Lucia Vitaioli

The hippocampus in spontaneously hypertensive rats : A quantitative microanatomical study

The influence of hypertension on the morphology of hippocampus was assessed in spontaneously hypertensive rats of two, four and six months and in age-matched normotensive Wistar-Kyoto rats. Values of systolic pressure were slightly increased in two-month-old spontaneously hypertensive rats in comparison with age-matched Wistar-Kyoto rats and augmented progressively with age in spontaneously hypertensive rats. No microanatomical changes were observed in the hippocampus of spontaneously hypertensive rats of two months in comparison with age-matched Wistar-Kyoto rats, whereas a decrease of white matter volume was observed in the CA(1) subfield and in the dentate gyrus of four-month-old spontaneously hypertensive rats. In the hippocampus of six-month-old spontaneously hypertensive rats a reduction of grey matter volume both in the CA(1) subfield and in the dentate gyrus, a loss of neurons affecting to a greater extent the CA(1) subfield and an increase of glial fibrillary acid protein-immunoreactive astrocytes was found. The occurrence of apoptosis and/or necrosis identified using the terminal deoxyribonucleotidyl transferase-mediated biotin-16-dUTP nick end labelling technique was also observed in the CA(1) subfield and to a lesser extent in the dentate gyrus. The only change noticeable in the CA(3) subfield of six-month-old spontaneously hypertensive rats was a slight increase in the number of glial fibrillary acid protein-immunoreactive astrocytes. These findings indicate the occurrence of neuronal loss and of astrocyte changes in the hippocampus of spontaneously hypertensive rats of six months, being the CA(1) subfield the area most affected. The relevance of these neurodegenerative changes in hypertension and the possible occurrence of apoptosis and/or necrosis as expression of hypertensive brain damage is discussed.

Effect of Calcium Antagonists on Glomerular Arterioles in Spontaneously Hypertensive Rats

Through the use of microanatomic techniques, we investigated the effects of treatment with some dihydropyridine-type calcium antagonists (CAs) (ie, lercanidipine, manidipine, and nicardipine) and with the nondihydropyridine-type vasodilator hydralazine on hypertension-dependent glomerular injury and on the morphology of afferent and efferent arterioles in spontaneously hypertensive rats (SHR). Fourteen-week-old male SHR and age-matched normotensive Wistar-Kyoto rats were left untreated (control groups). Four additional groups of 14-week-old SHR were treated for 12 weeks with daily oral doses of 2.5 mg/kg lercanidipine, 5 mg/kg manidipine, 3 mg/kg nicardipine, or 10 mg/kg hydralazine. These treatments decreased systolic blood pressure values to a similar extent in SHR. Signs of glomerular injury, as characterized by glomerulosclerosis, hypertrophy, and an increased number of mesangial cells, were observed in control SHR. The treatment with CAs improved glomerular morphology and decreased the number of mesangial cells. Lercanidipine and manidipine were more effective than nicardipine in countering glomerular injury. In the SHR, both afferent and efferent arterioles revealed luminal narrowing, accompanied by increased wall thickness in efferent arterioles. The dihydropyridine-type derivatives that were tested decreased the luminal narrowing of afferent arterioles. Lercanidipine and manidipine countered the luminal narrowing of efferent arterioles. Hydralazine had no effect on hypertension-dependent glomerular injury or vascular changes. The present data indicate that lercanidipine and manidipine vasodilate afferent and efferent arterioles in SHR. A vasodilatory activity on efferent arteriole, which is not induced by the majority of CAs, may represent an useful property in the treatment of hypertension complicated by renal disease.

Increased Expression of Glial Fibrillary Acidic Protein in the Brain of Spontaneously Hypertensive Rats

