PubMed Health⌕ Search

Biomedical subjects

A Markowska

Publications and source records attributed to A Markowska.

At least 19 recordsLinked to original sources
PubMed1992

Analysis of the preventive action of ACTH on dexamethasone-induced adrenocortical atrophy in the rat.

Adult female rats were treated for 4 or 6 days consecutively with dexamethasone (Dx; 100 micrograms kg-1 day-1) alone or with ACTH (100 micrograms kg-1 day-1) for 2, 4 or 6 days. After 2 days of ACTH administration, zona fasciculata cells increased in volume, and the blood concentration of corticosterone was raised. Basal corticosterone secretion by adrenal slices appeared to be enhanced by ACTH treatment only when calculating per adrenal pair (and not per unit wt of adrenals). A significant increase in the number of metaphase cells was observed after only 4 days of ACTH administration. It is suggested that (1) the first action of ACTH on Dx-suppressed rats is to induce the hypertrophy of adrenocortical cells; (2) the steroidogenic capacity of adrenocortical cells is directly proportional to their average volume; and (3) the stimulatory effect of ACTH on the proliferative activity of adrenocortical cells is subsequent to the stimulation of their specialized functions.

Adrenal Cortex↗
PubMed1991

Basal forebrain cholinergic system: a functional analysis.

This chapter has been organized empirically, focusing on the types of approaches that have been taken to understand BFCS function. This approach reflects the state of our knowledge about the behavioral and psychological functions of the BFCS. Considerable information has been gathered in the very short time that the BFCS has been the object of intense investigation. The results from the neurotoxic lesions and from the HACU studies provide some points of consistency and some puzzling differences. Both approaches to the study of basal forebrain function suggest that the MSA is involved in tasks that require spatial working memory; MSA lesions impaired choice accuracy, and HACU in the HIP was increased after performance. The pattern of results in simpler tasks is more difficult to interpret. In a left-right reference memory discrimination in a T-maze, MSA lesions did not impair acquisition or performance, whereas HACU in the HIP was activated during performance. This pattern of results suggests that although the MSA is engaged during this type of task, its activity is not necessary for normal performance. These, and other comparisons indicate the need for a systematic analysis of task demand (Olton, 1989b). Parametric manipulations of different task demands in a systematic fashion can indicate the extent to which the BFCS is involved in the function associated with each parametric manipulation. Ultimately, of course, the organization of this material should focus on particular psychological functions, rather than the techniques and procedures used to gather the information. Achieving this goal is going to require careful attention to the design of behavioral experiments so that definitive conclusions can be made about the extent to which the BFCS is involved in a given psychological function. A systematic application of task analysis can achieve this goal (Olton, 1986, 1989a, 1989b). For example, BFCS lesions in rats impair choice accuracy in spatial working memory tasks, and performance in these tasks engages the HACU system, at least in the HIP. If the spatial functions of this task involve the BFCS, then a nonspatial version of the task should produce a different pattern of results. If the spatial nature of the task is unimportant for BFCS function, then a nonspatial version of the task should produce the same results. By systematically changing one characteristic of the task at a time, the contribution of each component can be assessed.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗
PubMed1991

Comparison of the effects of neurotensin and ACTH on the pituitary-adrenocortical axis of dexamethasone-suppressed rats.

Neurotensin (NT) (12-48 micrograms/kg-1/day-1, for 2 days, s.c.), like ACTH (60 micrograms/kg-1/day-1, for 2 days, s.c.), counteracted the dexamethasone (Dx)-induced (120 micrograms/kg-1/day-1, for 4 days, s.c.) adrenal zona-fasciculata cell atrophy. NT notably raised, in Dx-suppressed rats, the plasma concentration of ACTH, which reached about that found after exogenous ACTH administration. However, at variance with ACTH, NT did not enhance either plasma corticosterone (B) level or B production by adrenal quarters in vitro. The conclusion is drawn that NT modulates the function of the rat pituitary-adrenocortical axis, by simultaneously stimulating hypophyseal ACTH release and inhibiting steroidogenesis at the adrenal level.

Adrenocorticotropic Hormone↗
PubMed1991

Individual differences in aging: behavioral and neural analyses.

Aged populations have remarkable variability in recent memory and cognitive mapping. Although some individuals may have substantial age-related impairments, others perform almost as well as young individuals. This paper reviews the relevant data on aged rats and indicates two challenges for biomarkers of aging. The first is to provide an appropriate quantitative description of these individual differences. The second is to use them effectively as markers for age-related changes in psychological functions and their neural substrates.

