José María Peinado

LIGHT MICROSCOPIC QUANTIFICATION OF MORPHOLOGICAL CHANGES DURING AGING IN NEURONS AND GLIA OF THE RAT PARIETAL CORTEX

Different changes in neuronal and glial population of the aging brain have been described; however, the degree and extent of these changes are controversial. This study evaluates the quantitative and cytomorphometric effects of aging on neuronal and glial populations in the parietal cortex of the rat.

QUANTITATIVE AND ULTRASTRUCTURAL CHANGES IN GLIA AND PERICYTES IN THE PARIETAL CORTEX OF THE AGING RAT

The frequency of astrocytes, microglia plus oligodendrocytes, and pericytes displaying nuclei was analyzed and quantified in 160‐μm‐wide strips of the parietal cortex (Par1 region) from young and aged Wistar rats. The study was performed on two groups of rats aged 3–4 and 32–36 months. Quantifications of the glial cell types and pericytes were made in 1‐μm‐thick sections stained with toluidine blue. Ultrathin sections were also made to analyze the ultrastructural features of these cells during aging. Astrocytes and pericytes increased in number by about 20% and 22%, respectively, with age. These increases were most significant in layers II–IV and V for both cellular types. Clusters of astrocytes were common in these layers of aging rats. The ultrastructural analysis also indicated changes in all cell types that stored inclusions and vacuoles with age, which were particularly abundant in microglial cells. End‐feet astrocytes and pericytes surrounding the vascular wall also contained vacuoles and inclusions, and consequently the vascular wall increased in thickness. In conclusion, the aging process increased astrocyte and pericyte populations, but not microglia plus oligodendrocyte populations, in the rat parietal cortex. Although no significant change in nuclear size could be observed in any cell type, all glial cells as well as pericytes underwent morphological ultrastructural changes. These modifications may result from the need to correct possible homeostatic imbalances during aging. Microsc. Res. Tech. 43:34–42, 1998.

Glutamic Acid as a Putative Transmitter of the Interhemispheric Corticocortical Connections in the Rat

Abstract The effect of hemidecortication on the endogenous levels of amino acids in medial, sulcal, and dorsal frontal cortex as well as in parietal, temporal, and occipital cortex of the rat was investigated. Under aseptic conditions, the right cerebral cortex was aspirated by suction. Then, 21 days later, the content of glutamic acid, aspartic acid, γ‐aminobutyric acid, glycine, serine, threonine, and alanine was analyzed in six areas of the intact contralateral cortex using GLC. The results demonstrated a specific decrease in the endogenous levels of glutamic acid in both parietal and temporal cortex after hemidecortication of the contralateral side. This finding suggests that glutamic acid may serve as a neurotransmitter for some of the interhemispheric corticoparietal and corticotemporal fibers. In a follow‐up experiment, the effect of a frontal lesion on the endogenous levels of the same amino acids in the striatum was also examined. In this case, the glutamic acid content exhibited a decrease of 31 % relative to the control value. This observation confirms the earlier finding of a glutamate‐containing pathway from the frontal cortex to the striatum.

Acute and chronic stress increase salivary cortisol: a study in the real-life setting of a national examination undertaken by medical graduates

Abstract Spanish medical graduates who apply for a medical specialty training position (MIR) must take an examination that will shape their future personal and professional lives. Preparation for the test represents an important stressor that persists for several months. The aim of this study was to elucidate the stress pattern of this group and evaluate possible changes in the circadian rhythm of cortisol release in medical graduates preparing for this test. A repeated-measures longitudinal study was performed, measuring the salivary cortisol concentrations in 36 medical graduates (13 males and 23 females; mean age of 24.2 years) on five sampling days. Five cortisol samples were collected from 07:00 to 21:00 h in order to monitor changes in the circadian rhythm. On all sampling days (except on the day of the official examination), anxiety and psychological stress were evaluated with the Spanish versions of the State-Trait Anxiety Inventory (STAI) and the Perceived Stress Scale (PSS). During the study period, participants showed higher levels of anxiety than the Spanish reference population as well as a progressive increase in self-perceived stress. A significant increase in salivary cortisol concentration was observed in both chronic (study and examination preparation) and acute (examinations) situations. Our results suggest that the cortisol awakening response (CAR) may be a good indicator of anticipatory stress but is unaffected by long-term examination preparation. Comparison of results between the official examination day and the mock examination days yielded evidence that learning may modulate the behavior of the hypothalamic–pituitary–adrenal axis.

Decrease in cytosolic Aspartyl-aminopeptidase but not in Alanyl-aminopeptidase activity in the frontal cortex of the aged rat

To test the neurotoxic hypothesis of excitatory amino acids, we evaluated the possible contribution to the free acidic amino acid pool of Aspartyl-aminopeptidase activity in the frontal cortex of adult (3 month old) and aged rats (3 groups of animals aged 26, 29 and 33 months). Aspartyl-aminopeptidase activity showed a significant decrease in the oldest rats (29 and 33 months old) whereas the activity of Alanyl-aminopeptidase, an unspecific enzyme, did not change with age. These data invalidate the idea that excess free acidic amino acids are released by aminopeptidases in the aged rat but do provide evidence of age-related changes in this enzymatic activity. The possible implications of our findings for general alterations in protein degradation are discussed.

