Exposure to crystalline silica or treatment with chlorphentermine increases vitamin E levels in rat alveolar lavage materials.

Previous studies have shown that vitamin E may be an integral part of lung surfactant and may function to protect this material from oxidant damage. Therefore, we measured the vitamin E levels in alveolar lavage materials from rats exposed to crystalline silica or treated with chlorphentermine (CP), two treatments that are known to increase surfactant phospholipids (PL) by different mechanisms. Silica exposure leads to increased PL synthesis, and CP treatment causes a reduction in PL degradation. Two different silica preparations, HCL-washed and unwashed silica, were used because exposure to each of them leads to different degrees of phospholipidosis. Exposure to HCL-washed silica results in a more than 17-fold increase in lavage PL and protein levels and a 12.2-fold increase in the amount of vitamin E. Exposure to unwashed silica leads to an approximately 7-fold increase in PL and proteins and a 5.8-fold increase in lavage vitamin E. Following treatment of rats with CP, there is a 15- to 19-fold increase in lavage PL and proteins and a 13.6-fold increase in vitamin E. When the results are expressed as micrograms vitamin E per milligram of lavage PL or protein, there is not much difference between controls and each treatment group. Because surfactant synthesis occurs in the endoplasmic reticulum, we also measured vitamin E in lung microsomes. Both silica exposure and CP treatment also lead to 1.8- to 2.5-fold increases, respectively, in the lung microsomal levels of vitamin E. These results demonstrate that alveolar lavage vitamin E levels are elevated along with lavage PL and proteins, and lung microsomal vitamin E levels are increased following exposure of rats to silica or treatment of the animals with CP.

In vivo and in vitro reversibility of chlorphentermine-induced phospholipidosis in rat alveolar macrophages.

Chlorphentermine (CP) is a cationic, amphiphilic drug (CAD) that has been studied widely for its ability to induce phospholipidosis, a disorder characterized by excessive accumulation of cellular phospholipid and ultrastructural development of lysosomal lamellar bodies (LLBs) in the cell. The accumulation of inducing drug correlates with increasing phospholipids. In the present study, we examined the reversibility of this disorder in rat alveolar macrophages (AMs) following a 7-day treatment (30 mg/kg/day, ip). The reversibility of phospholipidosis was examined under in vivo conditions and under in vitro conditions in cell cultures for a period of up to 12 days. There was a marked reduction in cellular CP levels and phospholipid content after 4 days of recovery, both in vivo and in vitro; however, there was no indication of significant loss of LLBs. Beyond this time point, ultrastructural recovery from phospholipidosis lagged behind the biochemical recovery temporally and was somewhat less rapid in vitro than in vivo. By 12 days of recovery, AMs from both groups had recovered biochemically, but a moderate level of LLBs was still present in some AMs in the in vitro recovery group. The results of this study indicate that there are more similarities than differences when comparing the recovery of phospholipidotic cells in vitro to that occurring in vivo. We conclude that the use of cell cultures may prove valuable in studying the reversibility of CAD-induced phospholipidosis.

Chlorphentermine-induced lipidosis in the rat retina: a functional and morphological study.

Chronic administration of the cationic amphiphilic anorexigenic drug chlorphentermine to rats has previously been shown to induce extraocular and ocular lipidosis: large numbers of lipidosis-related cytoplasmic inclusions can be found in the pigment epithelium and smaller numbers in the neuroretina. In the present study, female albino Wistar rats were treated orally with chlorphentermine (30-45 mg/kg body weight) for 4-16 weeks. The animals were submitted to electroretinography, and the retinae were prepared for histological investigations. Our histological findings corresponded to previous reports. The changes in electroretinographic parameters were low. The clearest change was a reduction of the b-wave amplitude of 20% after 12 and 16 weeks of treatment compared with the values before drug treatment. The a-wave amplitude did not differ from that in the control group. Lipidosis in the neuroretina may be the reason for functional influences on the b-wave amplitude. The function of the receptor cells, which is represented by the a-wave, appeared unaffected by chlorphentermine.

