 0.5. An analogous picture was found with the probability affirmation being applied in dogs. While a probability affirmation with p = 1.0 promoted adaptational processes, a value of p = 0.5 led to experimental neurosis, tachycardia and ECG alterations. The results obtained are discussed in context with the information entropy and information theory of emotions.

Animals↗
PubMed1976

Teratopsychogenetic effects apparently produced by nonphysiological neurotransmitter concentrations during brain differentiation.

In male rats treated with pargyline, reserpine or pyridostigmine during neonatal life significant permanent changes of sexual behaviour and conditioned learning behaviour were observed in juvenile and/or adult life. Male sexual activity and learning capacity were permanently decreased in neonatally pargyline- or reserpine-treated animals, but permanently increased in neonatally pyridostigmine-treated rats. These findings suggest that nonphysiological concentrations and/or turnover rates of neurotransmitters, if produced during a critical period of brain differentiation, are able to induce lifelond effective behavioural changes, i.e. teratopsychogenetic effects.

Animals↗