Effect of long-term treatment with L-deprenyl on the age-dependent microanatomical changes in the rat hippocampus.

Chronic treatment with L-deprenyl increases both mean and maximum life span and improves cognitive functions in the aged rat. The present study was designed to evaluate whether long-term treatment with L-deprenyl at a dosage not inhibiting the monoamine oxidase-B (MAO-B) (1.25 mg/kg/day) or inhibiting the enzyme activity (5 mg/kg/day) had any effect on the age-dependent microanatomical changes in the rat hippocampus. The hippocampus was chosen in view of its key role in learning and memory functions. Treatment with L-deprenyl started at 19 months and lasted until the 24th month of age. Age-matched untreated rats were used as a control, whereas 11-month-old rats were used as an adult reference group. The number of nerve cell and glial fibrillary acidic protein-immunoreactive astrocyte profiles in the CA1 and CA3 fields of the hippocampus and in the dentate gyrus was decreased and increased, respectively in aged compared with adult rats. Treatment with 5 mg/kg/day, but not with 1.25 mg/kg/day L-deprenyl increased the number of neuronal profiles and decreased the number of astrocytes in the hippocampus of aged rats. The density of zinc stores in the associative intrahippocampal pathway of mossy fibres, which was decreased in aged animals, was increased after treatment with the two doses of L-deprenyl. Lipofuscin accumulation within the cytoplasm of pyramidal neurons of the hippocampus was reduced dose dependently by L-deprenyl treatment. These results suggest that long-term treatment with L-deprenyl is able to counter the expression of age-dependent microanatomical changes in the rat hippocampus. These effects seem only partially correlated with the MAO-B inhibitory activity of L-deprenyl.

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.

Influence of long-term treatment with L-deprenyl on the age-dependent changes in rat brain microanatomy.

The present study was designed to assess whether treatment with the monoamine oxidase-B (MAO-B) inhibitor L-deprenyl, which has been documented to increase both mean and maximum survival in aged rats as well as sexual performance and cognitive function, has any effect on the age-related microanatomical changes occurring in the rat brain. Male Sprague-Dawley rats received a subcutaneous injection of 0.25 mg/kg L-deprenyl every other day from the 19th to the 24th month of age. Age-matched control rats were injected with saline, whereas 11-month-old untreated rats were used as an adult reference group. Both body and brain weight were increased as a function of age, and they were unaffected by treatment with L-deprenyl. The density of nerve cell profiles in the frontal cortex, in the CA-1 and CA-3 subfields of the hippocampus, in the dentate gyrus and in the cerebellar cortex were decreased in aged rats in comparison with adult rats. The density of nerve cell profiles in the above brain areas of L-deprenyl-treated rats was not significantly higher in comparison with age-matched control animals with the exception of Purkinje neuron profiles. The intensity of Nissl's staining, which may be related to the protein synthetic capabilities of nerve cells, is reduced within pyramidal neurons of the hippocampus and Purkinje neurons of the cerebellar cortex of aged rats. The intensity of Nissl's staining in L-deprenyl-treated rats was not different from adult rats. Lipofuscin deposition was significantly increased within the cytoplasm of pyramidal neurons of the frontal cortex, of the CA-3 subfield of the hippocampus and of Purkinje neurons of the cerebellar cortex. L-Deprenyl administration decreased lipofuscin accumulation within the cytoplasm of the above mentioned nerve cell types. The density of sulphide-silver staining in the intrahippocampal pathway of mossy fibres, which participate in the elaboration of passive avoidance responses, is decreased in aged rats. Treatment with L-deprenyl counters this age-related reduction. The above results suggest that long-term treatment with L-deprenyl is able to counter the expression of some microanatomical changes typical of aging brain.

Beta 2-adrenoceptor blockade is the basis of guinea-pig bronchial hyper-responsiveness to leukotriene C4 and other agonists.