Experimentally induced lipidosis in uterine and vaginal epithelium of rats.

The purpose of this study was to investigate the effects of two lipidosis-inducing drugs (the anorectic drug chlorphentermine and the tricyclic antidepressant-imipramine) upon the estrous cycle of rats and upon the morphology of the vaginal and uterine epithelia. After two weeks of continuous administration of high daily drug doses, the estrous cycle became stagnant. Ultrastructurally, the vaginal and uterine epithelia contained storage lysosomes which were filled with undigested polar lipids appearing as multilamellated material. The uterine luminal epithelium was most severely affected. The estrous cycle was abolished also by treatment with the anorexigenic drug phentermine, although this compound does not cause lipidosis. Therefore, the cessation of the estrous cycle cannot be attributed to the lipidosis as induced by chlorphentermine and imipramine; probably it is a consequence of the main actions of these psychotropic drugs. The biological basis for the exceedingly severe lipidosis in the uterine luminal epithelium is suggested to be the heavy load of polar lipids physiologically delivered to the lysosomal apparatus as long as the cycle-dependent apoptotic and autophagic processes were going on during the early period of drug treatment.

Effects of drug-induced pulmonary phospholipidosis on lung mechanics in rats.

Chronic administration of amphiphilic drugs to rats induces pulmonary phospholipidosis (P), a disease characterized by accumulation of phospholipids and large foamy macrophages in alveolar spaces. We investigated whether P induced by chlorphentermine (CPH) causes changes in lung volumes and mechanics in this species. Groups of rats were fed CPH (50 mg.kg-1.day-1) for 1, 2, 3, 5, 9, and 14 wk. After each treatment period, lung volumes and mechanics were studied in the anesthetized, paralyzed, supine rat. Partial pressure-volume (PV) curves were developed at 3 and 6 ml above functional residual capacity (FRC; PV3, PV6), followed by maximal [up to total lung capacity (TLC)] PV curves. FRC was determined by saline displacement. Lungs were then fixed for histopathological examination. A subgroup of animals was allowed a recovery period of 6 wk, after the 9 wk of CPH administration. Pair-fed rats served as controls (CTR) at each time point. Lung weight increased in CPH-treated (CPH-T) rats from 1.5 +/- 0.2 (SD) g at week 1 to 5.8 +/- 1.4 g at week 14, reflecting the development of P. TLC, FRC, transpulmonary pressure at FRC, the shape of maximal PV curves, and static expiratory lung compliance computed from maximal PV data points did not change in CPH-T rats. However, partial PV curves of CPH-T lungs (particularly PV3) were shifted downward and to the right of those of CTR at 2, 3, 5, and 9 wk, indicating increased recoil pressure in phospholipidotic lungs at these time points.(ABSTRACT TRUNCATED AT 250 WORDS)

Cationic amphiphilic drug-induced renal cortical lysosomal phospholipidosis: an in vivo comparative study with gentamicin and chlorphentermine.

Daily subcutaneous injection of gentamicin (100 mg/kg) for 2 days produced a significant decrease in the activities of alkaline phosphatase, a brush-border membrane marker, and Na+-K+ ATPase, a basolateral membrane marker, in adult rat kidney cortex. Analysis of homogenate and lysosomal fractions revealed a significant rise in the concentration of total renal cortical phospholipid, phosphatidylserine, phosphatidylcholine, and phosphatidylinositol. In the lysosomal fraction, an increase in the levels of phosphatidylglycerol and phosphatidylethanolamine was also noted. Daily, oral chlorphentermine (60 mg/kg) administration for 5 days significantly reduced renal Na+-K+ ATPase without a marked change in alkaline phosphatase. As in the case of gentamicin, chlorphentermine produced a significant elevation in phosphatidylserine, phosphatidylcholine, and phosphatidylinositol as well as total phospholipid in both the homogenate and lysosomal fractions of kidney cortex. The observed chlorphentermine- or gentamicin-induced renal phospholipidosis was associated with a significant reduction in the activity of phosphatidylinositol-specific phospholipase C. The drug-induced inhibition of phospholipase C was quantitatively equal in the renal cortical homogenate and lysosomal fractions. In addition, gentamicin significantly inhibited the activity of phosphatidylserine-phospholipase C and phosphatidylcholine-phospholipase C in renal cortical homogenate. In contrast, only the activity of phosphatidylinositol-specific phospholipase C was decreased in chlorphentermine-treated kidneys. Evidence thus indicates that the gentamicin-induced accumulation of phospholipid in renal cortical lysosomes is associated with inhibition of various forms of phospholipase C, while in the case of chlorphentermine the inhibition of different phospholipases may be involved in phospholipid accumulation.

