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Biomedical subjects

K Hecht

Publications and source records attributed to K Hecht.

At least 145 records · Page 8Linked to original sources
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Stress hormones and sleep disturbances - electrophysiological and hormonal aspects.

In noise effect research often the awakening reaction is maintained to be the only important health related reaction. The main argument is that sleep represents a trophotropic phase ("energy storing"). In contrast to this awakening reactions or lying awake belong to the ergotropic phase ("energy consuming"). Frequent or long awakening reactions endanger therefore the necessary recovery in sleep and, in the long-run, health. Findings derived from arousal and stress hormone research make possible a new access to the noise induced nightly health risk. An arousal is a short change in sleeping condition, raising the organism from a lower level of excitation to a higher one. Arousals have the function to prevent life-threatening influences or events through activation of compensation mechanisms. Frequent occurrences of arousal triggered by nocturnal noise leads to a deformation of the circadian rhythm. Additionally, the deep sleep phases in the first part of the night are normally associated with a minimum of cortisol and a maximum of growth hormone concentrations. These circadian rhythms of sleep and neuroendocrine regulation are necessary for the physical as well as for the psychic recovery of the sleeper. Noise exposure during sleep which causes frequent arousal leads to decreased performance capacity, drowsiness and tiredness during the day. Long-term disturbances of the described circadian rhythms have a deteriorating effect on health, even when noise induced awakenings are avoided.

Arousal↗
PubMedDate not supplied

[Self-stimulation reaction in normotensive and hypertensive rats].

The part of noradrenergic mechanisms in self-stimulation (SS) operant behaviour was studied in rats. In all experiments systolic blood pressure (BP) in the tail artery was measured by means of photocells. It was found, that small doses of noradrenaline facilitate the SS, while high doses depress or stop it. The depressive effect is accompanied by a marked increase of BP. Effective blockade of beta-adrenoceptive structures by inderal suppresses SS, and the inhibitory effect is accompanied by a small decrease of BP. Suppressing effect of alpha-adrenoblocking agent, phentolamine, is even more pronounced, but is accompanied by a marked decrease of BP. Beta-agonist isadrin causes a marked facilitation of SS without changes of BP. It is suggested that positive reward in the lateral hypothalamus is due to a direct stimulation of beta-adrenoceptive noradrenergic neuronal elements. Chronic neurogenic hypertension is developed by an overloading of the higher nervous activity. In chronic hypertensive rats there is a pronounced suppression of SS. A transient fail of BP caused by injection of catapresan (hemiton) results in a temporary recovery of normal SS behaviour. It may be concluded that reduction of lever-pressing rate during acute and chronic neurogenic hypertensions is related to baroreceptor mechanisms. The role of the autonomic nervous system in SS behaviour is discussed.

Animals↗