Four beta-adrenoceptor antagonists, namely (-)-propranolol, (+)-propranolol, ICI-118551 and (+/-)-practolol, were investigated for their effects on leukotriene C4 (LTC4)-induced bronchoconstriction in the anesthetized guinea-pig. (-)-Propranolol was also investigated for its effects on acetylcholine and histamine bronchospasm in the anaesthetized guinea-pig, and on LTC4-induced contractions of guinea-pig isolated trachea and lung parenchyma. The various beta-adrenoceptor antagonists potentiated, dose-dependently, the bronchoconstriction induced by threshold doses of LTC4 and the intensity of the potentiation correlated with the beta 2-blocking capacity possessed by the drugs. (-)-Propranolol potentiated the bronchospasm induced by threshold doses of acetylcholine and histamine but to a lesser degree than the LTC4-induced bronchospasm. The airway hyper-responsiveness induced by (-)-propranolol was unaffected by pretreatment with mepyramine, cyproheptadine, phenoxybenzamine, atropine or indomethacin. The airway hyper-responsiveness induced by (-)-propranolol persisted even in adrenalectomized or reserpine-treated guinea-pigs, although adrenalectomy induced some increase in airway responsiveness. (-)-Propranolol had no effect on LTC4, histamine and acetylcholine-induced contractions of isolated trachea and lung parenchyma. The results show that the airway hyper-responsiveness induced by beta-adrenoceptor antagonists generally correlates with their beta 2-blocking activity. The possibility remains that some other unknown mechanism(s) may also be implicated.

The involvement of the release of nitric oxide in the pharmacological activity of the new furoxan derivative CHF 2363.

1. The mechanism of action and the pharmacological effects of the new furoxan derivative, CHF 2363 (4-ethoxy-3-phenylsulphonylfuroxan), were investigated. 2. Pre-incubation of CHF 2363 with human platelet-rich plasma produced a concentration-dependent inhibition of the platelet aggregation induced by collagen, adenosine diphosphate (ADP) and platelet activating factor (PAF). The test compound was about 5 times more potent than sodium nitroprusside. 3-Isobutyl-1-methyl-xanthine (IBMX) potentiated the antiaggregating effect of CHF 2363. 3. CHF 2363 was a potent inhibitor of rubbed endothelium rabbit aortic ring contraction induced by noradrenaline. Comparison of IC50 values showed that CHF 2363 was as potent as glyceryl trinitrate (GTN). 4. Increasing concentrations of CHF 2363 elevated platelet guanosine 3':5'-cyclic monophosphate (cyclic GMP) levels. Adenosine 3':5'-cyclic monophosphate (cyclic AMP) levels were unaffected. 5. Oxyhaemoglobin reduced all the pharmacological actions of the test compound. Moreover, CHF 2363 concentration-dependently released nitric oxide (NO) in platelet-rich plasma. The NO release was correlated to its ability to increase platelet cyclic GMP levels. 6. After exposure of rat aortic strips to supramaximal concentrations of GTN (550 microM), the vasorelaxant activity of CHF 2363 did not change, although that of GTN decreased about 55 fold. 7. It has been concluded that the new furoxan derivative CHF 2363 exerts a potent antiaggregating and vasorelaxant activity via NO release and increase of cyclic GMP levels. No in vitro cross tolerance between GTN and CHF 2363 was observed.

Cardiovascular effects induced by the injection of a new nonionic contrast medium (Iopamidol): experimental study in dogs.

The hemodynamic effects induced by the injection in the pulmonary artery of the new nonionic water soluble contrast medium Iopamidol were compared with those obtained by the injection of two other currently used contrast media (meglumine diatrizoate and sodium iothalamate). The experiments were carried out in nine mongrel dogs. Hemodynamic variables were continuously measured prior to, during, and for 8 minutes after injection of the contrast media. Injections of iopamidol produced significantly smaller decreases in aortic pressure (p less than 0.01), contractile indices (p less than 0.01), and peripheral resistances (p less than 0.01), and changes in heart rate and in cardiac output were less pronounced. At 3-4 minutes after injection, an increase in Vmaxd was observed with all three contrast media, but it was significantly lower after injecting Iopamidol. The role of hyperosmolality in causing cardiovascular changes is discussed. The less significant changes induced by Iopamidol appear to be the result of its lower osmolality, which is about a third that of meglumine diatrizoate or sodium iothalamate.

Neuroanatomy of aging brain. Influence of treatment with L-deprenyl.

