María Del Mar Pérez-Delgado

Expression of dopamine and vesicular monoamine transporters and differential vulnerability of mesostriatal dopaminergic neurons.

Numerous studies suggest that the dopamine transporter (DAT), responsible for dopamine reuptake, may act as a vulnerability factor in the pathogenesis of Parkinsons disease (PD) and the vesicular monoamine transporter (VMAT2), responsible for its vesicular storage, as a neuroprotective factor. However, the relevance of each on the differential vulnerability of midbrain DA cells remains uknown. Here we studied the relationship between the expression pattern (mRNA and protein) of both transporters and the differential vulnerability of midbrain DA cells in a model of PD (intracerebroventricular injection of 6‐OHDA in rats) and in monkey and human midbrain. Our results revealed that the expression patterns for VMAT2 mRNA and protein and DAT mRNA are similar, with the highest levels in the rostromedial region of substantia nigra (SNrm), followed by the caudoventral region of SN (SNcv), the ventral tegmental area and pigmented parabrabraquial nucleus (VTA/PBP), and finally the linear and interfascicular nuclei (Li/IF). In contrast, the expression of DAT protein in rats, monkeys, and humans followed a caudoventrolateral‐to‐rostrodorsomedial decreasing gradient (SNcv > SNrm > VTA/PBP > Li/IF), matching the degeneration profile observed after intracerebroventricular injection of 6‐OHDA and in PD. In addition, DAT blockade made all midbrain DA cells equally resistant to 6‐OHDA. These data indicate that DAT protein levels, but not DAT mRNA levels, are closely related to the differential vulnerability of midbrain DA cells and that this relationship is unaffected by the relative levels of VMAT2. Furthermore, the difference between DAT mRNA and protein profiles suggests internuclear differences in its posttransductional regulation. J. Comp. Neurol. 479:198–215, 2004.

Brainstem projections to the medial preoptic region containing the luteinizing hormone-releasing hormone perikarya in the rat. An immunohistochemical and retrograde transport study

The afferent projections to the anterior medial preoptic area (MPA) from the brainstem have been studied, in female Wistar rats, by retrograde tracing with horseradish peroxidase (HRP). The HRP was injected by iontophoresis into the preoptic region containing the luteinizing hormone-releasing hormone (LHRH) perikarya. The brain sections including the MPA were reacted with diaminobenzidine (DAB) to reveal the injection site; the LHRH cells were then immunohistochemically identified using DAB with ammonium nickel sulphate. When the injection site incorporated the LHRH cells, the brainstem sections were reacted with the DAB nickel solution to detect lysosomal HRP and then immunohistochemically processed to locate the adrenaline-synthesizing cells using DAB alone. The results confirm the brainstem projections to the MPA from the central grey matter, ventral tegmental area, subcoeruleus area, the dorsal raphe nucleus, the lateral parabrachial nucleus, the raphe pontis nucleus, the raphe obscurus nucleus, the region of the paragigantocellular nucleus and the nucleus of the solitary tract. Given the considerable evidence implicating the ascending adrenergic systems in the regulation of LHRH, we focused our attention on the afferents from the locus coeruleus, area postrema and the adrenaline-synthesizing cell groups (C1-3). The only cells which were retrogradely labelled and immunopositive for phenylethanolamine N-methyltransferase were found in C3.

Interleukin-6 and Nitric Oxide Synthase Expression in the Vasopressin and Corticotrophin-releasing Factor Systems of the Rat Hypothalamus

Nitric oxide synthase (NOS) and interleukin-6 (IL-6) are constitutively expressed in hypothalamic cells. However, phenotypic and functional aspects of these cells remain unknown. We have studied the expression pattern of these two molecules in hypothalamic cells expressing corticotropin-releasing factor (CRF) and arginin-vasopressin (AVP), two major regulatory peptides in the hypothalamus-pituitary system, using immunofluorescence, intracerebroventricular injection of colchicine, and the study in parallel of the labeling pattern of axons in the median eminence. Within AVP cells, we distinguished two different populations: large, intensely stained AVP cells coexpressing IL-6; and large, intensely stained AVP cells coexpressing IL-6 and NOS. Within the CRF cells, we distinguished three different populations: large, intensely stained CRF cells immunonegative for AVP, NOS, and IL-6; large cells weakly stained for CRF and AVP, immunopositive for NOS and immunonegative for IL-6; and small cells intensely stained for CRF and AVP and immunonegative for IL-6 and NOS. In addition, we also found AVP cells containing IL-6 in the suprachiasmatic nucleus. These results suggest that neuronal NOS and IL-6 may be involved in different modulatory processes in hypophysiotropic and non-hypophysiotropic cells.