Astrogliosis, consisting in astroglial proliferation and increased expression of the specific cytoskeletal protein glial fibrillary acid protein (GFAP) is common in several situations of brain damage. Arterial hypertension, which induces cerebrovascular changes, can cause also brain damage, neurodegeneration and dementia (vascular dementia). This study was designed to assess astroglial reaction in different brain areas (frontal cortex, occipital cortex, hippocampus and striatum) of spontaneously hypertensive rats (SHR) in the pre‐hypertensive phase (2 months of age), in the developing phase of hypertension (4 months of age) and in established hypertension (6 months of age). SHR were compared to age‐matched normotensive Wistar‐Kyoto (WKY) rats. Analysis included reverse transcription‐polymerase chain reaction (RT‐PCR) of GFAP mRNA, GFAP immunochemistry (Western blot analysis) and immunohistochemistry. A significant increase of GFAP mRNA and an increase of GFAP immunoreactivity were noticeable in different brain areas of SHR compared to normotensive WKY rats at 6, but not at 2 or 4 months of age. Immunohistochemistry revealed a numerical augmentation (hyperplasia) and an increase in size (hypertrophy) of GFAP‐immunoreactive astrocytes in frontal cortex, occipital cortex and striatum of SHR. In the hippocampus of SHR only a numerical increase of GFAP‐immunoreactive astrocytes was found. These finding demonstrating the occurrence of astrogliosis in the brain of SHR with established hypertension suggest that hypertension induces a condition of brain suffering enough to increase biosynthesis and expression of GFAP similarly as reported in several neurodegenerative disorders and in brain ischemia.

Microanatomical changes of intracerebral arteries in spontaneously hypertensive rats : a model of cerebrovascular disease of the elderly

Changes occurring in intracerebral arteries of 24-week-old spontaneously hypertensive rats (SHR) compared with age-matched normotensive Wistar-Kyoto (WKY) rats were assessed using microanatomical techniques associated with image analysis. Morphometric parameters investigated included arterial diameter, lumen area, wall area, and wall-to-lumen ratio. Intracerebral arteries (lumen diameter>46 microm) and arterioles (lumen diameter 46-10 microm) of frontal cortex, striatum, and hippocampus were examined. In frontal cortex of SHR arterial wall hypertrophy and luminal narrowing were observed. In striatum, an increase of wall area not accompanied by luminal narrowing predominates resulting in arterial hypertrophy without vasoconstriction. In hippocampal arteries of SHR, luminal narrowing, without changes of wall area was found indicating the occurrence of remodeling. In brain areas investigated, hypertensive changes affected primarily arterioles. The demonstration of a sensitivity of intracerebral arteries to hypertension suggests that changes of these vessels may represent a cause of brain structural alterations occurring in hypertension. The specificity of alterations occurring in intracerebral arteries of brain areas investigated may account for the different localization of cerebral lesions in cerebrovascular disease. The possibility that microanatomical changes developed in intracerebral arteries of SHR may represent a model of cerebrovascular disease of the elderly is discussed.

The cerebral cortex of spontaneously hypertensive rats: a quantitative microanatomical study.

The morphology of cerebral cortex was investigated in male spontaneously hypertensive rats (SHR) aged 2, 4 and 6 months (pre‐hypertensive, developing hypertension and established hypertension respectively) and in age‐matched normotensive Wistar‐Kyoto (WKY) rats using quantitative microanatomical techniques. Analysis included frontal and occipital cortex as a paradigm of motor and sensory cerebrocortical areas respectively. Values of systolic pressure were slightly higher in 2‐month‐old SHR compared to age‐matched WKY rats and augmented progressively with increasing age in SHR. In frontal cortex of SHR a decrease of nerve cell number and of cortical volume was observed in layers V and VI of 4‐ and 6‐ month‐old SHR, and in layers I–IV of 6‐ month‐old SHR. In occipital cortex a decrease of the number of nerve cells and of cortical volume was observed in layers V and VI of 2‐, 4‐, 6‐ month‐old SHR, and in layers I–IV of 6‐month‐old SHR. Numerical decrease of neurons in SHR affected to a greater extent occipital cortex than frontal cortex. An increase in the number of glial fibrillary acidic protein (GFAP)‐immunoreactive astrocytes (hyperplasia) as well as in the mean immune reaction area (hypertrophy) was found in the two cerebrocortical areas investigated of 6‐month‐old SHR. The occurrence of apoptosis and/or necrosis identified using the terminal deoxyribo‐nucleotidyl transferase (TdT)‐mediated biotin‐16‐dUTP nick‐end labeling (TUNEL) technique was also observed in frontal and occipital cortex of 6‐month‐old SHR, but not of younger cohorts. These findings indicate the development of microanatomical changes in the cerebral cortex of SHR, the extent of which increases parallel with the progression of hypertension. The occurrence of cerebrocortical apoptosis and/or necrosis as well as the obvious astrogliosis occurring in established hypertension may account for the increased risk of vascular dementia that represents a specific trait of complicated hypertension.

