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Biomedical subjects

K Hecht

Publications and source records attributed to K Hecht.

At least 37 records · Page 2Linked to original sources
PubMed1986

Postnatal administration of L-dopa normalizes hypoxia-induced long-term changes in dopamine release from striatum slices and in avoidance learning.

Newborn rats exposed to a mild chronic postnatal hypoxia always displayed at the age of 2-3 months an increased fractional efflux rate of dopamine (DA) from striatum slices combined with a decreased capacity for learning and retention. The protective effect of the administration of L-DOPA on these long-term changes was tested by the injection of L-DOPA 5-30 min prior to the beginning of daily exposure to hypoxia. L-DOPA administration during postnatal hypoxia prevents in a dose dependent manner the long-term effects of postnatal hypoxia as described. This finding supports the hypothesis that long-term changes in DA release and in behaviour due to early postnatal hypoxia may be brought about by changes in the DA-metabolism during a critical period of development.

Animals↗
PubMed1986

The vulnerable period of perinatal hypoxia with regard to dopamine release and behaviour in adult rats.

The relations between a perinatal exposure schedule and the outcome of dopamine (DA) release from striatum slices on the one hand and behaviour on the other, were studied in order to identify the vulnerable period. A mild chronic postnatal hypoxia (2nd-10th day of life) induces long-term effects on the DA release rate (FER) from striatum slices. A 10 h daily exposure to hypoxia for 5 days (2nd-6th day of life) induces the same long-term effects. Adult rats exposed to hypoxia (pO2 8.6 kPa) for 16 h respond with a drastic decrease of FER of DA. Exposure to early postnatal hypoxia prevented this drastic decrease of FER of DA when adult rats were again exposed to hypoxia. 3 ten h periods of hypoxia within the first 10 days of life were enough to the long lasting effects. Prenatal hypoxia as well as hypoxia during the adolescent period did not show any long-term effects on the dopaminergic system. Alterations in behaviour (decreased learning capacity as well as decreased reaction to stimuli after prolonged stress in adulthood) were found after 3-9 days of hypoxia between the 2nd and 10th day of life.

Aging↗
PubMed1985

Influence of substance P on nociception and stress.

In 1980 Oehme and co-workers [11] reported that Substance P (SP) has a dual effect on nociception, which is related to the pain threshold before SP administration. Our recent results showed that the N-terminal part of the SP sequence may be important to the hyperalgesic action, and the C-terminal part to the analgesic action of this peptide. The hyperalgesic effect of SP (and N-terminal fragments of SP) seems to be related to the "anti-stress" effect which was first demonstrated by Hecht and co-workers [5] and Oehme and co-workers [12]. Interaction of SP with opioid peptides could be the common reason of both the "anti-stress" effect and the hyperalgesic activity of SP.

Analgesics↗
PubMed1984

Long-term effects of psychoemotional stress and tread-mill exercise on the microcirculatory system of rats.

To answer the question of whether the increased intensity of tonic or of relaxing influences acting on the microcirculatory system predominate in various chronic psychoemotional stress situations and/or after long-lasting and intense tread-mill exercise, the left-ventricular wall of the heart and the skeletal muscle or pancreas of 49 experimental and 33 control animals were investigated, using a new histomorphometric method. Chronically stressed rats showed an increase of wall thickness in microvessels documenting a long-term increase of contractile performance of wall cells for the development and maintenance of an increased contractile tone; however, there were quantitative differences depending on the manner, intensity, and duration of stress. The opposite occurred in rats exercised by a tread-mill over 6 months, 3 h per day, demonstrating the morphological correlative of metabolic long-term autoregulation. An aversion stress applied simultaneously on these animals effectively antagonized the mentioned effects of exercise.

Animals↗
PubMed1983

Long-term effects of early postnatal nutrition on subsequently body weight gain, emotionally and learning behaviour in male rats.

Male rats have been reared as litters of 2 pups (group A) or 12 pups (group B) during the first 3 weeks of life. Males of group A exhibited higher body weights from day 10 to day 430, reached puberty at earlier age and showed lower emotionality as well as diminished learning capability and decreased memory capacity in adulthood as compared to males of group B. Furthermore, adult males of group A developed an increased ratio of insulin to glucose serum concentration at 90 minutes after glucose administration.

Animals↗
PubMed1983

[Effect of substance P on blood pressure in rats, with and without hypokinetic stress].

