Expression of certain proteins in the subfornical organ and cerebrospinal fluid of spontaneously hypertensive rats

The objective of this study was to analyze the proteins in the cerebrospinal fluid of spontaneously hypertensive rats and to study their possible role in the relationship between hydrocephalus, arterial hypertension and variations in the subfornical organ. Brains and cerebrospinal fluid from control Wistar-Kyoto rats and spontaneously hypertensive rats sacrificed with chloral hydrate were used. Cerebrospinal fluid and extract of subfornical organ were processed by protein electrophoresis. Antisera against protein bands of 141, 117 and 48 kDa and Concanavalin A were used for immunohistochemical and western blot study of the subfornical organ, adjacent circumventricular structures and cerebrospinal fluid. Ventricular dilation in the spontaneously hypertensive rats and the presence of quite a lot of protein bands in the cerebrospinal fluid of the hypertensive rats, which were either not observed or scarcely present in the cerebrospinal fluid of the Wistar-Kyoto rats, were confirmed. The subfornical organ, third ventricle ependyma and choroideus plexus showed immunoreactive material for antibodies against 141kDa, 117 and 48 kDa proteins band (anti-B1, anti-B2 and anti-B3). The larger amount of the immunoreactive material was found in the subfornical organ of the spontaneously hypertensive rat. Our results and the alterations observed by other authors in the subfornical organ in hydrocephalic and hypertensive rats support the possibility that this circumventricular organ, some proteins of the cerebrospinal fluid and ventricular dilation could be connected with the physiopathology of this type of hypertension.

Alterations of the cerebrospinal fluid proteins and subcommissural organ secretion in the arterial hypertension and ventricular dilatation. A study in SHR rats

The aim of this work was to analyze the proteins in the cerebrospinal fluid (CSF) of spontaneously hypertensive rats, to study their possible role in the relationship between hydrocephalus, arterial hypertension and alterations in the subcommissural organ. Brains from control Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) sacrificed with chloral hydrate were used. Antiserums against some cerebrospinal fluid protein bands and Reissner's fiber (RF) were used for immunohistochemical study of the SCO. Ventricular dilation was observed in the lateral and third ventricle of the SHR. Third ventricle ependyma showed immunoreactive material (IRM) for antibody against 141 kDa protein band anti-B1 and 117 protein band anti-B2 and the SCO of the SHR showed a decrease of the IRM when compared with WKY rats. An alteration in the expression of anti-RF was found to compare the SCO of the WKY and SHR groups. Our results demonstrate that hydrocephalus and hypertension are interconnected in this kind of rat which produce alterations in SCO secretions and some proteins of the CSF.

Postnatal Development of the Secretory Activity of the Goat Subcommissural Organ. A Reissner's Fibre and Angiotensin II Immunohistochemical Study

Subcommissural organ (SCO) secretory activity of the goat (variations of Capra hircus, that live in arid conditions) was examined during the postnatal development, using specific antibodies against the Reissner's fibre (AFRU) and angiotensin II (AAGII). The SCO was strongly stained with the anti-glycoproteins that form the Reissner's fibre and lightly marked with the anti-angiotensin II. The AFRU-immunoreactivity (ir) was found in the ependymal and hypendymal cells and in the ventricular and peripheral secretory routes of the goat SCO. The amount AFRU increases at 6 months and decreases at adult age. In contrast, the anti-angiotensin II-ir was mainly found in the adult age, not being practically observed at one postnatal month. The AAGII-ir was mainly found in ependymal cells in which AFRU-ir was downregulated. In addition, we detected the presence of double immunostained for AFRU and AAGII in ependymocytes of the pre-commissural and subcommissural parts. In conclusion the present results may suggest a functional interrelation between AAGII and the secretory activity of the SCO of this kind of goat.

Effect of hypertension on the angiotensin II fibres arriving at the posterior lobe of the hypophysis of the rat. An immunohistochemical study

We studied immunohistochemically the posterior lobe of the hypophysis (PL) of 15-week-old spontaneously hypertensive rats (SHR) and of matched normotensive Wistar Kyoto rats (WKY), by using our own polyclonal antibody raised in mice against Angiotensin II (mouse-antiangiotensin II, MAAII). The blood pressure, water intake and volume of the PL were also recorded. The SHR rats were hypertensive, drank more water and showed a clear hypertrophy of their hypophysial PL. Also the PL of the SHR animals showed an increase in the immunoreactivity to the anti-angiotensin II antibody in the fibres arriving at the PL, with respect to the PL of WKY rats. This increase is compatible with the hyperactivity of the brain RAS, depletion of vasopressin content in the PL and increase in plasmatic levels of vasopressin described in SHR rats with respect to normotensive animals, as angiotensin II could locally stimulate vasopressin release to plasma from the neurohypophysis.

Effect of hypertension and captopril treatment on the vasopressin in the rat median eminence and posterior lobe of the hypophysis. An immunohistochemical study

The present study analyses the effects of hypertension and/or its oral treatment with captopril (angiotensine-converting enzyme inhibitor) on the rat median eminence (ME) and the posterior lobe of the hypophysis (PL). After an immunohistochemical reaction using an antibody against arginine-vasopressin, we compared by densitometry the amount of vasopressin immunoreactive material (vasopressin-ir) of these centers in 4 groups of animals: control Wistar Kyoto rats (WKY), spontaneously hypertensive rats (SHR), WKY rats treated with captopril (WKY-T) and SHR rats also treated with the same drug (SHR-T). Captopril was administrated at a dosage of 0.1 mg/ml in the drinking water from the 8th to the 15th weeks. We have found that the rats showing the lowest level of vasopressin-ir, in both ME and PL, were those from the SHR group, the concentration increasing after oral captopril treatment (SHR-T), although without reaching the values of WKY rats. Then, ACE inhibition by captopril influences vasopressin content in brain areas where the hormone is concentrated before being released, which supports the hypothesis that suggests a central modulatory effect of ACE inhibitors, contributing to their therapeutic action on hypertension.

