Age-dependent changes in the expression of dopamine receptor subtypes in human peripheral blood lymphocytes

The pharmacological profile and the density of dopamine D3 and D5 receptor subtypes expressed by human peripheral blood lymphocytes of subjects of different ages (ranging from 20 to 75 years) were assessed using radioligand binding techniques. Dopamine D3 receptor was assayed with [3H]7-hydroxy-N,N-di-n-propyl-2-aminotetraline ([3H]7-OH-DPAT) as a ligand. Dopamine D5 receptor was assayed using [3HIR]-(+)-(-chloro-2,3,4,5, tetrahydro-5-phenyl-1H-3-benzazepin-al-hemimaleate) ([3H]SCH 23390) as a ligand. The affinity and the pharmacological profile of [3H]7-OH-DPAT and [3H]SCH 23390 at dopamine D3 and D5 receptor, respectively, were similar in subjects of different ages. The density of dopamine D3 receptor binding sites was slightly decreased in subjects of 30-39 years in comparison with younger individuals. A remarkable loss of dopamine D3 receptor was then found between 40 and 49 years of age in comparison with younger subjects. A further slight decrease was noticeable between 50 and 59 years of age. The number of [3H]7-OH-DPAT binding sites was then stabilized after 60 years of age. The density of dopamine D5 receptor binding sites did not show age-dependent changes. The above findings indicate the occurrence of a decline in the density of lymphocyte dopamine D3 but not D5 receptor between adult and mature subjects. The possibility that dopamine D3 receptor assay in peripheral blood lymphocytes may represent a tool for investigating dopamine receptor function in aging and age-related neurological disorders is discussed.

Effect of treatment with L-deprenyl on age-dependent microanatomical changes in the rat kidney

The influence of aging and of treatment with L-deprenyl on the structure of the kidney was investigated in 24-month-cld male Sprague Dawley rats by microanatomical techniques associated with image analysis. L-Deprenyl was administrated orally for 5 months at a dose not inhibiting monoamine oxidase (MAO) B activity (1.25/mg/kg/day) and at a dose inhibiting MAO B activity (5 mg/kg/day). In 24 month-old-rats the number and the volume of glomeruli was reduced in comparison with 12-month-old rats used as reference adult animals. Vascular changes characterised by increased thickness of the tunica media, decreased size of arterial lumen and increased wall-to-lumen ratio were also noticeable in 24-month-old rats. Moreover, an increased MAO B reactivity was noticeable within glomerular tufts and renal tubules. Treatment with the low dose of L deprenyl did not cause changes in MAO B reactivity, or in the number of glomeruli, but increased glomerular volume and reduced the wall-to-lumen ratio in medium-sized renal artery branches. The dose of 5 mg/kg/day of L-deprenyl significantly decreased MAO B reactivity within both glomerular tufts and tubules, increased the number and the volume of glomeruli and countered-age-related vascular changes. The above results suggest that treatment with L-deprenyl counters to some extent microanatomical changes occurring in the kidney of aged rats. The observation that the dose of the compound inactive on MAO B activity reduces in part age dependent renal microanatomical changes, indicates that the renal protective effect of L-deprenyl is only in part related to MAO B inhibition.

Pharmacological characterisation of Ca2+ channels of the L-type in human peripheral blood lymphocytes

Ca2+ channels of the L-type were characterised in intact human peripheral blood lymphocytes using a radioligand binding technique and the dihydropyridine-type Ca2+ channel antagonist [3H](+)-PN 200-110 (isopropyl-4-(2,1,3-benzoxadiazol-4-yl)1,4-dihydro-5-methoxycarbon yl-2, 6-dimethyl-3-pyridine carboxylate) as a ligand. [3H](+)-PN 200-110 binding to human peripheral blood lymphocytes was time-, temperature-, concentration-dependent and of high affinity. The dissociation constant (Kd) value was 0.4 +/- 0.02 nM and the maximum binding capacity (Bmax) was 33.5 +/- 1.6 fmol/10(6) cells. Pharmacological analysis of [3H](+)-PN 200-110 binding to human peripheral blood lymphocytes was consistent with the labelling of a Ca2+ channel of the L-type. In fact, dihydropyridine derivatives were the most potent competitors of [3H](+)-PN 200-110 binding, whereas phenylalkylamine and benzothiazepine compounds or non-selective Ca2+ channel modulators were weak or ineffective displacers. These findings are the first observation that human peripheral blood lymphocytes express Ca2+ channels of the L-type. The possibility that Ca2+ channel antagonists may interfere with immune system function is discussed.

Serotonin is involved in the ACTH-induced reversal of hemorrhagic shock in anesthetized rats

In a rat model of volume-controlled hemorrhagic shock (mean arterial pressure = 20-24 mm Hg) causing the death of all saline-treated animals within 30 min, the i.v. bolus injection of ACTH-(1-24) (160 micrograms/kg) produced an almost complete and sustained reversal of the shock condition, with recovery of arterial blood pressure, pulse pressure and respiratory rate, and with 100% survival at the end of the experiment (2 h). The serotonin-depleting agent p-chlorophenylalanine (316 mg/kg i.p., administered 66-70 h before hemorrhage) almost completely prevented the effect of ACTH. The 5-HT1/5-HT2 receptor antagonist, methysergide, prevented the effect of ACTH completely when injected i.v. (5 mg/kg), but only in part when injected into a brain ventricle (i.c.v.) (15 micrograms/rat); the 5-HT2 antagonist, ketanserin, prevented the effect of ACTH completely when injected i.c.v. (1.5 micrograms/rat), but only in part when injected i.v. (0.5 mg/kg); the 5-HT3 antagonist, MDL 72222, largely prevented the effect of ACTH when injected i.c.v. (10 micrograms/rat), but had no influence at all when injected i.v. (3 mg/kg); finally, the 5-HT4 antagonist, GR 125487, had no effect when injected i.v. (5 micrograms/kg) or when injected i.c.v. (30 ng/rat). Overall, these data indicate that both CNS and peripheral serotonin play an important role in the complex mechanism of the ACTH-induced hemorrhagic shock reversal.

Protective effect of nicardipine treatment on cerebrovascular microanatomical changes in spontaneously hypertensive rats

1. The effect of long-term treatment with the dihydropyridine Ca2+ antagonist, nicardipine, on the morphology of different sized pial arteries was assessed in spontaneously hypertensive rats (SHR) using histological techniques associated with image analysis. 2. In control 20 week old SHR blood pressure values, the thickness of the tunica media, the media-to-lumen ratio and connective tissue content were significantly increased in comparison with reference normotensive Wistar-Kyoto (WKY) rats. 3. Treatment for 8 weeks with a daily dose of 3 mg/kg of nicardipine decreased blood pressure values in SHR and significantly reduced the area occupied by the tunica media and the media-to-lumen ratio. This effect was observed primarily in small sized pial arteries and to a lesser extent in medium sized pial arteries. Nicardipine administration was without effect on connective tissue content in the wall of cerebral arteries. 4. These results indicate that treatment with nicardipine reduces blood pressure elevation in SHR and exerts a protective effect on arteries controlling cerebrovascular resistance. The activity of the compound primarily on small sized pial arteries may protect the brain from generalized vasodilation which could cause cerebral hypoperfusion.

