No increase in carcinogen-DNA adducts in the lungs of monkeys exposed chronically to marijuana smoke.

Rhesus monkeys exposed to marijuana smoke either 7 or 2 days/weeks (HI and LO groups, respectively), or ethanol-extracted marijuana smoke for 7 days/week (EM) or sham treatment (SH) for 1 year were sacrificed 7 months following the last exposure. Pulmonary levels of carcinogen-DNA adducts were determined. Although mean or median adduct levels were not statistically different, 15 of 22 adduct measures were highest in the EM group and lowest 12 of 22 times in the SH group. The levels of aromatic carcinogen-DNA adducts seem no higher in the lungs of animals exposed to marijuana smoke than in untreated animals. Ethanol-extracted marijuana may have effects greater than marijuana itself.     

Chronic marijuana smoke alters alveolar macrophage morphology and protein expression.

Male rhesus monkeys were subjected to chronic exposure to marijuana smoke. High dose animals (HI) were exposed 7 days/week to 1 MJ cigarette/day; low dose animals (LO) were exposed on 2 consecutive weekend days to 1 MJ cigarette/day; placebo animals (EM) were exposed to 1 ethanol-extracted MJ cigarette/day for 7 days/week; sham animals (SH) were exposed to sham smoking conditions 7 days/week. This regimen was maintained for 1 year and was followed by a 7 month rest period. Alveolar macrophages of animals exposed to the LO and HI dose smoking regimens exhibited irregular cell surface morphology, increased vacuolization, and a spherical conformation upon adherence to plastic. Gel protein profiles of purified macrophages from HI and LO animals showed marked differences in both constitutive and bacterial lipopolysaccharide-elicited protein expression when compared with those of macrophages from the EM or SH animals. These results indicate that chronic THC exposure alters macrophage morphology and protein expression to external stimuli even after a 7 month rest period.     

Chronic marijuana smoke exposure in the rhesus monkey. IV: Neurochemical effects and comparison to acute and chronic exposure to delta-9-tetrahydrocannabinol (THC) in rats.

THC is the major psychoactive constituent of marijuana and is known to produce psychopharmacological effects in humans. These studies were designed to determine whether acute or chronic exposure to marijuana smoke or THC produces in vitro or in vivo neurochemical alterations in rat or monkey brain. For the in vitro study, THC was added (1-100 nM) to membranes prepared from different regions of the rat brain and muscarinic cholinergic (MCh) receptor binding was measured. For the acute in vivo study, rats were injected IP with vehicle, 1, 3, 10, or 30 mg THC/kg and sacrificed 2 h later. For the chronic study, rats were gavaged with vehicle or 10 or 20 mg THC/kg daily, 5 days/week for 90 days and sacrificed either 24 h or 2 months later. Rhesus monkeys were exposed to the smoke of a single 2.6% THC cigarette once a day, 2 or 7 days a week for 1 year. Approximately 7 months after the last exposure, animals were sacrificed by overdose with pentobarbital for neurochemical analyses. In vitro exposure to THC produced a dose-dependent inhibition of MCh receptor binding in several brain areas. This inhibition of MCh receptor binding, however, was also observed with two other nonpsychoactive derivatives of marijuana, cannabidiol and cannabinol. In the rat in vivo study, we found no significant changes in MCh or other neurotransmitter receptor binding in hippocampus, frontal cortex or caudate nucleus after acute or chronic exposure to THC. In the monkey brain, we found no alterations in the concentration of neurotransmitters in caudate nucleus, frontal cortex, hypothalamus or brain stem.(ABSTRACT TRUNCATED AT 250 WORDS)     

Chronic Marijuana Smoke Exposure in the Rhesus Monkey I. Plasma Cannabinoid and Blood Carboxyhemoglobin Concentrations and Clinical Chemistry Parameters