The effect of chlorphentermine pretreatment on the toxicity of nitrogen dioxide in mice.

Chlorphentermine HCl (CP) was used to induce preexisting alveolar alterations resembling a pulmonary lipidosis in mice to study these effects on the severity and duration of nitrogen dioxide (NO2) toxicity. Results indicated that a daily dose of 120 mg/kg for 14 days produced consistent histopathologic changes characterized by an accumulation of large foamy macrophages. Male Swiss-Webster mice were divided into a control and three treatment groups. Group 1 received 120 mg/kg CP po daily for 2 weeks followed by exposure to air for 48 hr. Group 2 received 20 ppm NO2 for 48 hr via whole-body inhalation, and group 3 received 120 mg/kg CP daily for 2 weeks followed by 20 ppm NO2 for 48 hr. The fourth group served as a nontreated control and received water in place of CP and air in place of NO2. All groups were compared by morphologic evaluation of pulmonary tissues at the light and electron microscopic levels at Days 0, 1, 3, 5, and 7 after the 48-hr exposure to air or NO2. In a second experiment using the same treatment groups, thin-section light microscopy was used to count the number of type I and type II cells and macrophages. NO2 exposure alone caused deaths in 20.8 and 18.5% of the mice in the two studies, but no deaths were seen in the combination groups from both experiments. Histopathologic evaluation showed a typical cellular response to the NO2 exposure, but differences were noted between the two groups receiving NO2 on this treatment. There was increased type II cell hyperplasia and terminal bronchiolitis on Days 0 and 1 but less on Days 3 to 7 in the combination group compared to the NO2 alone group. CP treatment prior to NO2 exposure caused less terminal bronchiolar epithelial hyperplasia and less pulmonary edema than was seen in the NO2 along group. The CP treatment appeared to protect against the lethal effects of NO2 at the concentration and time of exposure used and altered the cellular repair mechanism that occurs in response to NO2 toxicity. CP treatment prior to NO2 exposure caused significantly less loss of type I cells and less increase in type II cells due to NO2 damage. The combination treatment also caused an increase in macrophages greater than that seen in either individual treatment, and this number remained increased through 5 days post-NO2 exposure, whereas the NO2 alone caused a steady increase in macrophages following the exposure until Day 3.(ABSTRACT TRUNCATED AT 400 WORDS)

Amantadine-induced lipidosis. A cytological and physicochemical study.

The purpose of this study was to test whether or not the antiviral drug amantadine induces the structural features of lipidosis in intact animals (rats) and cultured cells, and to investigate the interactions between amantadine and phospholipids. Chlorphentermine was used as reference compound. When subchronically fed to rats at a daily dosage of approximately 180 mg/kg, amantadine induced ultrastructural symptoms of generalized lipidosis, the degree of which was, however, by far less marked than that previously reported for chlorphentermine. This was paralleled by the findings on cell cultures (rat peritoneal macrophages), where the lipidosis-inducing potency of amantadine was approximately 10-fold lower than that of chlorphentermine. As to drug-phospholipid interactions, amantadine had less marked effects than chlorphentermine upon the phase transition characteristics of phosphatidylcholine and phosphatidic acid; furthermore, amantadine was approximately 10-fold less potent than chlorphentermine in displacing Ca from phosphatidylserine monolayers. The present study has revealed a parallel between the comparatively low lipidosis-inducing efficacy inherent to amantadine and the comparatively low tendency to interact with phospholipids. It is suggested that the cage-like structure of the amantadine molecule hinders an effective intercalation of the drug into phospholipid aggregates, and that this is an essential factor responsible for the low inherent efficacy of amantadine with respect to lipidosis induction.