Influence of long-term treatment with the dihydropyridine-type calcium antagonist nicardipine on renal microanatomical changes in spontaneously hypertensive rats

1. The influence of hypertension and treatment with the dihydropyridine-type Ca2+ antagonist, nicardipine, on the structure of the kidney was assessed in spontaneously hypertensive rats (SHR) of 12 weeks of age. Treatment went for 8 weeks with a daily oral dose of 1 mg/kg of nicardipine. 2. Control SHR exhibited hypertension and microanatomical vascular and glomerular changes. Vascular changes consisted of a thickening of the tunica media and decreased luminal area of medium- and small-sized intrarenal artery branches. Glomerular changes included glomerulosclerosis and atrophy of varying degrees. 3. Administration of nicardipine significantly reduced blood pressure. The drug also decreased the thickening of tunica media and luminal narrowing of renal artery branches as well as the degree of glomerular injury in SHR. 4. These data indicate that nicardipine treatment is able to control elevated blood pressure in SHR, and to counter hypertension-dependent microanatomical impairment of the kidney. This suggests that the compound exerts a protective effect on hypertensive kidney.

Localization of calcium channels of the L-type in human epicardial arteries: a light microscope autoradiographic study

The anatomical localization of Ca2+ channels of the L-type was analyzed in sections of the human right and anterior interventricular coronary arteries by using in vitro light microscope autoradiography associated with radioligand binding techniques. [3H]Nicardipine was utilised as a ligand. Binding of the radioligand to sections of the two coronary arteries was time-, temperature- and concentration-dependent. Analysis of binding isotherms revealed a dissociation constant value of about 0.5 nM in the two arteries and maximum binding capacities of 139 +/- 6.4 fmol/mg tissue for the right coronary artery and of 173 +/- 9.5 for the anterior interventricular branch. The pharmacological profile of [3H]nicardipine binding to sections of human coronary arteries was consistent with the labelling of Ca2+ channels of the L-type. Dihydropyridine derivatives were the most powerful competitors of [3H]nicardipine binding, whereas phenylalkylamines, benzothiazepine or non-selective channel modulators were weak competitors or ineffective. Light microscope autoradiography revealed the highest density of [3H]nicardipine binding sites in the tunica media of the coronary arteries. In this layer Ca2+ channels of the L-type are located within smooth muscle cells. A lower accumulation of the radioligand occurred in the tunica adventitia, whereas no specific binding was found in the tunica intima. Study of the localization of Ca2+ channels in sections of human coronary arteries may contribute to a better understanding of the mechanism of the marked coronary dilatory activity elicited by Ca2+ antagonists demonstrable in both in vitro preparations and in vivo.

Pharmacological characterisation and autoradiographic localisation of dopamine receptor subtypes in the cardiovascular system and in the kidney

Combined radioligand binding and light microscope autoradiography techniques were used for investigating the pharmacological profile and the microanatomical localisation of dopamine receptor subtypes in the cardiovascular system and in the kidney. In superior mesenteric and renal arteries the predominant dopamine D1-like receptor belongs to the D5 (or D1b) subtype. This site is located within smooth muscle of the tunica media. The same receptor subtype predominates in the kidney, where it has a vascular and tubular localisation. The dopamine D2-like receptor subtype expressed by systemic arteries belongs to the D2 receptor subtype. It has a prejunctional and endothelial localisation. In the kidney the predominating dopamine D2-like receptor belongs to the dopamine D3 subtype. Atria but not ventricles express dopamine D2-like receptors belonging to the D4 receptor subtype. The above results suggest that in spite of the emerging complexity of the dopamine receptor profile demonstrated by molecular biology techniques, radioligand binding and autoradiographic techniques, if performed with appropriate radioligands and/or in the presence of compounds active on specific receptor subtypes, may represent a useful tool for better understanding the biological significance of peripheral dopamine receptors.

Effect of long-term treatment with the dihydropyridine-type calcium channel blocker darodipine (PY 108-068) on the cerebral capillary network in aged rats

The effects of treatment with the dihydropyridine Ca+2 antagonist darodipine (PY 108-068) on age-related changes in the cerebral capillary network was studied using alkaline phosphatase histochemistry with quantitative image analysis. The investigation was performed on male Wistar rats of 12 months (adult reference group) and 27 months. The 27-month-old rats consisted of two groups, the first of control untreated animals and the second of rats receiving an oral dose of 5 mg/kg/day of darodipine from the 21st to the 27th month. The cerebral areas examined included the frontal cortex, the occipital cortex, Ammon's horn of the hippocampus, and the dentate gyrus. The number and the average length of alkaline phosphatase-positive capillaries were decreased in old rats, when compared with adult rats. The intercapillary distance, which is considered as a sensitive parameter for capillary density was increased in aged rats in comparison to adult rats. The capillary diameter was increased slightly or unchanged in old rats. The Ammon's horn and the frontal cortex were the cerebral areas most affected by age-dependent changes of the capillary network. Treatment with darodipine increased the number and the average length of alkaline phosphatase-reactive capillaries and reduced the intercapillary distance and the diameter of cerebral capillaries in old rats. The pericapillary microenvironment of the Ammon's horn was the most sensitive to treatment with darodipine. The above results showed that treatment with darodipine is capable of counteracting some microvascular changes occurring in the brain of aged rats. This suggests that the blockade of dihydropyridine-type Ca2+ channels has a positive effect on the brain microvascular system and may counteract the impairment of pericapillary microenvironment occurring with aging.

Effect of long term isradipine treatment on the morphology of the endothelium in the aorta of spontaneously hypertensive rats

The influence of hypertension and of treatment with the dihydropyridine calcium channel blocker isradipine on the morphology of the thoracic aorta and of the aortic tunica intima were studied. Three experimental groups of male spontaneously hypertensive rats (SHR) of 10 weeks of age were used. Two groups were treated with a daily oral dose of 0.01 mg/kg or of 0.1 mg/Kg of isradipine respectively. A third group of SHR was left untreated and served as control. Age-matched normotensive Wistar-Kyoto (WKY) rats were used as a reference group. Animals were allowed to survive for 12 weeks and were killed at 22 weeks of age. Systolic pressure values which did not change in WKY rats, significantly increased in SHR as a function of age. The dose of 0.1 mg/Kg/day isradipine reduced systolic pressure to normotensive values after the first week of treatment, whereas the lower one was ineffective. The area of the wall, the area of the tunica media and the wall-to-lumen ratio of the aorta significantly increased in SHR and decreased either with the antihypertensive and non-antihypertensive doses of isradipine. Transmission and scanning electron microscope analysis of the tunica intima revealed hypertrophy of the endothelial cells with an increase in sub endothelial space in SHR. An improvement of the endothelial morphology and a decrease in sub endothelial space was noticeable in isradipine-treated SHR. Although the hypotensive dose of the compound was the most effective, the non-hypotensive dose was active was well. The above results suggest that isradipine treatment may counter structural changes of the aorta of SHR and has a protective action on the hypertension-dependent modifications of the endothelium. The endothelial effects are probably dependent only in part by the hypotensive activity of the compound.

Long term choline alfoscerate treatment counters age-dependent microanatomical changes in rat brain

1. The density of nerve cells and of silver-gold impregnated fibres were evaluated in the hippocampus and in the cerebellar cortex in adult (12-month-old) and old (24-month-old) Sprague-Dawley rats. 2. The effects of long-term choline alfoscerate (GFC) treatment (100 mg/Kg/day for 6 months) on the above parameters were investigated in old rats. 3. The number of nerve cell profiles and the area occupied by silver-gold impregnated fibres were decreased both in the hippocampus and in the cerebellar cortex in old in comparison with adult rats. 4. GFC treatment countered the age-dependent reduction of nerve cells and silver-gold impregnated fibres. The hippocampus was more sensitive than the cerebellar cortex to the activity of GFC. 5. These results suggest that GFC treatment is effective in slowing down the expression of structural changes occurring in aging brain.