The effect of substance P (SP) on blood pressure was studied in normotensive rats and in rats with hypokinesia-induced hypertension. To characterize the SP effect, the influence on the blood pressure value, intra-individual variation and interindividual changes was investigated. Whereas SP corrected the hypokinesia-induced changes (increased blood pressure, increase in the intra-individual blood pressure variations) in the stressed animals, no SP effect was observed in the normotensive control rats. These findings are discussed with a view to the assumed ability of SP to act as a regulatory peptide (regulide).

Animals↗
PubMed1983

[Significance of the time of administering substance P on learning and memory in rats].

We studied the influence of time and period of application of substance P (SP) on type and size of the effects on learning in Wistar rats. Treatment with SP before acquisition training had a fascillitating effect on learning. If SP was applied from the 1st or 3rd d of acquisition training there was no effect; if given from the 2nd d an inhibition was found; if given from the 4th d the consolidation of memory became finished. We found during the inhibition of exploration if SP was given acquisition training only (and no longer during the retention test). Some possible explanations of these differing effects of SP are discussed.

Animals↗
PubMed1983

[Asymmetrical content of dopamine-beta-hydroxylase and phenylethanolamine-N-methyltransferase in the adrenals of spontaneously hypertensive and normotensive Wistar-Kyoto rats].

The enzymatic activities of dopamine-beta-hydroxylase (DBH) and phenylethanolamine-N-methyltransferase (PNMT) were determined in adrenals of spontaneously hypertensive rats (SHR) and controls of the Wistar-Kyoto-strain (WKY) of different ages. In SHR of all examined age groups (10, 14 and 26 weeks) lower enzyme activities were found than in WKY rats of the same ages. That was more evident for PNMT than for DBH, SHR show a clear asymmetric distribution or PNMT with higher values in the left adrenals. This concerns 10, 14 and 26-week-old animals. An asymmetric distribution of DBH with higher values in the right adrenals were shown only in 14 and 26 weeks old rats. The asymmetric distribution was generally more obvious in SHR. This fact could be related to changes in the control of the connections between hypophysis and adrenals during development of hypertension.

Adrenal Glands↗
PubMed1982

Relation of substance P to stress and catecholamine metabolism.

Most research on substance P deals with its presumed function in the nervous system. Both excitatory and inhibitory actions have been observed in pharmacological studies. For example, substance P has a dual action on nociception in mice: it produces analgesia or hyperalgesia, depending on the dose and on the individual sensitivity to pain. This is interpreted to mean that substance P is capable of normalizing responsiveness to pain. Thus substance P could be classified as a regulatory peptide, or 'regulide'. A similar normalizing action of substance P was found in stress-induced disorders of sleep, behaviour and blood pressure in rats. The mechanism of this normalizing action is not yet clear. The decrease in activity observed for dopamine beta-hydroxylase and phenylethanolamine N-methyltransferase in adrenal glands of rats treated with the peptide may serve as a preliminary hypothesis.

Adrenal Glands↗
PubMed1982

[Effect of substance P on dopamine-beta-hydroxylase and phenethanolamine-N-methyltransferase in the adrenal glands of rats].

Resulting from literature data concerning interactions between catecholamines and Substance P (SP) the influence of SP on the activity of dopamine-beta-hydroxylase (DBH) and phenylethanolamine-N-methyltransferase (PNMT) was studied in rat adrenals. Intraperitoneal application of SP (500 micrograms/kg) to male Wistar rats 15 minutes before decapitation induced a decrease of PNMT activity in the adrenals, while DBH activity remained unchanged. After incubation of adrenals with SP (10(-6) mol/l) a decrease of activity of both PNMT and DBH was observed. The experimental results are discussed in connection with a normalizing function of SP during stress induced disorders.

Adrenal Glands↗
PubMed1982

Action of substance P and an SP-hexapeptide analogue on avoidance learning in rats.

The effects of Substance P (SP) (Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-MetNH2) and of a SP hexapeptide analogue (SP-A) (Lys-Phe-Ile-Gly-Leu-MetNH2) on active avoidance learning were investigated in spontaneously hypertensive rats (SHR) and Wistar rats. Active avoidance learning was slower in SHR than in Wistar rats. SP-A "normalized" the slower active avoidance learning in SHR, whereas SP did not. Some possible causes of this difference as well as the mechanism of the normalizing effect of SP-A are discussed.

Animals↗