Aging↗
PubMed1988

Cue distinctiveness and response-to-change in scopolamine injected or hippocampal rats.

Our previous findings indicated that hippocampal lesions (H) or scopolamine' injections (Sc) affected stimulus information acquired by distant observation of the white-black T-maze arms (the passive test), but left the information intact when it was gained by T-maze exploration (the active test). Because this difference might reflect the attentional deficit in H or Sc rats, in the present experiment we attempted to investigate the effect of lowered distinctiveness of cues (dark grey vs black T-maze arms) on the performance of rats in the active test. A total of 75 rats were assigned to four groups: (i) damaged in the dorsal hippocampus (H); (ii) sham operated (C); (iii) scopolamine (Sc) injected (1.0 mg/kg i. p.) and (iv) saline injected (NaCL). Each group showed a significant preponderance of choices of the arm which was changed in brightness between the two consecutive trials, separated by 1 min break. The groups did not differ markedly among themselves in the percentage of changed arm choices (H group, 85 percent; C, 74 percent; Sc -72 percent; NaCL, 72 percent). This result indicates that H or Sc rats are able to perceive a slight difference of brightness and to retain it over a period of 1 min. Therefore, the different performance of H as well as Sc rats in the passive and active test, observed previously, cannot be accounted for by the attentional deficit hypothesis.

Animals↗
PubMed1987

[Preservation of the blood of slaughter animals by the non-diaphragmatic use of solidified carbon dioxide. II. Blood preservation-related changes in plasma proteins].

The preservation effectivity of slaughter animal blood for consumptive purposes was studies by a method of non-phrenic action with solidified CO2. The material for studies was full pig blood stabilized with sodium citrate. The course of the changes in plasma proteins caused by storage has been described by regression equations. It was found that non-phrenic contact of blood with solidified CO2 caused slight, statistically insignificant changes in plasma proteins. Moreover, the changes of the protein quality factors showed a smaller dynamics in the blood stabilized with solidified CO2 than in the control blood. The changes observed in the plasma proteins analysed were highly correlated with increasing parallel decomposition of morphological elements and the resulting increase of the level of hemocyte proteins in plasma.

Animals↗
PubMed1986

Behavioral effects after ibotenic acid, 6-OHDA and electrolytic lesions in the central amygdala nucleus of the rat.

Selective lesions of central amygdaloid neurons with ibotenic acid and electrolytic destruction of the nucleus both led to marked increases in open field activity and activity during passive avoidance conditioning. However, electrolytic lesions of both neurons and fibers resulted in the most pronounced passive avoidance impairments and it is suggested that this lesion effect should be attributed to a combined destruction of intrinsic neurons and neurons located outside the central amygdala nucleus. The 6-OHDA lesions resulted in no significant changes in the behavioral parameters under investigation or in plasma corticosterone levels. The lack of reduced corticosterone levels in any of the lesioned groups do not indicate that general fear arousal is critically dependent on intact central amygdala neurons in the rat. The behavioral data are, however, still compatible with a hypothesis of a temporary reduction in fear arousal during the initial phase of the passive avoidance conditioning.

Amygdala↗
PubMed1985

Comparison of electrolytic and ibotenic acid lesions in the lateral hypothalamus.

Electrolytic lesions in the lateral hypothalamus (LH) seriously affect ingestive behavior and sensorimotor functions in the rat. We here report that bilateral infusions of the neurotoxin, ibotenic acid (IBO) in the LH yield a decrease in body weight, but not to the same extent as electrolytic lesions. The sensorimotor impairments were most severe after electrolytic lesions. When tested in a residential maze on days 5-7 and 18-20 after surgery, both lesioned groups showed no lack of motivation to seek food and water. Histological examination of the LH following IBO exposure revealed extensive degeneration of neuronal cell bodies with little evidence of non-specific damage. Biochemical analysis of the rostral forebrain content of norepinephrine (NE) and serotonin (5-HT) revealed that the fibers passing through the LH remained largely intact in the IBO treated rats. The results suggest that the observed aphagia and adipsia is not due to a lack of motivation, but rather reflects changes in the process which operate to initiate eating and drinking. Furthermore, selective neuronal degeneration induced the same behavioral changes as the electrolytic ones, though not to the same extent.

Animals↗