Fusion of storage lysosomes in experimental lipidosis and glycogenosis.

This ultrastructural investigation on renal collecting duct cells and hepatocytes of rats deals with the question of whether or not lipid-storage lysosomes as induced by cationic amphiphilic compounds retain their ability to fuse with autophagosomes/autolysosomes. These were recognized by their glycogen content which was made to persist by means of acarbose, an inhibitor of lysosomal alpha-glucosidase. To induce lipidosis, rats were pretreated for several weeks with chloroquine or chlorphentermine; they then received combined treatment with the lipidosis-inducing drug plus acarbose. In renal collecting duct cells, mixed storage lysosomes displaying the features of both lipidosis and glycogenosis were found to predominate, indicating that fusion between lipid-laden lysosomes and glycogen-containing autophagosomes/autolysosomes was efficient. Hepatocytes also displayed some mixed storage lysosomes; these were, however, regularly accompanied, within a given hepatocyte, by greater numbers of pure lipidosis-related inclusions and pure glycogen vacuoles. This observation indicates that in hepatocytes lipid-storage lysosomes were rather reluctant to fuse, thus displaying a feature of telolysosomes which are no longer capable of participating in cellular digestion.

Newborn response to cationic amphiphilic drugs.

Administration of various cationic amphiphilic drugs in utero results in induction of a phospholipid storage disorder in many tissues, particularly in lungs. In addition to the phospholipidosis in utero, drug exposure results in toxicity to the offspring; newborn rats die within 48 h of birth. Although drug-induced pulmonary pathological changes appear to be involved in the observed mortality, this relationship remains unclear. In contrast to mammals, administration of cationic amphiphilic drugs to the chick embryo seems not to induce phospholipid storage in the tissues examined. Treatment of newborn rats directly with these drugs also induces phospholipidosis in several tissues including lung and kidney; however, mortality does not occur. Concurrent administration of phenobarbital and chlorphentermine reduces or prevents amphiphilic drug-induced phospholipid storage in newborn rat lung and kidney. Modification of chlorphentermine actions by phenobarbital may be caused by alterations in amphiphilic drug excretion, metabolism, and catabolic phospholipase activity. Evidence thus indicates that regardless of age, animals appear susceptible to the effects of cationic amphiphilic drugs; however, species and tissues examined, as well as specific drug administration, play an important role in the observed qualitative and quantitative responses.

Prevention of chlorphentermine-induced pulmonary phospholipidosis in rats by phenobarbital.

It has been shown previously that the induction of pulmonary phospholipidosis in rats by chlorphentermine (CP) is essentially prevented by the concurrent administration of phenobarbital (PB). This study was conducted to investigate the mechanism(s) responsible for this protection. Male Long-Evans hooded rats received either 14C-CP (30 mg/kg, ip) or both PB (30 mg/kg, po) and the 14C-CP daily for up to 1 week. Associated with the PB-induced prevention of phospholipid accumulation in the lungs was an 84% reduction in CP content in the tissue. Excretion in urine and feces was 55 and 6%, respectively, of the administered 14C for the CP group, and 66 and 11%, respectively, for the CP + PB group. Increased urinary excretion was not due to enhanced glomerular filtration or urine output. With each group, nearly 80% of the 14C was extracted into ether from alkalinized urine and co-chromatographed on TLC with pure CP. The difference in nonextractable 14C (presumably polar metabolites of CP) between the two groups is small and cannot account for the difference in total 14C excreted in the urine. All of the fecal 14C was CP. These experiments rule out an increase in CP metabolism as the primary basis for the CP-induced enhancement in 14C excretion. PB appears to actually protect against CP-induced pulmonary phospholipidosis rather than reversing it. This occurs by an enhancement in excretion of CP, thereby preventing it from reaching levels in the lungs which lead to PL accumulation.