Influence of treatment with L-deprenyl on the structure of the cerebellar cortex of aged rats

Treatment with L-deprenyl increases mean and maximum life span in the rat and reverses memory and learning deficits associated with old age. Since only sparse information is available concerning the influence of L-deprenyl administration on the aging brain microanatomy, we have investigated the effect of long-term treatment with L-deprenyl on the structure of the cerebellar cortex in the aged rat. The cerebellar cortex was used since it represents a useful model for assessing age-related changes in nervous system anatomy and function. Male Sprague-Dawley rats were treated from the 19th to the 24th month of age with a daily oral dose of 1.25 mg/kg or 5 mg/kg L-deprenyl. Age-matched rats were left untreated and used as a control group. Eleven-month-old untreated rats were used as an adult reference group. The density of Purkinje and granule neuron profiles as well as the intensity of Nissl's staining within the cytoplasm of Purkinje neurons were reduced in 24-month in comparison with 11-month rats. Moreover, an increased accumulation of lipofuscin was noticeable in the cytoplasm of Purkinje neurons of old rats as well as an increase in MAO-B activity in the molecular layer of the cerebellar cortex. The two doses of L-deprenyl increased the density of both Purkinje and granule neuron profiles and the intensity of Nissl's staining in the cytoplasm of Purkinje neurons and reduced lipofuscin deposition within Purkinje neurons. The lower dose of L-deprenyl caused only a slight decrease in MAO-B activity, whereas the 5-mg/kg/day dose remarkably reduced it. These results suggest that long-term treatment with L-deprenyl counters the expression of some age-related microanatomical changes in the rat cerebellar cortex. The possible independence of the effects of the compound on age-related microanatomical changes of the cerebellar cortex and on MAO-B inhibitory activity is discussed.

Protective effect of nicardipine treatment on renal microanatomical changes in spontaneously hypertensive rats

The effects of nicardipine administration on kidney morphology were studied in spontaneously hypertensive rats (SHR). Male 12-week-old SHR received an oral dose of 1 mg/Kg/day of nicardipine or vehicle for 8 weeks Age-matched Wistar-Kyoto rats were used as normotensive reference animals. At 20 weeks, the non treated SHR exhibited hypertension, albuminuria, decreased urinary sodium excretion and renal microanatomical changes. These changes were characterized by vascular alterations consisting in hypertrophy of the tunica media accompanied by a decrease of luminal surface. Glomerular changes consisting primarily in signs of glomerulosclerosis of varying degrees were noticeable in the kidneys of SHR. Treatment with nicardipine significantly reduced blood pressure and albuminuria and increased urinary sodium excretion. Moreover, hypertrophy of the tunica media and the luminal surface were decreased and increased respectively in nicardipine-treated SHR. The above results suggest that treatment with nicardipine reduces blood pressure in SHR and counteracts hypertension-dependent changes in the morphology of the kidney. The protective effect of the drug on hypertensive changes of renal microanatomy probably have functional relevance given of the influence of nicardipine treatment on albuminuria and urinary sodium excretion in SHR.

Quantitative image analysis study of the cerebral vasodilatory activity of nicardipine in spontaneously hypertensive rats

The effect of the Ca2+ channel blocker nicardipine on the circle of Willis and the different sized pial arteries was assessed in 20-week-old spontaneously hypertensive rats (SHR) using quantitative image analysis techniques. Normotensive Wistar Kyoto (WKY) rats were also used as a normotensive reference group. In SHR a significant increase of systolic blood pressure (SBP) is noticeable in comparison with WKY rats. The media-to-lumen ratio was increased in the circle of Willis arteries, large sized (diameter > than 150 microns), medium sized (diameter between 150 and 50 microns) and small sized (diameter < than 50 microns), pial artery branches. An increase in the thickness of the tunica media and a luminal narrowing was also seen in medium and small sized pial arteries of SHR in comparison with WKY rats. Treatment with an oral dose of 10 mg/Kg of nicardipine 3 h before the sacrifice significantly reduced SBP in SHR. The drug was without effect on circle of Willis and on large sized pial arteries. Moreover, treatment with nicardipine reduced the thickness of the tunica media, the media-to-lumen ratio and increased the luminal area in medium and small sized pial artery branches. These findings show that treatment of SHR with nicardipine significantly reduces SBP and causes a moderate vasodilatation of arteries regulating cerebrovascular resistance. This property may be useful in avoiding generalized or exaggerated cerebrovascular dilatation which could be accompanied by impaired brain perfusion in hypertension.

Influence of treatment with the calcium channel blocker darodipine (PY 108-068) on the morphology of pial and coronary arteries in spontaneously hypertensive rats

The present study was designed to assess the influence of treatment with the calcium channel blocker darodipine (PY 108-068) on the morphology of pial and coronary arteries in spontaneously hypertensive rats (SHR). Twelve week male SHR were used in this study. One group was treated with a daily dose of 5 mg/Kg of darodipine, while the control group of SHR was treated with placebo. Age-matched normotensive Wistar Kyoto (WKY) rats were used as a reference group. After 12 weeks of treatment the rats were sacrificed. The brains and the hearts were removed, embedded in resin, cut and used for light microscope analysis. Darodipine treatment reduced blood pressure in SHR. Morphometric analysis of different sized pial and coronary arteries revealed decreased arterial lumen in SHR in comparison with WKY rats. The area occupied by the tunica media and the media-to-lumen ratio were increased in SHR in comparison with WKY rats. In darodipine-treated rats the area occupied by the arterial lumen was increased in comparison with control SHR, whereas the area occupied by the tunica media and the media-to-lumen ratio were decreased. Pial arteries were more sensitive than coronary arteries to darodipine treatment. Medium and small sized pial and coronary arteries were most sensitive to darodipine treatment. Large-sized coronary artery branches were unaffected by pharmacological treatment. The above results suggest that treatment of SHR with darodipine is able to reduce high blood pressure and to counter the development of structural changes of pial and coronary arteries noticeable in SHR. The higher sensitivity of the cerebral vasculature to darodipine treatment is discussed.

Influence of isradipine treatment on the morphology of the aorta in spontaneously hypertensive rats

OBJECTIVE

To investigate the influence of hypertension and of treatment with the vasodilator hydralazine or with the dihydropyridine calcium antagonist isradipine on the morphology of the thoracic aorta in spontaneously hypertensive rats (SHR).

DESIGN

The systolic blood pressure (SBP), body weight and morphology of the thoracic aorta were evaluated. The ultrastructure of the smooth muscle component of the aorta and of the tunica intima were analysed by transmission and scanning electron microscopy.

METHODS

The SHR were divided into three groups: a control group, which was left untreated, and two treatment groups, one with 1 mg/kg per day hydralazine and the other with 0.1 mg/kg per day isradipine. Three age-matched groups of Wistar-Kyoto (WKY) rats were included in the study: one group was left untreated and was used as a normotensive reference group, the other two groups were treated with 1 mg/kg per day hydralazine or with 0.1 mg/kg per day isradipine.