The present study was designed to assess the influence of long term L-deprenyl treatment on some microanatomical parameters of aging rat frontal cortex and hippocampus. Male Sprague-Dawley rats of 19 months of age were divided into three groups. Rats of the first group received an oral daily dose of 1.25 mg/kg L-deprenyl; animals of the second group were treated with an oral daily dose of 5 mg/kg L-deprenyl, whereas rats of the third group were left untreated and used as control. Treatment lasted for 5 months, and rats were sacrificed at 24 months. At this age they were considered to be old. Another group of 11-month-old rats was used as an adult reference group. The density of nerve cell profiles and of glial fibrillary acidic protein (GFAP) immunoreactive astrocytes was decreased and increased respectively in the frontal cortex and in the different portions of the hippocampus in old in comparison with adult rats. A decrease in the intensity of sulfide silver staining in the mossy fibers of the hippocampus was also observed in old rats. Moreover, a cytoplasmatic accumulation of lipofuscin was noticeable in old rats as well as a significant increase of the monoamine-oxidase (MAO) B reactivity both in the frontal cortex and in the hippocampus. A higher density of nerve cell profiles, of sulfide silver staining, and fewer astrocyte profiles were noticeable in the frontal cortex and in the hippocampus of old rats treated with 5 mg/kg/day of L-deprenyl. This dose of the compound also significantly reduced lipofuscin accumulation and MAO-B reactivity in old rats. However, the lower dose of the compound did not cause any statistically significant effect on the microanatomical parameters investigated with the exception of sulfide silver staining and lipofuscin accumulation, which were increased and decreased respectively after 1.25 mg/kg per day of L-deprenyl. The above results suggest that long-term treatment with L-deprenyl is able to counter some microanatomical changes typical of the aging frontal cortex and hippocampus in the rat. These changes seem to be in part related to the MAO-B inhibitory activity of L-deprenyl.

Beta-adrenoceptor and cyclo-oxygenase block as a tool for evoking the direct bronchoconstrictor effect of leukotriene C4 in the guinea-pig.

The intravenous administration of LTC4 to anaesthetized guinea-pigs induced dose-dependent bronchoconstriction, which was maximal at the dose of 1.6 nmol kg-1. The response was abolished by indomethacin. The maximal dose of LTC4, preceded by both (-)-propranolol and indomethacin, induced maximal, slow in onset and reversible broncho-constriction. This direct effect of LTC4 was markedly and long-lastingly antagonized by FPL-55712. The beta-blocker did not appreciably affect the systemic blood pressure changes induced by LTC4. The procedure described is suggested as a suitable tool for investigating the per se effect of leukotrienes on the guinea-pig airways in vivo, as well as the efficacy of their receptor antagonists.

CHF 2206, a new potent vasodilating and antiaggregating drug as potential nitric oxide donor.

The effects of the new 3,4-disubstituted furoxan, CHF 2206, on vascular tone, platelet aggregation and platelet cyclic 3',5'-guanosine monophosphate (cGMP) levels were investigated. The compound was a potent inhibitor of rabbit aortic ring contraction induced by norepinephrine, the stable prostaglandin F2 alpha analogue, U-46619, and KCl; this activity was independent of endothelium integrity. When pre-incubated with platelet-rich plasma, CHF 2206 potently reduced in a dose-dependent manner the aggregation induced by the threshold aggregating concentration of collagen, ADP or platelet activating factor (PAF). In the same experimental conditions, the test compound increased the platelet cGMP levels and this rise was clearly associated with the inhibition of platelet aggregation. Moreover, 3-isobutyl-1-methyl-xanthine (IBMX) 5 microM potentiated the antiaggregating activity of CHF 2206. These results indicate that the increase in cGMP plays a key role in the CHF 2206-elicited responses. Oxyhemoglobin reduced all the pharmacological actions of the test compound. This evidence, along with the capacity of CHF 2206 to cause inorganic nitrite production in the presence of platelet-rich plasma, strongly suggests that nitric oxide (NO) may be a common reactive intermediate responsible for the effects induced by the drug. In conclusion, the furoxan derivative CHF 2206 exerts a potent antiaggregating and vasodilating activity with a pharmacological profile similar to the one described for NO-donating pro-drugs.

Repeated administrations of (-)-deprenyl increase [3H]MK801 binding in rat brain and antagonize the impairment of passive avoidance conditioning induced by N-methyl-D-aspartate receptor antagonists.

Repeated but not single administrations of the MAO type B inhibitor (-)-deprenyl (1 mumol/kg s.c. for 21 consecutive days) antagonized the impairment of passive avoidance retention induced by the N-methyl-D-aspartate (NMDA) receptor antagonists 2-amino-5-phosphonovalerate (APV), ketamine and dizocilpine (MK801), in rats. In well-washed membranes prepared from the hippocampi of rats repeatedly treated with (-)-deprenyl, the [3H]MK801 specific binding was increased. In contrast, repeated MAO B-selective doses of pargyline or (+)-amphetamine, as well as single injections with (-)-deprenyl failed to change [3H]MK801 binding. It is suggested that the effects of repeated (-)-deprenyl administrations upon NMDA receptors and upon the impairment of acquisition of a passive avoidance task induced by NMDA antagonists could be independent of MAO inhibition.