Gentamicin or chlorphentermine induction of phospholipidosis in the developing organism: role of tissue and species in manifestation of toxicity.

Daily, s.c. injection of gentamicin (100 mg/kg) for 2 days produced a significant increase in total phospholipid content of newborn rat kidney. Separation of individual phospholipid components revealed a significant rise in renal phosphatidylserine, phosphatidylinositol and phosphatidylcholine, whereas no marked change was noted in sphingomyelin, phosphatidylethanolamine or phosphatidylglycerol. Gentamicin did not significantly alter individual phospholipid classes and total phospholipid content in newborn rat liver and lung. Daily, oral chlorphentermine (60 mg/kg) administration also elevated total renal phospholipid levels and all individual phospholipid classes except sphingomyelin. In addition, a significant rise in all phospholipid components and total phospholipid content was noted in lungs of chlorphentermine-treated newborns. In the case of rat kidney, both gentamicin and chlorphentermine produced the greatest percentage of increase in phosphatidylinositol, whereas in lung phosphatidylcholine exhibited the highest percentage of elevation in response to chlorphentermine. In newborn rat liver, chlorphentermine did not induce alterations in individual and total phospholipid content. Gentamicin or chlorphentermine (1 mg/egg) failed to induce a phospholipidosis in chick embryo kidney and liver. Evidence suggests that drug-induced phospholipidosis is both species- and tissue-dependent and that this metabolic phenomenon is associated with inhibition of lysosomal phospholipases.

Alterations in monoamine oxidase activity after single and repeated exposure of rats to chlorphentermine.

Monoamine oxidase (MAO) activity was determined in rat tissues following in vivo treatments with chlorphentermine (CP). Oxidation of seven amine substrates by liver, lung or brain mitochondrial MAO was investigated at 2 h after a single i.p. injection (60 mg/kg) or after repeated injection (once daily for 3 days, 20 mg/kg, i.p.). Deamination of the type A substrates, norepinephrine, serotonin and octopamine, was decreased significantly in liver, lung and brain after both single and repeated injections. Oxidative deamination of tyramine and dopamine (type A + B substrates) was also lowered in all organs after single and repeated exposure to CP, but to a lesser degree than the type A substrates. However, oxidation of the type B substrates, benzylamine and tryptamine, was unaffected by CP administration in comparison to control. These data indicate that CP is a specific inhibitor of mitochondrial MAO, form A.

Corneal lipidosis in rats treated with amphiphilic cationic drugs.

The purpose of this study was to investigate whether generalized lipidosis experimentally induced by cationic amphiphilic drugs in rats is regularly associated with lipidotic alterations in the cornea. After chronic oral treatment with chlorphentermine, iprindole, or tamoxifen all animals showed clear lipidosis-like alterations in corneal cells. After chronic oral treatment with chloroquine and quinacrine the results were variable and unpredictable; however, consistent lipidosis-like alterations were found when chloroquine was applied locally onto the cornea. The present results show that basically the cornea of rats is involved in drug-induced lipidosis. For toxicological studies it must be kept in mind, however, that the reactions of rat cornea may be unreliable and less marked than in the cornea of human beings.

Neonatal toxicity in rats following in utero exposure to chlorphentermine or phentermine.

The administration of chlorphentermine (30 mg/kg) to pregnant rats during the last 5 days of gestation resulted in the development of a phospholipidosis in the lungs of the dams. The disorder developed in utero, as the phospholipidosis was evident in the lungs of the neonates when examined at 12 h postpartum. In contrast, a phospholipidosis was not observed in the lungs of the dams or neonates following phentermine treatment (30 mg/kg). Concurrently, neonates of the chlorphentermine-treated dams displayed a significant decrease in body weight in comparison to controls. Between 16 h and 24 h postpartum, 83% of the neonates of chlorphentermine-treated dams died. Cross-fostering and starvation experiments revealed that the lethality was not due to aberrant maternal behavior by the chlorphentermine-treated dams or malnutrition of the neonates. Histological examinations revealed endothelial and septal alterations in the lungs of neonates from chlorphentermine-treated dams. No signs of toxicity, as evidenced by the maintenance of body weight, or lethality were observed in the neonates of the phentermine-treated dams.