RESULTS

The SBP did not change in the WKY rats treated with hydralazine, with isradipine or untreated, but was significantly increased in the SHR as a function of age. Both hydralazine and isradipine significantly reduced the SBP in the SHR after the second week of treatment. Light microscopy analysis of the thoracic aorta revealed thickening of the wall of the tunica media as well as an increase in the wall: lumen ratio in the SHR. Treatment with hydralazine had no effect on the morphometric parameters evaluated, whereas isradipine administration significantly reduced the thickening of both the wall and the tunica media of the aorta, and reduced the wall: lumen ratio. No significant modifications in the structure of the thoracic aorta were noticed in the hydralazine- or isradipine-treated WKY rats compared with untreated WKY rats. Transmission and scanning electron microscopy analysis demonstrated in control SHR hypertrophy of smooth muscle cells of the tunica media, an increased size and impairment of the internal elastic lamina, and a widening of the subendothelial space. Hypertrophy of the endothelium was also noticeable in the SHR. Treatment with isradipine reduced the hypertrophy of smooth muscle cells of the tunica media and the structural impairment of the tunica intima. No effect of isradipine treatment on the morphology of the aorta was noticed in the WKY rats.

CONCLUSION

The present results show that the effect of isradipine was different from that of hydralazine. Both compounds lowered the SBP, but only isradipine countered the structural changes of the aorta in the SHR. The effect of isradipine administration is particularly pronounced on the hypertension-dependent changes of endothelium. This suggests that isradipine may have a protective effect on the endothelium.

Interactions between endothelin and the dihydropyridine-type calcium antagonist nicardipine in the human renal artery: a radioligand and autoradiographic study

The interactions between dihydropyridine Ca2+ channels and endothelin were analysed using combined radioligand binding and autoradiographic techniques. Endothelin is a potent constrictor peptide of arterial smooth muscle. Endothelin-induced vasoconstriction is attenuated by dihydropyridine-type Ca2+ antagonists such as nicardipine. However, the molecular mechanisms of this effect are not yet understood. Sections of the human renal artery bound [3H]-nicardipine in a manner consistent with the labelling of dihydropyridine-type Ca2+ channels. The highest density of [3H]-nicardipine binding sites occurred within the tunica media of the renal artery, probably over smooth muscle. A lower density of [3H]-nicardipine binding sites was noticeable in the tunica adventitia, whereas no specific binding occurred in the tunica intima. Endothelin-1, from a concentration of 1 pM l-1, reduced [3H]-nicardipine binding as a function of concentration. A 10 nM endothelin concentration reduced [3H]-nicardipine binding by about 85%. The isoform, endothelin-3, had little effect on [3H]-nicardipine binding. The above findings suggest the occurrence of an interaction, probably at the receptor level, between [3H]-nicardipine binding and endothelin-1. This interaction probably accounts for the attenuation of endothelin-1-elicited vasoconstriction induced by nicardipine.

Dopamine D1 receptors are involved in the ACTH-induced reversal of hemorrhagic shock

In an experimental model of volume-controlled hemorrhagic shock causing the death of all rats within 30 min, the intravenous (i.v.) bolus injection of the adrenocorticotropic hormone fragment 1-24 (ACTH-(1-24)) (160 micrograms/kg) induced a prompt and sustained improvement of cardiovascular and respiratory function, with 100% survival 2 h after treatment. Pretreatment with either haloperidol, 300 micrograms/kg i.v. (antagonist at dopamine D1 and D2 receptors), or (R)-(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3- benzazepin-7-ol hemimaleate (SCH 23390), 50 micrograms/kg intraperitoneally (selective antagonist at dopamine D1 receptors), significantly inhibited the effect of ACTH-(1-24). A complete inhibition was produced by intracerebroventricular pretreatment with SCH 23390 (0.1 micrograms/rat). On the other hand, both i.v. and i.c.v. pretreatment with l-sulpiride (selective antagonist at dopamine D2 receptors) (25 mg/kg and 80 micrograms/rat, respectively) had only minor effects. These data suggest that the mechanism of the ACTH-induced reversal of hemorrhagic shock involves the activation of dopamine D1 receptors in the brain.

Microanatomical changes in the frontal cortex of aged rats: effect of L-deprenyl treatment

The present study was designed to assess whether treatment with L-deprenyl has any effect on the age-related microanatomical changes in the rat frontal cortex. Male Sprague-Dawley rats of 19 months of age were treated until the 24th month with an oral daily dose of 1.25 mg/kg or of 5 mg/kg of L-deprenyl. Eleven-month-old untreated rats were used as an adult reference group. The density of nerve cell profiles and of glial fibrillary acidic protein-(GFAP) immunoreactive astroglial profiles, lipofuscin accumulation within the cytoplasm of pyramidal neurons, and MAO-B reactivity were assessed. A decreased density of nerve cell profiles and an increased density of astroglial profiles as well as augmented lipofuscin deposition and MAO-B reactivity were observed in the frontal cortex of rats of 24 months in comparison with 12-month-old animals. In the frontal cortex of rats treated with 5 mg/kg/day L-deprenyl, which is a dose inhibiting MAO-B activity, the density of nerve cell and GFAP-immunoreactive astrocyte profiles is increased and decreased respectively in comparison with age-matched untreated subjects. Lipofuscin deposition is reduced. The lower dose of L-deprenyl (1.25 mg/kg/day) which did not affect MAO-B activity, decreased lipofuscin deposition but was without effect on the density of nerve cell or GFAP-immunoreactive astrocyte profiles. The above findings suggest that treatment with L-deprenyl is able to counter some microanatomical changes occurring in the frontal cortex of aged rats. Some of these effects are probably not related to the inhibitory MAO-B activity of the compound.

Influence of isradipine treatment on left ventricular and coronary vascular hypertrophy in spontaneously hypertensive rats

The purpose of this study was to ascertain if Isradipine treatment in spontaneously hypertensive rats (SHR) decreased hypertension-dependent left ventricular and coronary vascular hypertrophy. Twelve week male SHR were used in this study; one group of SHR was treated with Isradipine while the control group of SHR was left untreated. Age-matched normotensive Wistar-Kyoto rats (WKY) were utilized as a reference group. After 12 weeks of treatment rats were sacrificed. The hearts were removed and morphometric analysis was performed on the left ventricles. Isradipine treatment reduced systolic blood pressure in SHR. The heart/body weight ratio significantly increased in SHR and in Isradipine-treated SHR in comparison with WKY rats. Isradipine treatment decreased the left ventricular muscle fibre diameter and decreased the amount of focal necrosis in SHR. Different sized coronary arteries were also examined using a light microscope and an image analyzer. We found that the area occupied by the medial layer and the media-to-lumen ratio were significantly increased in comparison with WKY rats. In Isradipine-treated SHR the area of the medial layer and the media-to-lumen ratio in small and medium sized but not in large sized coronary arteries were significantly reduced in comparison with untreated SHR. The above results suggest that long term Isradipine treatment is not only able to reduce high blood pressure in SHR but is also able to counter the development of certain morphological changes often seen in the hypertensive heart and coronary arteries.