Forebrain white matter in spontaneously hypertensive rats: a quantitative image analysis study.

The volume and the morphology of brain white matter as well as the number and the size of glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes were investigated in 6-month-old spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto (WKY) rats. The volume of frontal and occipital cortex and of hippocampus was decreased in SHR in comparison with normotensive rats, whereas the volume of neostriatum was unchanged. A remarkable decrease of the volume of internal capsule and striosomes, a moderate reduction of that of corpus callosum and no changes of the volume of external capsule and of white matter of hippocampus were also observed in SHR. In SHR the number of astrocytes was higher in the frontal and occipital cortex and in the white matter of the CA1 and CA3 subfields of the hippocampus, but not in the corpus callosum or in the grey matter of the CA1 and CA3 subfields. Staining for myelin did not reveal alterations in single fibre sheath morphology. These findings indicate the occurrence of changes of forebrain white matter in SHR, consisting in the reduction of it without qualitative modifications of myelinated fibres. The development of gliosis apparently not related with changes of volume of white matter was also found.

Morphological and conduction changes in the sciatic nerve of spontaneously hypertensive rats

The morphology and function of sciatic nerve were investigated in spontaneously hypertensive rats (SHR), either control or hydralazine-treated, and in normotensive Wistar Kyoto rats of 6 months of age. In control SHR decreased percentages of class I fibers (20-15 microm in diameter), of axonal NFP-H 200 kDa neurofilament protein immunoreactivity and of nerve conduction velocity were found. The percentages of class III (10-5 microm in diameter) and IV (<5 microm in diameter) and of S100beta-immunoreactive Schwann cell profiles were increased. Treatment with the hypotensive drug hydralazine countered sciatic nerve changes. The shift of nerve composition vs. smaller fibers is probably the cause of reduced nerve conduction velocity found in SHR and is consistent with the occurrence of a sympathetic hyper innervation in this animal model of hypertension. Our findings support the hypothesis that arterial hypertension may represent a risk factor of neuropathy.

Effects of dihydropyridine-type Ca2+ antagonists on the renal arterial tree in spontaneously hypertensive rats

The effects of hypertension and of treatment with dihydropyridine-type Ca 2+ antagonists and the vasocilator hydralazine on renal arterial tree were investigated in spontaneously hypertensive rats (SHR) with quantitative microanatomical techniques. Pharmacological treatment decreased to a similar extent systolic blood pressure values in SHR. Increased thickness of the tunica media of intrarenal arteries accompanied and luminal narrowing were observed in control SHR. Lercanidipine, manidipine, and nicardipine signficantly countered wall thickening and luminal narrowing. Hydralazine countered luminal narrowing only. Dihydropyridines exerted renal vasocilatory activity primarily on resistance arteries, being lercanidipine the only compound active on small sized arteries.

Ultrastructural Histochemical Study on Glycoconjugates of the Submandibular Gland of Rabbits

An ultrastructural histochemical study was carried out on submandibular glands of rabbits. Stainings were performed with dialysed iron (DI), high iron diamine (HID), tannic acid uranyl acetate (TA-U), tannic acid-ferric chloride (TA-F) sequence, and periodate-thiocarbohydrazide-silver proteinate (PA-TCH-SP) method. It was demonstrated that neutral glycoproteins are present in the cells with dark granules of the preterminal tracts, and that neutral and acid glycoproteins are present in the cells with light granules of the terminal tracts. Result are discussed and compared to other previously obtained histochemical and biochemical data.

Fluctuations in arylsulphatase activity in the rabbit endometrium during the sexual cycle

SummaryHistochemical and biochemical studies were performed to verify the presence of arylsulphatase A (ASA) and B (ASB) in the rabbit uterus. Fluctuations in the activity of these sulphatases during the sexual cycle were also studied. Some structural and functional properties of purified ASA were determined. The results indicate that arylsulphatases are active in the endometrium during both the estrogenic and progesteronic phases. The activity of ASA was much more intense than that of ASB; it increased during estrus and decreased during the post-ovulatory phase. ASB activity, however, decreased during estrus and increased during the post-ovulatory phase. The significance of these fluctuations is discussed in relation to the action of sexual hormones and physiological substrates of arylsulphatases.