Modification by phenobarbital of chlorphentermine-induced changes in lung morphology and drug-metabolizing enzymes in newborn rats.

Treatment of newborn rat pups with 60 mg/kg.d chlorphentermine for 7 d produced on accumulation of alveolar foam cells accompanied by an increase in relative pulmonary tissue weight. In contrast, administration of 20 mg/kg.d for 1 wk did not markedly alter lung ultrastructure or weight in newborns. Both doses of chlorphentermine elevated the activity of pulmonary aminopyrine N-demethylase but not that of aniline hydroxylase. The increase in relative liver weight was associated with stimulation of the activities of aniline hydroxylase and aminopyrine N-demethylase in newborns administered either chlorphentermine dose. Phenobarbital treatment produced an increase in relative liver weight accompanied by elevated activities of pulmonary aminopyrine N-demethylase and hepatic aniline hydroxylase and aminopyrine N-demethylase. Simultaneous barbiturate and chlorphentermine administration produced stimulation in liver enzymes to the same extent as phenobarbital alone. In contrast, phenobarbital potentiated the chlorphentermine-induced rise in pulmonary aminopyrine N-demethylase. In the case of 60 mg/kg chlorphentermine and barbiturate, the observed potentiation of lung enzyme activity was associated with a reduction in the number of alveolar foam cells. The results suggest that chlorphentermine and phenobarbital stimulate drug-metabolizing enzyme in lung and liver of newborn rats and that phenobarbital may provide protection against phospholipidosis through stimulation of pulmonary, drug-metabolizing enzymes.

Modification by hyperoxia of chlorphentermine- or phentermine- induced effects on newborn rat lung morphology and metabolism.

Treatment of newborns with 20 mg/kg/day chlorphentermine orally for 1 week increased incorporation of thymidine into lung DNA without an associated change in tissue morphology or cyclic AMP levels. An increase in chlorphentermine dose to 60 mg/kg resulted in an accumulation of alveolar hypertrophic macrophages and a rise in incorporation of thymidine into lung DNA; however, cyclic AMP levels were decreased. In contrast, 20 or 60 mg/kg/day for 1 week phentermine-induced depression in the incorporation of thymidine into pulmonary DNA was accompanied by a decrease in cyclic AMP but no apparent alteration in tissue morphology. Hyperoxia did not modify the phentermine-induced changes in cyclic AMP levels and pulmonary ultrastructure. In contrast, hyperoxia altered the responsiveness of newborns to 20 mg/kg chlorphentermine as evidenced by the presence of foam cells. Data suggest that the chlorphentermine-induced increase in DNA synthesis in newborn lung seems independent of changes in cyclic AMP and tha modification of drug-induced alterations by hyperoxia may be related to the chemical structure of a compound.

Drug-induced lipidosis and the alveolar macrophage.

The alveolar macrophage is the principal component of the defense mechanisms of the lung. As a result, alterations in its function can predispose the host organism to pulmonary disease or damage. This cell shows toxic responses to a wide variety of chemicals which are delivered to the lungs by either inhalation or via the systemic circulation. In this regard, this review will focus on the effects of a group of cationic amphiphilic drugs which when administered to humans and animals causes a lysosomal storage disorder of lipids, principally phospholipids, in alveolar macrophages. The susceptibility to the disorder is species-dependent and can be induced in fetal, neonatal and adult animals. Evidence exists that the accumulation of lipids within the cells occurs as a result of an impairment in lipid catabolism, however, not all of the available data are consistent with this theory. In light of this, other mechanisms to explain the etiology of this lipidosis are discussed. Associated with the increase in lipid content within the cell, striking morphological, biochemical and functional changes occur to the alveolar macrophage. Available data indicate that afflicted cells have an increased phagocytic activity and exhibit enhanced killing of one strain of bacteria. While these data suggest an enhancement in certain cellular functions, inadequate information presently exists to allow conclusions to be drawn concerning the consequences of this disorder.