Autoradiographic localization of [3H]nicardipine binding sites in the human renal artery

In the present study the pharmacological profile and the anatomical distribution of dihydropyridine-type Ca2+ channels were analyzed in sections of the human renal artery by the use of combined radioligand binding and autoradiographic techniques with [3H]nicardipine as a ligand. The binding of [3H]nicardipine to sections of renal artery was time-, temperature- and concentration-dependent belonging, at least in the range of radioligand concentrations used, to a single class of high-affinity binding sites. The dissociation constant (KD) value was 0.3 nM and the maximum density of binding sites (Bmax) was 248 +/- 16 fmol/mg tissue. The pharmacological profile of [3H]nicardipine binding to sections of human renal artery was consistent with the labeling of dihydropyridine-type Ca2+ channels. In fact, dihydropyridine derivatives were the most powerful competitors of [3H]nicardipine binding, whereas phenylalkilamine, benzothiazepine or non-selective channel modulators were weak or ineffective competitors. Light microscope autoradiography revealed the highest density of [3H]nicardipine binding sites in the tunica media of the renal artery, probably within smooth muscle cells. A smaller accumulation of the radioligand occurred in the tunica adventitia, whereas the tunica intima did not show specific binding. These results indicate that light microscope autoradiography techniques associated with radioligand binding may represent a useful tool for analyzing the localization of receptors or targets of drug action within the arterial wall.

Structural changes in the endothelium of the femoral artery of spontaneously hypertensive rats: sensitivity to isradipine treatment

OBJECTIVE

The present study was designed to investigate the influence of hypertension and of long-term treatment with the dihydropyridine calcium antagonist isradipine on the morphology of the femoral artery in spontaneously hypertensive rats (SHR).

DESIGN

Systolic blood pressure (SBP), body weight and morphology of the femoral artery were evaluated, and the ultrastructure of the endothelium was analysed by transmission and scanning electron microscopy.

METHODS

SHR were divided into three groups, a control group which was left untreated and two isradipine treatment groups, one at 0.01 mg/kg per day and the other at 0.1 mg/kg per day. Two age-matched groups of Wistar-Kyoto (WKY) rats were included in the study; one group was left untreated and was used as a normotensive reference group and the other was treated with isradipine at 0.1 mg/kg per day. The study lasted 12 weeks.

RESULTS

SBP did not change in the WKY rats, whether treated with isradipine or not, but was significantly increased in SHR as a function of age. The lower dose of isradipine did not alter SBP in the SHR, but the higher dose brought SBP values into the normal range after the first week of treatment. Light microscopy of sections of the femoral artery did not reveal any structural differences in the five rat groups examined. Both transmission and scanning electron microscopy showed endothelial alterations in the SHR, together with thickening of the internal elastic lamina. Treatment with isradipine significantly improved the morphology of the endothelium in SHR. The higher dose was more effective, but the lower dose partly countered the hypertension-dependent changes in the morphology of the endothelium. No significant modifications to the structure of the endothelium were noticed in isradipine-treated WKY rats compared with untreated WKY rats.

CONCLUSIONS

The results show that structural changes occur in the endothelium of the femoral artery of SHR and that isradipine treatment has a protective effect. This protective effect is probably only partly dependent on the antihypertensive properties of the compound.

[The prediction of academic success/failure in a school for professional nurses]

Before being admitted to nursing schools students are very often exposed to selection tests. Use and predictivity of tests is widely debated in the literature with an overall agreement on their usefulness. Some data on the predictivity of the tests are presented, based on the final results of first year nursing students. The selection consisted of five written and one oral test (educational and previous professional qualifications were also considered). Students who performed well on oral and general information written tests reported good results on first year final examinations.

Endothelin-1 displaces [3H]nicardipine binding in sections of human renal artery

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide, the actions of which are mediated through interaction with specific ET receptors. Functional evidence has shown that the constrictor effect of ET may require extracellular Ca2+. Ca2+ antagonists of the dihydropyridine family attenuate the vasoconstriction caused by ET. However, the basis of the interactions between ET and dihydropyridine agents are not well understood. Our study was designed to assess whether different concentrations of ET-1 or ET-3 have any effect on [3H]nicardipine binding to sections of human renal artery. [3H]Nicardipine was specifically bound to sections of the human renal artery. Binding sites, which were located primarily over smooth muscle of the tunica media, showed the pharmacologic profile typical of a dihydropyridine Ca2+ channel. Increasing concentrations of ET-1, but not of ET-3, competed dose-dependently with [3H]nicardipine binding. A 1-nM concentration of ET-1 lessened specific [3H]nicardipine binding by approximately 80%. These results suggest the occurrence of an interaction in the human renal artery between dihydropyridine Ca2+ channels and ET-1. This interaction probably accounts for the inhibition of the ET-1-mediated vasoconstriction elicited by nicardipine.

Dopexamine hydrochloride in the human heart: receptor binding and effects on cAMP generation

Dopexamine hydrochloride is a synthetic catecholamine proposed for the short-term treatment of heart failure and postoperative low cardiac output. The pharmacological profile and anatomical localization of dopexamine binding were investigated in sections of right and left ventricle using [3H]-dopexamine and ligand techniques associated with light microscope autoradiography. Its effects on the 3-5-cyclic adenosine monophosphate (cAMP) generating system in membrane particles of the human right or left ventricle were also studied. [3H]-Dopexamine was specifically bound to sections of human right or left ventricle. The binding was time-, temperature- and concentration-dependent and was dissociable. The apparent equilibrium constant of dissociation was 3.5 nM. A decreased [3H]-dopexamine binding capacity from the base to the apex and ventricles was noticeable. The pharmacological profile of [3H]-dopexamine binding to sections of right or left ventricle was consistent with the labelling of both beta 2-adrenoceptors and dopamine DA-2 receptors. The most potent displacer of [3H]-dopexamine was the beta 2-adrenoceptor antagonist ICI 118,551 followed by dopamine, noradrenaline and domperidone. The beta 1-adrenoceptor antagonist metoprolol or the dopamine DA-1 receptor antagonist SCH 23390 were ineffective as displacers of [3H]-dopexamine binding. Light microscope autoradiography revealed the localization of [3H]-dopexamine binding sites within the wall of the human right and left ventricle. The density of silver grains was slightly higher in the right than in the left ventricle and showed a uniform transmural distribution across the ventricular wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacological characterization and autoradiographic localization of dopamine receptors in human epicardial arteries

The pharmacological properties and the anatomical localization of dopamine (DA) D1 and D2 receptor sites were studied in normal samples of the human right coronary and anterior interventricular arteries by assessing the effect of DA on the cyclic AMP generating system and by using combined radioreceptor binding and autoradiographic techniques. DA caused a concentration-dependent accumulation of cyclic AMP in membranes of right and anterior interventricular coronary arteries. This effect was antagonized by the selective D1 receptor antagonist SCH 23390 and by other DA receptor antagonists. D2 receptor responses negatively coupled to cyclic AMP generation were obtained by incubating membranes of coronary arteries with DA together with SCH 23390 or with D2 receptor agonists. This D2 effect was abolished by the selective D2 receptor antagonist (-)-sulpiride. [3H]SCH 23390 was bound to sections of the coronary arteries in a manner consistent with the labeling of D1 sites. Light microscope autoradiography revealed the localization of D1 sites in the medial layer of the coronary arteries. [3H]Spiroperidol, in the presence of ketanserin, was bound to sections of the coronary arteries in a manner consistent with the labeling of D2 sites. D2 receptor sites were located within the adventitia and the adventitial-medial border of the two arteries, and are probably prejunctional in nature. These findings indicate the existence of both D1 and D2 receptor sites in human right and anterior interventricular arteries. Moreover, they suggest that coronary vasodilation induced by DA or DA receptor agonists may be the result of a direct coronary vasodilatory activity.