Effects of alcohol and aging on the cingular (area 24) and frontal (area 6) cortical areas of the mouse

We have studied the morphometric changes of the neurons of the cingular area 24 and frontal area 6 of the mouse, produced by age and/or chronic alcohol intake. The parameters analyzed were nuclear area of these cortical neurons and cellular density (cell/neuropil coefficient). We detected a decrease in the number of neurons with age in practically all layers of the control animals. In the animals that chronically ingested the alcoholic solution, we also detected a decrease in the number of neurons with age, but only in layer V of the frontal cortex and in layer VI of the cingular area 24. The comparison between the control and the alcoholic group showed that alcohol intake caused an increase in the nuclear area of the neurons in layer II-III of the frontal cortex at 180 days, while in the cingular cortex the increase in nuclear area of its neurons was significative at 180 days in layer II-III and at 35 and 180 days in layers V and VI. We think that these changes are the expression of the neuronal plasticity in both cortical areas in response to the alcohol exposure.

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.

The effects of chronic administration of captopril on the mouse median eminence

The effects of Captopril (an angiotensin-converting enzyme inhibitor) on the median eminence (ME) of the male albino mouse have been examined using morphometric and immunohistochemical procedures. We measured the nuclear area of the ependymocytes of the ME and of the glial cells of the reticular external zone of the ME. We also determined the cell/neuropil coefficient (CNC), which expresses the relation between cellular area and neuropil of the ME, and the global volume of the ME in each animal. For the immunohistochemical study we used rabbit antiarginine-vasopressin, and compared the results in the different groups of mice. We detected an increased in the immunoreactive material (arginine-vasopressin, A-V) and an increase in the global volume of the organ and also an increase of the neuropil of the ME after the longest exposure to the drug. These alterations could be related to the inhibition of the brain angiotensin II by captopril and the accumulation of vasopressin in the fibrous tract that runs from the paraventricular nucleus (PVN) to the neurohypophysis.

Sources of GABAergic input to the inferior colliculus of the rat

We have studied the GABAergic projections to the inferior colliculus (IC) of the rat by combining the retrograde transport of horseradish peroxidase (HRP) and immunohistochemistry for gamma-amino butyric acid (GABA). Medium-sized (0.06-0.14 microliter) HRP injections were made in the ventral part of the central nucleus (CNIC), in the dorsal part of the CNIC, in the dorsal cortex (DCIC), and in the external cortex (ECIC) of the IC. Single HRP-labeled and double (HRP-GABA)-labeled neurons were systematically counted in all brainstem auditory nuclei. Our results revealed that the IC receives GABAergic afferent connections from ipsi- and contralateral brainstem auditory nuclei. Most of the contralateral GABAergic input originates in the IC and the dorsal nucleus of the lateral lemniscus (DNLL). The dorsal region of the IC (DCIC and dorsal part of the CNIC) receives connections mostly from its homonimous contralateral region, and the ventral region from the contralateral DNLL. The commissural GABAergic projections originate in a morphologically heterogeneous neuronal population that includes small to medium-sized round and fusiform neurons as well as large and giant neurons. Quantitatively, the ipsilateral ventral nucleus of the lateral lemniscus is the most important source of GABAergic input to the CNIC. In the superior olivary complex, a smaller number of neurons, which lie mainly in the periolivary nuclei, display double labeling. In the contralateral cochlear nuclei, only a few of the retrogradely labeled neurons were GABA immunoreactive. These findings give us more information about the role of GABA in the auditory system, indicating that inhibitory inputs from different ipsi- and contralateral, mono- and binaural auditory brainstem centers converge in the IC.

Postnatal development of NADPH-diaphorase activity in the superior colliculus and the ventral lateral geniculate nucleus of the rat

We have studied the postnatal development of dihydronicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) activity in the superior colliculus (SC) and the ventral lateral geniculate nucleus (LGv) of the rat. We describe two different developmental patterns of NADPH-diaphorase activity. The first pattern, observed in the deep layers of the SC, shows a transient activity during the first week which progressively decreases during the following two weeks. The second pattern is observed in the superficial layers of the SC and in the LGv. They become positive during the first week, their NADPH-d activity increases progressively during the second and third weeks, reaching the adult pattern at the fourth week. On the whole, the developmental chronology of the laminar distribution of NADPH-d in the SC displays an inside-out pattern. Our results suggest that NADPH-d activity may play different roles at different stages of the developing nervous system.

Effects of postnatal administration of ethanol on the M. gastrocnemius of the albino mouse

A combined morphometric-histochemical (mATPase) study of the effects of ethanol during postnatal development on the m. gastrocnemius has been performed in the albino mouse. The experimental group received ethanol in the drinking water until sacrifice at the age of 40 days. Based on the fiber composition, three different areas are distinguished in the m. gastrocnemius of the mouse. The typical location of these areas does not change after ethanol administration. However, postnatal administration of ethanol produces a selective atrophy and a decrease of the number of type IIb (fast glycolytic) fibers. Concurrently, the number of type IIa (fast oxidative-glycolytic) fibers increases.