Cognitive impairment and morphological changes in the dorsal hippocampus of very old female rats.

The hippocampus, a medial temporal lobe structure necessary for the formation of spatial memory, is particularly affected by both normal and pathologic aging. In previous studies, we observed a significant age-related increase in dopaminergic neuron loss in the hypothalamus and the substantia nigra of female rats, which becomes more conspicuous at extreme ages. Here, we extend our studies by assessing spatial memory in 4-6 month-old (young), 26-month-old (old) and 29-32-month-old (senile) Sprague-Dawley female rats as well as the age-related histopathological changes in their dorsal hippocampus. Age changes in spatial memory performance were assessed with a modified version of the Barnes maze test. We employed two probe trials (PTs), one and five days after training, respectively, in order to evaluate learning ability as well as short-term and longer-term spatial memory retention. A set of relevant hippocampal cell markers was also quantitated in the animals by means of an unbiased stereological approach. The results revealed that old rats perform better than senile rats in acquisition trials and young rats perform better than both aging groups. However, during short-term PT both aging groups showed a preserved spatial memory while in longer-term PT, spatial memory showed deterioration in both aged groups. Morphological analysis showed a marked decrease (94-97%) in doublecortin neuron number in the dentate gyrus in both aged groups and a reduction in glial fibrillary acidic protein-positive cell number in the stratum radiatum of aging rats. Astroglial process length and branching complexity decreased in aged rats. We conclude that while target-seeking activity and learning ability decrease in aged females, spatial memory only declines in the longer-term tests. The reduction in neuroblast number and astroglial arborescence complexity in the dorsal hippocampus are likely to play a role in the cognitive deficits of aging rats.

Cranial and cerebral-ventricular landmarks for accurate stereotaxic approach to hypothalamic nuclei in the goat brain.

This paper describes a new stereotaxic coordinate system for the goat brain based on cranial landmarks. An osseous triangle (a-b-c) formed by the point of junction of the crista galli with the caudal ventral part of the frontal sinus septum (a), the external occipital protuberance (b), and the midsagittal projection of the external acoustic meatus (c), was measured using lateral radiographs and ventriculographs and showed a constant mathematical relation. The rostral angle was 20.3 +/- 1.0 (mean +/- SD) degree in 23 goats studied regardless of their cranial size which varied considerably from one animal to another. The hypotenuse length (a-b distance) was found to be a good predictor of the rostral nuchal position of the anterior commissure (AC) and the infundibular recess of the third ventricle (INF), by which the individual variance of the stereotaxic coordinates for a given hypothalamic structure could be compensated. The anterior-posterior distances from the external acoustic meatus was highly correlated with the a-b distance for AC (r = 0.88) and INF (r = 0.90). Using these cranial landmarks and the method outlined in this paper, uncertainty in coordinate values for AC and INF in the goat brain was reduced considerably in comparison to deviation observed when the ordinary Horsley-Clarke axis (Reid's plane) was employed.

Hypothalamic structures of the goat on stereotaxic coordinates.

Serial brain sections of 50 microns thickness were made from celloidin embedded brains taken from adult male goats. They were stained by means of cresyl violet either with or without luxol fast blue, and the cellular and fiber patterns were examined both macro- and microscopically. Brain sections were transferred on to scanner and their images were recorded by computer. The brain maps were made with the aid of appropriate software and presented as a series of coronal graphics of the hypothalamus that cover the area from the mammillary tubercles to the level of the optic chiasm. The thalamus and the amygdala were also included. Reduction of the brain tissue during the histological procedure was analyzed by means of coronal and sagittal scanning by computer tomography (CT) imaging. It was related to the proportion of the gray and white matters in the encephalic area. The hypothalamus showed an 11% shrinkage. The stereotaxic location of the hypothalamic nuclei was estimated by compensating for the reduction rate of the area. The stereotaxic coordinates developed for goat brain were easy to apply and transfer to the computer coordinate system.

[Feline immunodeficiency virus infection: interferon gamma secretion in a T-lymphoblastoid infected cell line]. / Virus de la inmunodeficiencia felina: producción de interferón gamma en cultivos de linfocitos T infectados.

Feline immunodeficiency virus (FIV) was first isolated in 1987 from a cat with an acquired immunodeficiency syndrome (AIDS)-like disease. Since then, FIV has been subject of intensive research. Perturbation in cytokine production observed in human immunodeficiency virus infection (HIV) is paralleled in the FIV-infected cat. Interferon gamma (IFN-gamma) is a type 1 lymphokine that exert protective effects during infection through upregulation of cellular immunity and phagocytic functions. The present study was carried out to examine the expression of IFN-gamma in a feline T-lymphoid cell line (Fel-039) infected with FIV as well as the viral replication in these cells after addition of recombinant-type feline IFN (rIFn). We found a marked inhibition of IFN-gamma release in Fel-039 cells infected with FIV which might be pivotal for high viral replication. Infection of Fel-039 cells with FIV resulted in an increase of the reverse transcriptase (RT) activity in the culture supernatant. When the cells were cultured in the presence of rIFN a significant dose-dependent inhibition of RT activity of FIV was detected without cytotoxicity. On the basis of these in vitro results, we suggest that IFN therapies aimed at restoring depleted level of this important cytokine in FIV infected T-cells make this compound a promising candidate for development of suitable drugs for AIDS treatment.

Anatomical study of the forearm and hand nerves of the domestic cat ( Felis catus), puma ( Puma concolor) and jaguar ( Panthera onca).