Effect of nicardipine treatment upon cardiac hypertrophy in spontaneously hypertensive rats: a morphometric and ultrastructural study

OBJECTIVE

The present study was designed to investigate the effect of nicardipine administration upon systolic blood pressure (SBP) and cardiac hypertrophy in spontaneously hypertensive rats (SHR).

DESIGN

SBP, heart: and left ventricle: body weight ratios, the cross-sectional area of cardiocytes, and the ultrastructure of the left ventricle were evaluated.

METHODS

Ten-week old male SHR and age-matched normotensive Wistar-Kyoto rats were studied for 12 weeks. One group of SHR was treated for 12 weeks with a daily oral dose of 1 mg/kg nicardipine and another group with 1 mg/kg hydralazine; Wistar-Kyoto rats were used as a normotensive control group. Light and electron microscope techniques associated with image analysis and morphometry were used.

RESULTS

Nicardipine administration normalized SBP values and significantly reduced the heart: and left ventricle: body weight ratios. Moreover, administration reduced the cross-sectional area of cardiocytes by approximately 38% in subendocardium and by 24% in subepicardium. Hydralazine administration significantly reduced SBP values but had no effect upon heart: or left ventricle: body weight ratios or the cross-sectional area of cardiocytes. Electron microscopy showed that nicardipine treatment was able to reduce the hypertension-dependent changes in cardiac ultrastructure consisting of alternations to intercalated discs and line Z morphology as well as in the decrease of the mitochondria: myofibrils ratio.

CONCLUSIONS

The above data indicate that nicardipine administration is able to reduce SBP and to counter the development of structural and ultrastructural changes in cardiac morphology which represent a common complication of arterial hypertension.

Muscarinic cholinergic receptors in the human right coronary artery: a receptor binding and autoradiographic study

We used a combination of radioreceptor binding and autoradiographic techniques to study the pharmacological characteristics and anatomical localization of [3H]-quinuclidinyl benzilate (QNB) binding sites in the human right coronary artery. The ligand was bound to sections of the human right coronary artery in a manner consistent with the labelling of muscarinic receptors. The addition of pirenzepine or of carbachol to the incubation medium to generate displacement curves was indicative of the presence of M1 and M2 receptors in the right coronary artery. Autoradiography showed the localization of M1 sites primarily in the medial layer of the right coronary artery. M2 sites were located primarily in the adventitia. No [3H]-QNB binding sites were observed in the endothelium. A possible role of muscarinic receptors in the pathogenesis of coronary vasospasm is discussed.

Autoradiographic localization of the gamma-aminobutyric acid type A receptor agonist 3H-muscimol in the rat superior cervical ganglion

The anatomical localization of gamma-aminobutyric acid type A (GABA-A) receptor sites in the rat superior cervical ganglion was studied using combined radioreceptor binding and autoradiographic techniques. 3H-Muscimol was used as a ligand of GABA-A receptor sites. The binding was consistent with the labelling of GABA-A sites. The dissociation constant value was 6.4 nmol/l, and the maximum density of binding sites was 146 +/- 7.8 fmol/mg tissue. Light microscope autoradiography revealed the accumulation of 3H-muscimol mainly in superior portions of the ganglion. Binding sites are located primarily in the neuropil rather than within ganglionic neurons. It is probable that the sites revealed by autoradiography are involved in the inhibition of acetylcholine release from ganglionic neurons.

[Acute cholecystitis associated with calculosis of the biliary tract in a high-risk patient. Combined emergency surgical and peroperative endoscopic treatment]

Patient age (over 65), and lithiasis of the common bile duct are two factors which increase the morbidity and mortality rate in emergency surgery for biliary lithiasis. Normally, calculi in the CBD can be cleared by means of supraduodenal or transduodenal access. In both cases, however, complications are frequent in high risk patients. Treatment of gallstones can be modified to achieve a reduction in the morbidity and mortality rate. This study presents an initial survey of 4 elderly patients, presenting with acute gallbladder disease and CBD stones, treated with surgical cholecystectomy and contemporary perioperative endoscopic papillotomy and CBD clearance. The underlying rationale and the good initial results support this combined surgical and endoscopic approach.

Age-related changes in substance P and vasoactive intestinal polypeptide immunoreactivity in the rat stomach and small intestine

Immunoreactivity for substance P (SP-LI) and vasoactive intestinal polypeptide (VIP-LI) in the stomach, duodenum, jejunum and ileum of young (3-month-old), adult (12-month-old) and old (28-month-old) male Wistar rats were determined by radioimmunoassay. SP-LI and VIP-LI did not show changes in the stomach or in the small intestine portions investigated in adult in comparison with young rats. In old rats SP-LI levels were unchanged in the stomach and in the duodenum, reduced in the jejunum and increased in the ileum. VIP-LI concentrations were unchanged in the stomach, and remarkably reduced in the duodenum, jejunum and ileum of old rats. Since the two neuropeptides investigated are localized primarily within different intrinsic gastrointestinal neurons, the present findings suggest that the various populations of gastrointestinal neurons are affected in a different manner during aging.

Nicardipine and vascular hypertrophy

The effects of nicardipine administration on the morphology of coronary, renal, and pulmonary vascular trees were studied in spontaneously hypertensive rats (SHRs). Male 10-week-old SHRs received 1 mg/kg/day of nicardipine or vehicle orally for 12 weeks. Age-matched Wistar-Kyoto rats were used as normotensive reference animals. Blood pressure, heart weight, heart/body weight ratio, the area occupied by the medial layer, and area occupied by the vascular wall/area of lumen ratio increased significantly (p less than 0.001) in SHRs compared with normotensive Wistar-Kyoto rats. Nicardipine reduced blood pressure, as well as relative heart weight, the area occupied by vascular smooth muscle, and the area occupied by the vascular wall/area of lumen ratio. In addition, the size of laminae of smooth muscle of the pulmonary artery was reduced in nicardipine-treated SHRs; coronary artery branches were the most sensitive. The results of the study provide direct evidence that nicardipine reduces not only blood pressure but is also able to counteract the development of hypertension-dependent changes in the morphology of the cardiovascular system.

Autoradiographic localization of beta-adrenergic receptors in human large coronary arteries

The distribution of beta-adrenergic receptors in sections of the human right and left coronary arteries and of the anterior intraventricular branch was studied by the use of combined in vitro radioreceptor binding and autoradiographic techniques. [125I]Cyanopindolol was used as a ligand for beta-adrenergic receptors. Binding of the radioligand to sections of the three coronary arteries under study was saturable, stereoselective, reversible, and displaceable by antagonists and agonists with the rank order of potency expected for beta-adrenergic receptors. Analysis of binding isotherms indicated maximum binding capacities of 41.5 fmol/mg protein for the right coronary artery, 35.4 fmol/mg protein for the left coronary artery, and 25.7 fmol/mg protein for the anterior interventricular branch. Dissociation constants were approximately 35 pM in the arteries examined. The relative amounts of beta 1- and beta 2-receptor subtypes were as follows: 72% beta 1-receptors and 28% beta 2-receptors in the right coronary artery; 65% beta 1-receptors and 35% beta 2-receptors in the left coronary artery; 40% beta 1-receptors and 60% beta 2-receptors in the anterior interventricular branch. The results of autoradiographic analysis revealed a predominance of beta 1-receptors in the medial layer. beta 2-Receptors were localized primarily in the adventitia, in the adventitia-media border, and in the intimal layer. These results should lead to a better understanding of the mechanisms involved in the control of coronary circulation in humans.

