Series of analytic experiments are presented that explore possible physiological mechanisms for the control of cardiac rate by nutritional intake in the pre-weanling rat. The essential properties of the nutrient and the first site of action were studied by using fluids of different pH, osmolality and chemical composition administered intravenously as well as intragastrically. Several probable effector pathways were explored: neuroendocrine (adrenal medullary and adrenocortical, thyroid), cholinergic and adrenergic. Pharmacological blocking agents, surgical removal of glands, replacement hormones and spinal cord trasaction were utilized. Afferent pathways such as vagus and splanchnic systems were approached surgically and the gastrointestinal hormones, histamine, insulin and glucagon, were studied by administration and pharmacological blockade. The evidence tended to rule out a number of possible mechanisms and pathways and to make it appear likely that nutrient acts initially at the gut wall, that the CNS then responds by increasing tone in the classical spinal cardioacceleratory pathways to the beta-adrenergic synapses of myocardium.

Adrenal Cortex Hormones↗

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Editorial: A functional, anterior hypothalamic defect in primary anorexia nervosa?

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Adolescent↗

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The relationship of small limb movements during REM sleep to dreamed limb action.

Ten adult subjects, selected for good dream recall and ability to produce spontaneously fine limb movements in the laboratory, reported their last dream experience after awakenings from REM sleep during various limb movement and no movement conditions. The reports were rated for amount and girdle location of dreamed actions by judges blind to the awakening condition. There was a significant correlation between the number of girdles moving before awakening and the amount of dreamed action. Also, when dreams from single girdle movement awakening conditions were examined, the girdle active before awakening was dreamed as moving to a significant degree.

Adult↗

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Age at maternal separation and gastric erosion susceptibility in the rat.

The development of susceptibility to immobilization-induced gastric erosions was studied in laboratory rats previously separated from their mothers at 15, 21 or 25 days of age. Early separation (day 15) produced animals whose maximum susceptibility occurred at a much younger age, generated a susceptibility curve over life that was the inverse of the curve for animals separated later and led to severe gastrointestinal hemorrhage as a common and distinguishing complication in younger rats. The pathogenesis of erosion formation in early separated rats may be unique in that, for that group only, the food deprivation component of the immobilization paradigm, when presented alone, also produced erosion of the glandular stomach, with hemorrhage.

Age Factors↗

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