Deficits in cholinergic neurotransmission markers induced by ethylcholine mustard aziridinium (AF64A) in the rat hippocampus: sensitivity to treatment with the monoamine oxidase-B inhibitor L-deprenyl.

Assessment was made of the effects of intracerebroventricular (i.c.v.) administration of ethylcholine mustard aziridinium (AF64A) and of the monoamine oxidase (MAO)-B inhibitor L-deprenyl on the acetylcholine (ACh) biosynthetic enzyme choline acetyltransferase (ChAT), on the ACh catabolic enzyme acetylcholinesterase (AChE) and on the density of ACh muscarinic M-1 and M-2 receptor sites. In addition, the effect of AF64A and of L-deprenyl treatment on the localization of AChE activity in the CA-1 and CA-3 fields of the hippocampus was evaluated by combined enzyme histochemistry and microdensitometry techniques. I.c.v. injection of AF64A induced, 4 weeks after administration of the neurotoxin, a remarkable increase of MAO-B activity, and a significant reduction of ChAT and AChE activities in the hippocampus but not in the neostriatum which was used as a reference tissue. Hippocampal muscarinic M-1 receptors were unaffected by AF64A administration, whereas M-2 sites were reduced after neurotoxin injection. Enzyme histochemistry analysis showed that the loss of AChE induced by AF64A was more pronounced in the CA-3 than in the CA-1 field of the hippocampus. Treatment with L-deprenyl induced, from a dose of 11.17 microM/kg/day, a significant reduction of MAO-B activity in the hippocampus. The expression of ChAT and AChE, as well as the density of M-2 receptors, was increased after L-deprenyl administration in the hippocampus but not in the neostriatum. An increase in AChE reactivity was noticeable in the CA-1 and CA-3 fields of the hippocampus of AF64A-injected rats treated with L-deprenyl.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantification of the synergism between fenoterol and ipratropium bromide in the counteraction of experimental bronchospasm.

The interaction between the beta 2-agonist fenoterol and the antimuscarinic ipratropium bromide in the counter-action of experimental bronchospasm in the guinea-pig was studied qualitatively and quantitatively. Finney's analysis showed a significant overadditive interaction between the two constituents of the association, the 'overadditivity factor' being 2.15 if calculated on the peak activity or 2.68 if calculated on the area under the curve inhibition-time. In addition, the combination possesses both of the advantages of the two components, namely rapid onset of action (characteristic of the beta-agonist) and long duration of action (characteristic of the antimuscarinic). A study of the principal cardiovascular and hemodynamic parameters in the cat ruled out any synergism between the two drugs at these levels.

[Creatine phosphokinase release from perfused cardiac muscle under hypoxic conditions. Effect of propranolol, verapamil, reserpine and deslanoside]. / Rilascio di creatinfosfochinasi dal muscolo cardioaco perfuso in condizioni ipossiche. Effetto del propranololo, verapamil, reserpina e deslanoside.

Experiments were undertaken to determine if some drugs (propranolol, reserpine, verapamil and deslanoside) have an effect on CPK release from hypoxic heart muscle. Hypoxia was induced in isolated Langerdorff perfused rabbit hearts by gassing the perfusate with 95% N2 + 5% CO2. Hypoxic induced damage of the rabbit heart muscle has been quantited in terms of the relase of the intracellular enzymes creatinephosphokinase (CPK) into the extracellular space. Propranolol was either added at the start of the hypoxic perfusion or the rabbit were pretreated with it. Verpamil, dl-propranolol and reserpine provided protection evidenced by a reduction of hypoxic induced CPK release, while lanatoside C and d-propranolol failed to prevent the hypoxic muscle from releasing CPK.

Cardiovascular effects of nicardipine in anesthetized open-chest dogs in the absence and presence of beta-adrenergic receptor blockade: a comparison with nifedipine and verapamil.