Autoradiographic localization of octylonium bromide binding sites in the rat gastrointestinal tract

The anatomical localization of the binding sites of the spasmolytic drug octylonium bromide (OB) in the rat gastrointestinal tract was analyzed by use of light microscope autoradiography. The drug was visualized after in vitro incubation of frozen sections of the gastrointestinal tract with a 10 nM concentration of 14C-OB and after in vivo injection into the ascending, transverse, descending and sigmoidal portions of the colon. In vitro experiments demonstrated the specific accumulation of 14C-OB within the colonic and rectal smooth muscle. In contrast, no specific binding of the radiolabeled drug was noticeable in the stomach or in the small intestine. In vivo intracolonic injection of 14C-OB showed a significant accumulation of the drug in the colonic musculature 2 min after administration. The predominant localization of 14C-OB in the colonic and rectal musculature could explain its effectiveness in suppressing the amplitude and frequency of colonic contractions and in controlling the irritable bowel syndrome.

Intrinsic innervation of the rat knee joint articular capsule and ligaments

In spite of the practical importance of having a detailed knowledge of knee joint innervation to understand the pathophysiologic aspects, little information is now available concerning the density and pattern of the nerve fibres which are distributed to it. The present study has been designed to investigate the density and distribution of nerve fibres and receptor corpuscles in the knee joint articular capsule, cruciate and collateral ligaments in the rat, using the acetylcholinesterase (AChE) histochemical in toto staining technique. The investigation was performed on male Wistar rats of 3 months of age, some of which had been treated with capsaicin to deplete their afferent 'C' fibres of their content of neuropeptides. AChE-positive nerve fibres and different types of receptor corpuscle endings were found within articular capsule and ligaments. The highest density of AChE-positive nerve fibres was noticeable in the fibular collateral ligament followed by the tibial collateral ligament, the posterior cruciate ligament, the anterior cruciate ligament and the articular capsule. In the articular capsule the number of type I endings was higher than in the ligaments. The opposite is true for the other type of receptor corpuscles found as well as for nerve endings. Capsaicin treatment significantly reduced the density of AChE-positive nerve fibres in knee joint ligaments but did not affect nerve fibres in the articular capsule. Moreover, it caused the disappearance of some kind of receptor corpuscles within the collateral and cruciate ligaments. The above data collectively suggest that the AChE in toto staining technique may represent a good method for investigating joint innervation and that a significant percentage of nerve fibres supplying knee joint ligaments is represented by C fibre afferents.

Prostaglandin-stimulated recovery of the human duodenal epithelium: effects of misoprostol on ethanol damage

This study was designed to determine whether prostaglandins can stimulate the repair of human duodenal epithelium. Ten healthy volunteers were given 50 ml 40% ethanol through an endoscope onto the duodenal mucosa 1-7 cm from the pyloric sphincter; 3 min later, misoprostol (200 micrograms) or inert vehicle (5 ml) was given locally in the same way. One and 5 h later, endoscopy was repeated to evaluate the damage. The conditions of the mucosa were evaluated by endoscopy and by scanning and transmission electron microscopy in biopsies taken at time 0 and 3 min, 1 and 5 h after ethanol. The study was double-blind with a cross-over balanced design. Three minutes after ethanol administration, the duodenal mucosa showed hyperemia with hemorrhagic lesions. Under the electron microscope, the lesions were caused by vascular engorgement or red blood cell extravasation into the submucosa; the epithelium underlining lesions showed loss of superficial cells and damage to the upper layer of the mucosa. One hour after ethanol, there was a striking difference between the two treatment groups, with a substantial recovery of the duodenal epithelium in the misoprostol-treated volunteers. Although spontaneous recovery was evident in the control group, there was also a significant difference at 5 h. Our results suggest that prostaglandins are able to stimulate the recovery of the duodenal epithelium after acute damage.

The noradrenergic innervation of the ovary in old rats

The influence of ageing on the noradrenergic innervation of the ovary was studied in female Wistar rats using high pressure liquid chromatography (HPLC) with electrochemical detection and catecholamine histofluorescence techniques. Old age was accompanied by a significant decrease in ovarian noradrenaline levels. In young animals (3-month-old) noradrenergic nerve fibres were distributed primarily to blood vessels and in lesser amounts to the interstitial glands. In aged animals (24-month-old) perivascular noradrenergic fibres were reduced by more than 40%; interstitial gland nerve fibres were reduced by approximately 20%. The possibility that impaired noradrenergic ovarian innervation occurring in old age may be in some way related with age-dependent failure in reproductive activity is discussed.

Age-related changes of the noradrenergic innervation of the uterine vasculature: a fluorescence histochemical study

Age-related changes in the density of the noradrenergic perivascular plexus supplying the uterine artery and its intrauterine branches were studied in rats 4, 12 and 24 months old using the glyoxylic acid fluorescence technique. Moreover, uterine noradrenaline levels were determined by means of high pressure liquid chromatography with electrochemical detection. No changes in the density of noradrenergic innervation or in uterine noradrenaline levels were noticeable in 12 month in comparison with 4 month rats. In contrast, a significant decrease in the density of the noradrenergic perivascular plexus of uterine artery and of its intrauterine branches as well as decrease in noradrenaline concentrations of uterine horns and cervix were observed in 24 month rats. The above findings indicate an age-related impairment of uterine noradrenergic innervation.

Evidence against the existence of GABA-B receptor sites in rat cerebrovascular tree

By the use of combined radioreceptor binding and autoradiographic techniques we attempted to analyse the biochemical characteristics and the anatomical localization of GABA-B receptors in sections of rat circle of Willis and pialarachnoid arteries. 3H-GABA in the presence of 40 microM isoguvacine and 2.5 mM CaCl2 was used to label GABA-B receptor sites. Sections of rat cerebellar cortex were also processed as a reference tissue. No specific 3H-GABA binding was detectable either in radioreceptor binding or autoradiographic experiments. In contrast, the ligand was bound to sections of cerebellar cortex in a manner consistent with the labelling of GABA-B receptor sites. These findings indicate that cerebrovascular physiological responses to GABA are not linked, in the rat cerebrovascular tree, to the activation of GABA-B receptors.

Age-dependent nerve cell loss in the brain of Sprague-Dawley rats: effect of long term acetyl-L-carnitine treatment

The age dependent loss of nerve cells was investigated in 22 brain areas from young (3 month), adult (13 month) and old (25 month) Sprague-Dawley rats. As in previous studies, we observed an age-related neuronal loss primarily in the archicortex and in the hippocampus and in other subcortical structures (amigdaloid nucleus, pontine nuclei, cerebellar cortex). In sensory areas of cerebral cortex the neuronal loss was less marked. The effect of a 6 month treatment with acetyl-L-carnitine (ALCAR) on the number of nerve cells in the same brain areas was also investigated. ALCAR treatment began when the rats were aged 16 months. ALCAR treatment was able to counteract the age-dependent decrease in nerve cell number primarily in the temporal and occipital cortical areas, in the archicortex and hippocampus. The above findings suggest that long term ALCAR treatment may be effective in slowing down the age-related nerve cell loss in some rat brain areas.

