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Biomedical subjects

H Kaba

Publications and source records attributed to H Kaba.

103 records · Page 6Linked to original sources
PubMed1983

Effects of estrogen on the excitability of neurons projecting from the noradrenergic A1 region to the preoptic and anterior hypothalamic area.

Estradiol benzoate administered to ovariectomized female rats significantly elevated the mean spontaneous firing rate and frequency of successful antidromic propagation into the somatodendritic spike and significantly reduced the strength of post-stimulus inhibition in presumed A1 noradrenergic neurons projecting directly to the preoptic and anterior hypothalamic area. The occurrence of both antidromic spikes and post-stimulus inhibition of the majority of these neurons was completely abolished by the injection of 6-hydroxydopamine but not by 5, 7-dihydroxytryptamine directly into the medial forebrain bundle.

5,7-Dihydroxytryptamine↗
PubMed1983

Influence of lesions in the limbic-hypothalamic system on adrenocortical responses to daily repeated exposures to immobilization stress in rabbits.

In order to elucidate the role of the limbic-hypothalamic system in the adrenocortical responses to repeated immobilization stress, the influences of daily repeated exposures of immobilization stress on the adrenocorticoid formation in adrenal slices of rabbits with lesions of various sites of the hypothalamus and limbic structures had been investigated. The experimental results obtained were as follows: (1) Lesions in periventricular arcuate nucleus (ARC) and ventromedial hypothalamus (VMH) decreased the rates of adrenocortical responses to the 1st immobilization exposure (exposure on the 1st day), but did not alter the rates of adrenocortical responses to the 4th immobilization exposure (exposure on the 4th day). (2) Lesions in stria-terminalis (ST) and dorsal fornix (FX) did not alter the rates of adrenocortical responses to the 1st immobilization exposure, but increased the rates of adrenocortical responses to the 4th immobilization exposure. (3) The adrenocortical responses to immobilization stress were completely abolished by the seven times repetition of exposures in each sham-operated group and in the animals with lesions of ARC and VMH, but in the rabbits with lesions of ST and FX the adrenocortical responses to immobilization stress were not abolished by the seven times repetition of exposures. (4) These results suggested that such basal medial hypothalamus participated in the mechanisms of adrenocortical responses to the 1st exposure of immobilization stress, but did not participate in the disappearance process of adrenocortical responses to immobilization stress by the seven times repetition of exposures. On the other hand, it might be supposed that the amygdala(AMYG)-ST system and dorsal hippocampus(HPC)-FX system do not participate in the mechanism of adrenocortical responses to the 1st immobilization exposure, but these limbic areas played some roles in the disappearance process of the adrenocortical responses to immobilization stress by the seven times repetition of exposures.

Adrenal Cortex↗
PubMed1983

Influence of lesions of the limbic-hypothalamic system on adrenocortical responses to daily repeated heat exposures in rabbits.

The effects of lesions in the basal medial hypothalamus and limbic structure upon the responses of adrenocorticoids formation in adrenal slices of rabbits to daily repeated heat exposures has been investigated. (1) The adrenocortical responses to heat exposure on the 1st day were decreased by lesions in the periventricular arcuate nucleus (ARC), ventromedial hypothalamus (VMH), stria terminalis (ST) and dorsal fornix (FX). (2) There were no effects of heat exposure on the 10th day upon the adrenocorticoid formation in either the sham-lesioned rabbits or the rabbits with the lesions of ARC, VMH and ST. (3) In rabbits with the FX lesions, the adrenocorticoids formation was significantly increased by heat exposure on the 10th day. (4) These results suggested that the basal medial hypothalamus, amygdala (AMYG)-ST system and dorsal hippocampus (HPC)-FX system participated in the mechanisms of adrenocortical responses to heat exposure on the 1st day, but only the HPC-FX system played some roles in complete disappearance process of adrenocortical responses to heat exposure by repetition of exposures.