The innervation of the forearm and hand regions of cats has not been well described despite its importance for any surgery or any neurological disorder. It is probably the main area where disorders of peripheral nerves in this species are observed. In felines, the forelimbs facilitate the jump and represent the most important way for capturing prey. The main muscles and nerves involved in this activity are located in the region of the forearm and hand. The aim of the present study was to provide a detailed description of the innervation of the forearm and hand regions of the jaguar and puma, in comparison with that of the domestic cat, contributing thus with the anatomical knowledge of the area for applying it to surgery and pathology. The forearms of three pumas and two jaguars (all of them fixed in formalin) and of six domestic cats (fresh) were dissected. The nerves path and their forearm distribution patterns of all three species were described. The analysed results indicate that the observed variations between species are minimal; thus, the anatomy described for domestic cats can be widely applied to American wild felids.

Dopaminergic mesencephalic systems and behavioral performance in very old rats.

Morphologic and functional studies describing the impact of aging on mesencephalic dopaminergic (DA) neurons in laboratory animals are rather scanty and inconclusive. In rats, stereological studies characterizing age changes in the mesencephalic DA neurons have not been documented. In order to fill this information gap and to determine whether the very old rat may serve as a suitable animal model of Parkinson's disease, we performed a stereological assessment of the mesencephalic tyrosine hydroxylase immunoreactive (TH-ir) neurons in young-adult (4-6 months), old (22-24 months) and senile (30-32 months) Sprague-Dawley female rats. Morphometric analysis of the TH-ir neurons of the substantia nigra (SN) and ventral tegmental area (VTA) was performed using an appropriate image analysis system. Age changes in motor performance were assessed measuring the endurance of rats to hang from a wire mesh pole or to remain on a ramp set at different angles to the floor. Age changes in locomotion and exploratory activity were evaluated by the open field test. We observed a significant age-related reduction in TH-ir neuron numbers in the SN (17 and 33% reduction in old and senile rats, respectively compared with young counterparts) but not in the VTA. The size of the TH-ir cells increased significantly in both the SN and VTA of the senescent animals but TH labeling intensity fell. Motor, locomotor and exploratory performance deteriorated markedly in the old and senile rats as compared with young animals. These findings reveal the existence of a moderate but significant vulnerability of mesencephalic DA neurons to aging in rats. This phenomenon, which is particularly marked in the SN of very old rats, may contribute to the age-related decline in motor and exploratory performance recorded in this species.

Distribution of tyrosine hydroxylase-immunoreactive neurones in the diencephalon and mesencephalon of the coypu (Myocastor coypus).

The aim of the present study was to examine the catecholaminergic neurones located within the midbrain of the coypu, a South American hystricomorph rodent. The neuronal distribution of the catecholaminergic systems and morphological parameters of the immunostained cell bodies and fibres were investigated, using an immunohistochemical method. The brains of five coypu were fixed, immersed in gelatine-glycerol and cut in 40-micron slices using a freezing microtome. Samples were processed with ultrasound-based antigen retrieval and stained with labelled antityrosine hydroxylase monoclonal antibody. An image analyser was used to measure the neuronal bodies. The catecholaminergic neurones of the tuberoinfundibular system were mainly observed in the arcuate and periventricular nuclei with their axons projecting towards to the median eminence; they represented 28% of the global population of tyrosine hydroxylase-immunoreactive cells observed. Significant morphological differences were observed in comparison with the other two studied systems. Fifty per cent of total catecholaminergic neurones were detected in the nigrostriatal system distributed in the reticular and compact substance nigra. Most neuronal bodies had a fusiform aspect. The immunoreactive neurones of the mesolimbic system represented 22% of the total population. They were distributed around the interpeduncular nucleus. Two types of morphologically different catecholaminergic systems of the brain were established: hypothalamic neurones located in the periventricular and arcuate nuclei and mesencephalic neurones located in the substance nigra and interpeduncular nuclei. These systems showed morphological and probably physiological-pharmacological differences.

Virus de la inmunodeficiencia felina: producción de interferón gamma en cultivos de linfocitos T infectados / Feline immunodeficiency virus infection: interferon gamma secretion in a T-lymphoblastoid infected cell line

Feline immunodeficiency virus (FIV) was first isolated in 1987 from a cat with an acquired immunodeficiency syndrome (AIDS)-like disease. Since then, FIV has been subject of intensive research. Perturbation in cytokine production observed in human immunodeficiency virus infection (HIV) is paralleled in the FIV-infected cat. Interferon gamma (IFN-gamma) is a type 1 lymphokine that exert protective effects during infection through upregulation of cellular immunity and phagocytic functions. The present study was carried out to examine the expression of IFN-gamma in a feline T-lymphoid cell line (Fel-039) infected with FIV as well as the viral replication in these cells after addition of recombinant-type feline IFN (rIFn). We found a marked inhibition of IFN-gamma release in Fel-039 cells infected with FIV which might be pivotal for high viral replication. Infection of Fel-039 cells with FIV resulted in an increase of the reverse transcriptase (RT) activity in the culture supernatant. When the cells were cultured in the presence of rIFN a significant dose-dependent inhibition of RT activity of FIV was detected without cytotoxicity. On the basis of these in vitro results, we suggest that IFN therapies aimed at restoring depleted level of this important cytokine in FIV infected T-cells make this compound a promising candidate for development of suitable drugs for AIDS treatment.