Changes in the secretory activity of the subcommissural organ of spontaneously hypertensive rats

The subcommissural organ (SCO) is a glandular circumventricular organ secreting glycoproteins into the cerebrospinal fluid. The SCO of 15-week-old spontaneously hypertensive rats (SHR) and of matched normotensive Wistar-Kyoto rats (WKY) was studied immunocytochemically by using an antibody against the glycoproteins secreted by the SCO. The blood pressure, water intake and volume of brain ventricles of SHR and WKY rats were also recorded. The SHR were hypertensive, drank more water and did not display dilatation of the brain ventricles. The SCO of the SHR rats showed a drastic decrease of the immunoreactive material stored in the rough endoplasmic reticulum whereas the amount of immunoreactive apical secretory granules did not vary with respect to the SCO of WKY rats. These changes are compatible with an increased secretory activity of the SCO of the SHR rats. It is suggested that the changes in the SCO of SHR rats, and their hypertensive state, are interrelated phenomena.

Effects of chronic alcohol intake on the vasopressin content in the hypothalamic paraventricular and supraoptic nuclei of the mouse. An immunohistochemical and morphometric study

The present study analyses the response of the paraventricular (PVN) and supraoptic (SPO) nuclei of the hypothalamus of the male mouse to chronic alcohol intake by immunohistochemical and morphometric methods. We relate the intensity of the reaction to A-V with the vasopressin content of the nucleus, as all the slides, from the control and experimental groups, were processed at the same time and with the same solutions of the antibodies. We suggest that the accumulation of vasopressin, observed in the alcohol-treated animals, of both hypothalamic nuclei could be related to an inhibition of vasopressin release and/or transport from the SPO and PVN to the neurohypophysis and to an increase in vasopressin synthesis in the SPO as this nucleus shows an increase in its nuclear sizes, an index of the function of the neurons.

Alcohol Intake Effects on the Dorsal Vagal Complex of the Rat: A Cellular Morphometric Study

We have analyzed the morphometric effects on the dorsal vagal complex (DVC) of the rat of alcohol exposure and/or hypoproteic diet intake during 8 weeks. In the area postrema (AP), alcohol treatment (combined with normal isoproteic or hypoproteic diet) caused a significant decrease in karyometric parameters. In the dorsal motor nucleus of the vagus (DMV) and nucleus tractus solitari (NTS), the alcohol isoproteic intake (AI) produced an increase in neuron size (expressed by an increase in the neuronal nuclear area and the cell/neuropil coefficient). The hypoproteic diets produced a reduction in the global volume of each structure of the DVC which was accompanied by a decrease in global brain volume. These results indicate that after 8 weeks of treatment, alcohol is the main cause of the morphometric alteration found in the DVC, while variations in the amount of protein intake appear to produce global effects on the whole brain.

EFFECT OF ETHANOL ON LIVER CELL - DEVELOPMENT IN THE MALE ALBINO MOUSE

The aim of this study is to determine the influence of ethanol on the development of periportal and pericentral hepatocytes and their nuclei, comparing it with the development of these cells and nuclei in a control, age-matched population. In male albino mice fed with 20% ethanol added to drinking water and sacrificed at day 25, 35, 85 and 180 of life haematoxylin-eosin stained liver specimens were studied with the aid of a LEITZ ASM semiautomatic autoanalyzer. The nuclear area of at least 25 hepatocytes with evident nucleoli was measured at each of 3 periportal and 3 pericentral fields. The area of the cells of the same fields was estimated by dividing the area of the fields by the number of hepatocyte nuclei present in them. Both cellular and nuclear areas of periportal and pericentral hepatocytes of the 25-day-old animals were smaller than those of age-matched controls. By contrast, the experimental group showed a striking increase both in cellular and nuclear size in the pericentral hepatocytes, but not in the periportal ones. Thus, ethanol seems to inhibit the initial growth of cells and nuclei; but, after maturation, it causes a marked increase not only in cellular size of pericentral hepatocytes, especially in 180-day-old animals, but also in nuclear size, already evident in the 35-day-old mice.

Vitamin D (soltriol) target cells in the Harderian gland of the Siberian hamster (Phodopus sungorus)

Harderian glands of female and male Siberian hamsters (Phodopus sungorus) were studied after a subcutaneous injection of 3H-dihydroxycholecalciferol (vitamin D, soltriol). Autoradiograms revealed the presence of nuclear concentration of the hormone in certain alveolar cells and in myoepithelial cells. The proportion of labeled cells varied between 5.5 and 19% of the total cell number, with an average of 9.5% in female and 12.4% in male hamsters. The data suggest that the functions of the Harderian gland could undergo seasonal changes under the control of vitamin D.

Karyometric development of four topographic subdivisions of the paraventricular nucleus in normal and castrated mice

Abstract A karyometric study of the spontaneous development of four topographic subdivisions in the paraventricular nucleus was made in male albino mice from the 5th to the 190th day of postnatal life. Anoter 25 animals were castrated at 20 days and examined at 25, 35, 45, 55 and 85 days of life. A comparison was established between both groups of mice.

The effects of chronic administration of captopril on the mouse subfornical organ and area postrema

We have studied by morphometric procedures the chronic effect of captopril on the subfornical organ (SFO) and area postrema (AP) of the adult mouse. Oral administration of captopril does not produce any change in the size of individual nuclei of the ependymocytes and neurons in both centers. However, there are other quantitative effects of captopril on the global volume of the SFO and on the neuropil and vascular elements of both the SFO and AP which present a significant increase. It is suggested that this increase is due to metabolic processes at the level of both circumventricular organs.