Acclimatization↗
PubMed1982

Antidromic identification of neurons in the ventrolateral part of the medulla oblongata with ascending projections to the preoptic and anterior hypothalamic area (POA/AHA).

Seventy neurons in the ventrolateral medulla oblongata were antidromically activated by electrical stimulation of the preoptic and anterior hypothalamic area (POA/AHA) in female rats under urethane anesthesia. These identified cells were located within and adjacent to the nucleus reticularis lateralis and could be readily distinguished into at least two types of neurons, designated as "fast' and "slow' cells, on the basis of their waveform and conduction velocity.

Action Potentials↗
PubMed1978

[Nutritional evaluation of protein concentrates of beans (Phaseolus vulgaris) and lentils (Lens esculenta)].

The composition and nutritive value were determined in navy bean meal (Phaseolus vulgaris) and lentil meal (Lens esculenta), and in their respective protein concentrates obtained through extraction followed by isoelectric precipitation. Sulfur amino acids per gram of nitrogen were lower in the concentrates than in the meals, while there was no difference for lysine and threonine. The white bean protein concentrate had a lower biological value than the meal but better digestibility, although trypsin inhibitor concentration was unchanged. Digestibility greatly improved with heating but it did not increase beyond 81% even after autoclaving. Autoclaved samples supplemented with methionine reached a biological value of 83. The lentil protein concentrate also had a lower biological value than the meal but digestibility was high for both samples (91%) and remained unchanged after heating. Trypsin inhibitors were absent. After supplementing with methionine, a biological value of only 63 was obtained, due to the low level of tryptophan, the second limiting amino acid. In spite of the concentrates' lower biological value, it was proved that they equalled the meals' potential for complementing cereal, as their content in lysine and threonine is high. The concentrates have the additional advantage of allowing effective supplementation without increasing the legume-cereal ratio.

Amino Acids, Essential↗
PubMedDate not supplied

Synaptic mechanisms of olfactory recognition memory.

The complexity and inaccessibility of the mammalian brain prevent the localization and description of memory traces and the definition of the processes that produce memories. The model reviewed here is the olfactory recognition memory formed to male pheromones by a female mouse at mating. The memory trace has been localized to the reciprocal dendrodendritic synapse between mitral cells and granule cells in the accessory olfactory bulb. An increase in noradrenaline after mating reduces inhibitory transmission of gamma-aminobutyric acid (GABA) from the granule cells to mitral cells and induces an olfactory memory of pheromones present at mating. Recent work has shown that the activation of mGluR2, a metabotropic glutamate receptor, localized at granule cell dendrites suppresses the GABA inhibition of the mitral cells and permits the formation of a specific olfactory memory that faithfully reflects the memory formed at mating. This simple olfactory memory may provide an excellent model system with which to investigate the molecular mechanisms of the synaptic plasticity involved in learning and memory.

Animals↗
PubMedDate not supplied

Circadian rhythm of cardiac bradyarrhythmia episodes in rats.

It was investigated whether incidence of S-A block and A-V block (type I and II) observed in male Wistar rats shows a circadian periodicity. Under the 14/10 light-dark illumination schedule, circadian periodicity was demonstrated in the occurrence of bradyarrhythmias as well as slow wave sleep, paradoxical sleep locomotive activity and heart beats/hour. This circadian variation of bradyarrhythmia shows two major peaks. The highest peak coincides with the time zone immediately after the start of illumination, and the second peak coincides with the acrophase of the circadian variation in paradoxical sleep. The 25-h period of circadian rhythm of bradyarrhythmias was disclosed even under constant illumination. This circadian variation shows the disappearance of the early peak of two peaks observed in the light-dark schedule. These results show the existence of an endogenous circadian rhythm in bradyarrhythmias as well as in sleep-wakefulness and locomotive activity. This knowledge about the circadian rhythm of bradyarrhythmia must be incorporated into the effective treatment of arrhythmias.

Animals↗