Cerebral cortex and amino acid neurotransmitters: Higher levels of aspartic acid but not GABA in the frontal cortex of the rat

Endogenous levels of Aspartic acid, GABA and Glutamic acid plus Glutamine were measured in the frontal, occipital, temporal and parietal cortex. Aspartic acid levels were found higher in the frontal cortex than in the rest of the cortical areas studied. GABA, however, had a homogenous distribution among all cortical areas.

Effects of Contralateral Lesions and Aging on the Neuronal and Glial Population of the Cerebral Cortex of the Rat

Glial cells and pericytes are strongly involved in the neurodegenerative processes of the central nervous system. In the present study, we analyzed the cytomorphological effects as well as the reactive changes of glial cells and pericytes of two different neurodegenerative processes: normal aging and changes induced by contralateral implantation of a microdialysis probe. Quantifications were made in the frontal and parietal cortex of the rat. The results show that the microdialysis induced lesions affected all contralateral cortical layers, the microglia being the most proliferating type of cells. The aging process mainly affected the layer V where density of astrocytes was increased. Pericytes in frontal cortex did not show significant changes under our experimental conditions. We detected a significant increase in the number of these cells only in the parietal cortex of aging rats. In addition, pericytes and perivascular microglial cells accumulated a great number of dense and foamy inclusions during aging. Finally, both neurodegenerative processes, lesion and aging, seems to produce glial hyperplasia and hypertrophia through a different mechanism which also differentially affects the neuronal sprouting response.

Evoked GABA Release Is Not Mediated by N-Type VDCC in the Frontal Cortex of Awake Rats: Effects of Neomycin

The purpose of the present study was to analyze the Ca2+ channel involved in GABA release under resting and K(+)-evoked conditions in vivo. We used microdialysis to investigate the effects of the voltage-dependent calcium channel (VDCC) blockers neomycin, kanamycin, and omega-conotoxin GVIA, and the voltage-dependent Na+ channel blocker tetrodotoxin, in the frontal cortex of awake rats. The GABA content in frontal dialysates was analyzed by high performance liquid chromatography coupled to fluorescence detection. Basal GABA release was kanamycin, omega-conotoxin, and tetrodotoxin resistant, whereas neomycin induced a significant increase from the basal level. The K(+)-evoked release of GABA was kanamycin and omega-conotoxin resistant, but tetrodotoxin sensitive. The effects of neomycin were masked by the action of this drug on basal release. These results suggest that neomycin may affect GABA release in the frontal cortex through a mechanism independent of VDCC. In addition, the K(+)-evoked release of GABA in this cortical area was not mediated by the N-type voltage-dependent calcium channels, but was dependent on neural activity or TTX sensitive.

Putative amino acid neurotransmitters and the nucleus dorsomedialis thalamus-prefrontal cortex pathway in the rat

Endogenous levels of putative amino acid neurotransmitters (glycine, glutamic acid, aspartic acid, and GABA) in medial and sulcal prefrontal cortex of the rat were analyzed using gas liquid chromatography. No changes were found in the levels of these amino acids in medial and sulcal prefrontal cortex after lesion of the nucleus dorsomedialis of the thalamus suggesting, therefore, that the NDMT-prefrontal cortex pathway is not mediated by these amino acids.

Calidad de vida relacionada con la salud en una muestra de médicos internos residentes que realizan guardias en un Servicio de Urgencias: una perspectiva de género

BACKGROUND The high emotional burden of physicians working in emergency departments may affect their quality of life perception. AIM To evaluate health related quality of life among resident physicians performing shifts at an emergency department. MATERIAL AND METHODS Seventy one physicians aged 26,3 ± 1,7 years (47 women), working as residents in an emergency department, answered the short version of the Short-Form Health Survey Questionnaire (SF-36®). This questionnaire analyses eight domains: physical function, body pain, general health, vitality, social function, emotional role and mental health. RESULTS Women had a significantly worse perception than a reference population in four dimensions of the SF-36, especially mental health and social functioning. Men had scores similar to the reference population. Among women, vitality is the best predictor of mental health and social functioning. CONCLUSIONS Women working as residents in an emergency department have a worse perception of their quality of life than men performing the same job.Background: The high emotional burden of physicians working in emergency departments may affect their quality of life perception Aim: To evaluate health related quality of life among resident physicians performing shifts at an emergency department. Material and methods: Seventy one physicians aged 26 ± 2 years (47 women), working as residents in an emergency department, answered the short version of the SF-36 survey. This questionnaire analyses eight domains: physical function, body pain, general health, vitality, social function, emotional role and mental health. Results: Women had a significantly worse perception than a reference population in four dimensions of the SF-36, especially mental health and social functioning. Men had scores similar to the reference population. Among women, vitality is the best predictor of mental health and social functioning. Conclusions: Women working as residents in an emergency department have a worse perception of their quality of life than men performing the same job.