Nicardipine, a new 1,4-dihydropyridine calcium-entry blocker, was assessed for cardiovascular effects against nifedipine and verapamil in anesthetized open-chest beagle dogs, in the absence and presence of beta-adrenoceptor blockade (propranolol 1 mg/kg i.v.). In control conditions, intravenous nicardipine and nifedipine (30 nmol/kg) produced decreases in blood pressure of similar magnitude without evidence of cardiodepression. An equihypotensive dose of verapamil (300 nmol/kg), by contrast, induced long-lasting negative chronotropic and inotropic effects, which, when combined with the effects of propranolol, were so marked as to cause the death of two of five dogs (atrioventricular block). Dihydropyridine derivatives at higher doses (100 nmol/kg) produced different responses: nifedipine depressed cardiac performance significantly more than nicardipine and, in the presence of beta-adrenergic blockade, caused the death of three of six dogs due to cardiovascular failure. In the nicardipine group, on the contrary, cardiac function was adequately preserved even in the presence of beta-blocker, and no animals died. The results of the present study confirm a previous in vitro observation: nicardipine is a calcium-entry blocker devoid of remarkable cardiodepressant effects and particularly selective for the vascular smooth muscle.

In vitro effects of nicardipine on vascular and cardiac muscle preparations.

Nicardipine, a new 1,4-dihydropyridine derivative with Ca++-antagonist activity, was tested on rabbit aortic strips contracted with K+ and NA, and on an isolated guinea pig heart perfused at constant flow. It inhibited K+-contraction in the aortic strips and reduced coronary resistance with the same potency as nifedipine resulting about 10 time less potent than the latter in depressing the myocardial contractility. The effects of nicardipine appear to be related essentially to its Ca++-antagonist activity rather than to any antiphosphodiesterase activity.

Regional vasodilating and cardiac effects of nicardipine in anaesthetized open chest dog.

In this study the effects of intravenous nicardipine on the cardiovascular system in anaesthetized open chest dogs were assessed. In the dose range of 3-30 nmol/kg it induced a dose-dependent and long lasting reduction of the vertebral, coronary and femoral vascular resistance. Nicardipine proved to be equipotent, but longer lasting than nifedipine, and about 10 and 100 times more potent than verapamil and papaverine respectively. Unlike papaverine, calcium entry blockers caused a preferential vasodilation of the vertebral and coronary arteries. Hypotension and a reduction of LVSP and dP/dt appeared only at the highest dose tested. However, for both dihydropyridine derivatives, in contrast to verapamil, the cardiodepressant effects were short-lived and resulted less marked for nicardipine than for nifedipine.

Inhibition of parathyroid hormone-stimulated resorption in cultured fetal rat long bones by the main metabolites of ipriflavone.

Ipriflavone is an isoflavone derivative used in the prevention and treatment of postmenopausal and senile osteoporosis in humans. To assess the potential contribution of the main in vivo ipriflavone metabolites (M1, M2, M3, and M5) on the pharmacological properties of the drug, we investigated their effect on osteoclastic resorption induced by the well-known stimulator of bone resorption bovine parathyroid hormone fragment 1-34 (bPTH 1-34). The study was carried out using fetal rat long bones in stationary cultures. The amount of osteoclastic resorption was determined by assaying for 5 days the release from bones in the media of previously incorporated 45Ca. All metabolites were effective at inhibiting osteoclastic resorption. Maximal potency was shown by M3, characterized by a significant effect at 10 microM (P < 0.01) and by an IC50 value of 17 microM. M2 was about threefold less potent than M3 (IC50 = 46 microM). M1 and M5 were the least active compounds with an IC50 value of 117 and 200 microM, respectively. The present evidence indicates that metabolites of ipriflavone, in particular M3 and M2, inhibit bPTH 1-34-induced bone resorption in fetal rat long bones. Accordingly, they may play an important role in the pharmacological effects of the drug.

Investigation of the activity of bronchodilators using a simple but accurate inhalation procedure: forced insufflation.

A simple but accurate inhalation procedure for investigating the activity of antiasthmatic drugs is proposed. The procedure consists of the forced insufflation of the powdered drug, blended with micronised lactose, direct into the tracheobronchial tree. Beta-adrenoceptor agonists (isoproterenol and fenoterol) and antimuscarinics (atropine and ipratropium bromide) were tested using the method of Konzett and Rössler in the guinea-pig; their bronchodilator effects were tested both after forced insufflation and after intravenous administration. The proposed inhalation method supplied close-response curves qualitatively comparable to those obtained by the intravenous route, with the added advantage of more detailed information on the time-course effect. Forced insufflation may be the best procedure for investigating antiasthmatic drugs intended for use as inhalants.