Lactate dehydrogenase, succinate dehydrogenase and nucleotide tetrazolium reductase histochemical activities in the mesentric arteries and arterioles of young and old rats

Age-related changes of the metabolic characteristics of large, medium and small brances of the rat superior mesenteric artery were investigated in young (4 month) and old (25 month) male Wistar rats, using enzyme histochemical techniques. The following enzymatic activities were examined: lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH); NADPH(2)-tetrazolium reductase (NADPHD) and NADH(2)-tetrazolium reductase (NADHD). The intensity of enzymatic reactions within the tunica media of the large, medium and small branches and within the tunica intima of the large and medium branches of the artery was assessed microphotometrically. In young rats the reactivity of enzymes investigated is similar in both the tunica media and the intima with the exception of SDH which reacts stronger in the media than in the intima. LDH and NADHD displayed the most intense reaction whereas SDH reaction was less intense. In old rats LDH and NADPHD reactivity decreased, SDH reactivity increased in the intima of large and medium branches; and SDH increased in the media of large branches. The possibility is discussed that an impaired endothelial function may represent one of the most consistent phenomena of aging of the superior mesenteric artery.

Age-related changes in adrenaline content of rat splanchnic blood vessels

The influence of ageing on the adrenaline content of the superior mesenteric artery and vein, renal artery and vein and portal vein was studied in 3-month- (young), 12-month- (adult) and 24-month-old (old) male Wistar rats using radioenzymatic assay for the measurement of catecholamine levels. Adrenaline concentrations were unchanged in the vascular wall of the blood vessels examined in adult rats, but were significantly decreased in the vascular wall of the superior mesenteric, renal and portal veins of old rats. In contrast, no age-dependent changes of adrenaline levels were found in the vascular wall of the superior mesenteric or renal arteries. The possibility that the loss of adrenaline concentrations in the venous vascular wall may be in some way related to the cardiovascular impairment occurring with age is discussed.

The noradrenergic innervation of spinal cord blood vessels in old rats

The density and pattern of the sympathetic noradrenergic innervation of the extramedullary and intramedullary blood vessels of the spinal cord was studied in 3-, 12- and 25-month-old male Wistar rats using combined catecholamine histofluorescence and quantitative image analysis techniques. The study of innervation of intramedullary vessels was accomplished in spinal cord-transected rats to avoid the interference of descending spinal monoamine fibres in the observations. No age-related changes in the density of noradrenergic innervation of the anterior spinal artery or of sympathetic fibres associated with spinal cord blood vessels occurred. These results suggest that unlike perivascular noradrenergic nerves supplying the cerebrovascular tree, the sympathetic innervation of spinal cord blood vessels does not undergo age-dependent changes. It cannot be excluded that the lesser vulnerability of the spinal compared to the cerebral vascular tree to certain kinds of age-related diseases, may depend on the unchanged sympathetic trophic regulation of spinal vessels with age.

Intracerebroventricular injection of hemicholinium-3 prevents the ACTH-induced, but not the physostigmine-induced, reversal of hemorrhagic shock in rats

In rats bled to hypovolemic shock, the intracerebroventricular injection of hemicholinium-3 (20 micrograms/rat) completely prevented the shock reversal induced by the intravenous injection of ACTH (1-24) (160 micrograms/kg), but had no influence on the shock reversal induced by the intravenous injection of physostigmine (70 micrograms/kg). These data indicate that brain cholinergic neurons are involved in the anti-shock effect of ACTH-peptides, but not in that of centrally acting cholinergic drugs.

Reduced lipofuscin accumulation in senescent rat brain by long-term acetyl-L-carnitine treatment

By using fluorescence microscopy and microfluorimetric techniques, the effects of ageing and of 11 months acetyl-L-carnitine (ALCAR) treatment on lipofuscin deposition within the cytoplasm of pyramidal neurons of rat prefrontal cortex and hippocampus (CA3 field) were assessed. No lipofuscin autofluorescence was observed in the nerve cell bodies of neurons under study in young rats (3 months of age), but lipopigment had accumulated in the same nerve cells of senescent rats (22 months of age). ALCAR administration significantly reduced the accumulation of lipofuscin within pyramidal neurons of the brain areas examined.

Autoradiographic localization of vasoactive intestinal polypeptide receptors in the rat mesenteric vascular tree

By the use of combined in vitro radioreceptor binding and autoradiographic techniques, we analyzed the pharmacological properties and the anatomical localization of the vasoactive intestinal polypeptide (VIP) receptor in rat superior mesenteric artery and in medium and small mesenteric artery branches. 125I-VIP was bound by sections of rat superior mesenteric artery in a manner consistent with the labeling of specific VIP receptors, with Kd and Bmax values of 0.23 nM and 0.71 pmol/mg protein respectively. Inhibition of 125I-VIP binding with VIP and related peptides gives the following rank order of potency: VIP greater than peptide histidine methionine greater than secretin. Light microscope autoradiography reveals specific VIP binding sites within the medial layer of superior mesenteric artery and its branches. Medium and small sized vessels are richer in 125I-VIP binding sites than the larger ones.

3H-muscimol binding sites within the rat choroid plexus: pharmacological characterization and autoradiographic localization

By using combined radioreceptor binding and autoradiographic techniques, we were able to localize the GABA 'A' receptor agonist 3H-muscimol in the rat choroid plexus. Within sections of rat choroid plexus, 3H-muscimol was bound specifically with a KD of 37 nM and a Bmax of 253 pmol/mg tissue. These values are consistent with the labelling of GABA 'A' receptor sites. The autoradiographic studies demonstrated that 3H-muscimol was attached to the epithelium of the choroid plexus. The blood vessels of the plexus did not exhibit specific labelling. Examination of these data suggests the existence of GABAergic mechanisms which control cerebrospinal fluid production or flow.

Autoradiographic visualization of the GABA-A receptor agonist, 3H-muscimol in the rat uterus

In the present study the distribution of specific binding sites for the GABA-A receptor agonist, 3H-muscimol, was studied in the rat uterus using an autoradiographic technique. Specific binding sites were present in both myometrium and endometrium suggesting a dual role for GABA in this organ.

Age-related changes of the metabolic profile of rat cerebellar cortex: enzyme histochemical study

The influence of aging on the metabolic profile of cerebellar cortex was studied in young (3-month-old), adult (12-month-old) and aged (26-month-old) male Sprague-Dawley rats using enzyme histochemical techniques. The following enzymatic activities related to energy transduction were examined: lactate-(LDH) and succinate-(SDH) dehydrogenases; NADH2-tetrazolium reductase (NADHD) and alpha-glycerophosphate-dehydrogenase (GPDH). The intensity of enzymatic staining within the neuropil of molecular and granular layers as well as within the cytoplasm of Purkinje neurons of young, adult and aged animals was assessed microphotometrically. In the molecular layer LSH, SDH and NADHD levels were reduced in old rats; GPDH was decreased both in adult and old animals. In Purkinje neurons no age-related changes of the enzymatic activities under study were observed. In the granular layer LDH and GPDH showed an age-dependent loss; SDH and NADHD were unchanged. The possibility that age-related changes of the enzymatic activities under study may be due to impaired energy production mechanisms and/or represent the consequence of reduced energetic needs resulting from the documented age-dependent loss of synapses in the molecular or in the granular layers of cerebellar cortex is discussed.