Chronic Marijuana Smoke Exposure in the Rhesus Monkey I. PlasmaCannabinoid and Blood Carbxyhemoglobin Concentrations and ClinicalChemistry Parameters SLIKKER, W., JR., PAULE, M. G., ALI, S.F., SCALLET, A. C., AND BAILEY, J. R (1991). Fundam. Appl Toxicol17, 321–334. This report is the first in a series abouta large multidisciplinary study designed to determine whetherchronic marijuana (MJ) smoke exposure results in residual behavioraland/or neuropathological alterations in the rhesus monkey. Priorto the initiation of a year of chronic MJ smoke exposure, 64periadolescent male rhesus monkeys were trained for 1 year toperform five operant behavioral tasks and then divided, accordingto their performance in these tasks, into four exposure groups(n=15–16/group): (1) a high dose (HI) group, exposed 7days/week to the smoke of one standard MJ cigarette; (2) a lowd m (LO) group, exposed on weekend days only to the smoke ofa standard MJ cigarate; (3) an extracted MJ cigarette (EX) group,exposed 7 days/week to the smoke of one ethanol-extracted MJcigarette; and (4) a sham group (SH), exposed 7 days/week tosham exposure conditions. Daily exposures for 1 year were accomplishedusing a mask that covered the subjects' nose and mouth. Averagebody weights (initially 3.7?0.5 kg, mean?SD) and rates of weightgain (approximately 0.1 kg/month) were the same for all groupsthroughout the entire experiment. During the first week of expsure,plasma concentrations of -9-tetrahydrocannabinol and 11-nor-9-carboxy-THCin the HI group were 59?7 (mean?SE) and 5.5?1.5 ng/ml, respectively,45 min after MJ smoke administration and did not change significantlyat similar times after exposure throughout the remainder ofthe year. Whole blood carboxyhemoglobin levels increased toapproximately 13% 1 min after expsure to smoke in either theMJ or the EX groups. Comparison of blood chemistry and hematologyvalues before, during, and after exposure indicated no differencesfor most parameters. During exposure, lymphocytes, alkalinephosphatase and -glutamyl transferase were depressed in theHI group compared to in the SH group. During exposure, aspartateaminotransferase was elevatd for both the HI and EX groups,suggesting a general effect of smoke exposure. Because theseeffects were transient and remained within the range of reportednormal values, these data indicate that long-term, experimentalexperimental exposure to MJ smoke is feasible and does not compromisethe general health of the rhesus monkey.     

In utero exposure to 1R4F reference cigarette smoke: evaluation of developmental toxicity.

The potential developmental effects of 1R4F reference cigarette smoke were examined using Sprague-Dawley rats exposed for 2 h/day, 7 days/week, by nose-only inhalation at target mainstream smoke concentrations of 150, 300, and 600 mg/m3 total particulate matter (TPM). Males were exposed 4 weeks prior to and during mating, with females exposed 2 weeks prior to mating and during mating, and through gestation day (GD) 20. Sham controls received filtered air to simulate nose-only exposure, while cage controls were maintained untreated. Smoke exposure was confirmed through biomarker evaluation (parental: carboxyhemoglobin, nicotine, and cotinine; fetal: nicotine and cotinine). Characteristic cigarette smoke-related histopathologic changes including nasal epithelial hyperplasia and squamous metaplasia and pigmented macrophages in the lung were observed in all exposed parental groups. Maternal toxicity during gestation was indicated at smoke concentrations of 300 and 600 mg TPM/m3, where corrected total body weight gain was significantly (p 相似文献   

Performance of heavy marijuana-smoking adolescents on a laboratory measure of motivation

Marijuana smoking produces effects that may persist for hours or days beyond the period of acute intoxication. Despite evidence that adolescence represents a period of heightened exposure to marijuana, little research exists regarding possible impairment in adolescents who smoke marijuana regularly, and none exists regarding basic behavioral processes. In the present study, adolescents who smoked marijuana on a regular basis (near daily) were compared to a control group of adolescents on a two-option experimental task designed to measure motivation. The contingencies were arranged such that one option (work), which required systematically increasing response output, initially produced greater rates of monetary reinforcement than an alternative option (non-work) that required no response output to earn money. Switching to the non-work option was interpreted as a measure of reduced motivation. Significant differences were found between the groups: the marijuana-smoking participants switched earlier to the non-work option, and derived a greater percentage of their earnings from the non-work option. These differences existed when controlling for differences in cognitive aptitude, gender, and the presence of conduct disorder. A significant correlation between cannabinoid levels and percent of earnings derived from the non-work option suggests that these effects could be associated with the presence of cannabinoids in the marijuana-smoking group.     

Inhalation bioassay of cigarette smoke in rats

Groups of 80 female rats were exposed to cigarette smoke from three types (code 13 = high tar, low nicotine; code 27 = low tar, medium nicotine; code 32 = high tar, high nicotine) of cigarettes in Maddox-ORNL smoking machines, eight cigarettes per day, 7 days per week, for up to 24 months. An additional group received sham exposures and a fifth group served as untreated controls. The sham-exposed animals had significantly lower body weights than the untreated controls. The smoke-exposed animals had significantly lower weights than the sham-exposed controls; the weights were lower for the code 27 and code 32 animals than for the code 13 animals during the second year of exposure. The survival of the code 13 animals was similar to that for the sham-exposed and untreated control group; survival times of the code 27 and code 32 animals were shorter. Body weight and survival reflected the high- and low-nicotine dose groups indicated by in vivo dosimetry measurements. Smoke-induced histopathologic lesions consisted primarily of pulmonary smoke granulomas; the smoke granulomas were less severe in the code 27 exposure group than in the groups exposed to smoke from code 13 or code 32 cigarettes. Additional changes included pulmonary alveolar epithelial hyperplasia, and squamous metaplasia and basal cell hyperplasia of laryngeal and tracheal epithelium. One primary epidermoid carcinoma was found in the lung of a code 27 rat. The rats tolerated the chronic exposures relatively well and certain of the smoke-induced lesions allowed differentiation between the different types of cigarettes.     

Inhalation of tobacco smoke induces increased proliferation of urinary bladder epithelium and endothelium in female C57BL/6 mice

Cigarette smoking is the major environmental risk factor for bladder cancer in humans. Aromatic amines, potent DNA-reactive bladder carcinogens present in cigarette smoke, contribute significantly. However, increased cell proliferation, caused by direct mitogenesis or in response to cytotoxicity, may also play a role since urothelial hyperplasia has been observed in human cigarette smokers. We examined the urothelial effects of cigarette smoke (whole body inhalation exposure (Teague) system) in female C57BL/6 mice at various times in two studies, including reversibility evaluations. In both studies, no urothelial hyperplasia was observed by light microscopy in any group. However, in study 1, the Ki-67 labeling index (LI) of the urothelium was significantly increased in the smoke exposed group compared to controls through 3 months, but was not present at 6, 9 or 12 months even with continued exposures. In the groups that discontinued smoke exposure, it returned to the same levels as controls or lower. In study 2, the bromodeoxyuridine LI was similar to controls on day 1 but significantly increased at 5 days in the smoke exposed group. In the group that discontinued smoke exposure for 2 days, the LI was increased compared to controls but not significantly. Superficial urothelial cell cytotoxicity and necrosis were detectable by scanning electron microscopy at 5 days. Changes in LI of submucosal endothelial cells generally followed those of the urothelium and effects were reversible upon cessation of exposure. The increased urothelial proliferation appeared to be due to superficial cell cytotoxicity with consequent regeneration.     

Histological and immunohistochemical study of the expression of p53 and ki-67 proteins in the mucosa of the tongue, pharynx and larynx of rats exposed to cigarette smoke

Introduction: Head and neck cancers are linked to smoking. The most affected sites are the oral cavity, pharynx and larynx. Experimental studies show epithelial lesions caused by cigarette smoke. Objectives: To investigate in rats the effects of acute cigarette smoke exposure on the mucosa of the tongue, pharynx and larynx. Material and method: Wistar rats were allocated into two groups of 20 animals: CG (control) receiving food and water ad libitum and TG (Tobacco) exposed to the smoke of 40 cigarettes/day for 60 days. Biopsy of their tongues, pharynxes and larynxes were subjected to histopathological, histomorphometric and immunohistochemical studies of protein p53 and ki-67. Result: The histological analysis of tongue from the Tobacco group revealed epithelial hyperplasia (90%), basal cell hyperplasia (95%) and mild to moderate dysplasia (85%). In pharynx showed basal cell hyperplasia (85%), dysplasia (25%) and vascular congestion (95%). In larynx showed basal cell hyperplasia (70%), epithelial hyperplasia (55%), congestion (100%) and inflammatory infiltrate (25%). Morphometric analysis revealed that keratin layer thickness was greater in the tobacco group. P53 immunoexpression was negative in both groups. Ki-67 immunoexpression was positive in basal cell nuclei but in parabasal cell nuclei it was positive only in the Tobacco group. Conclusions: The exposure of animals to cigarette smoke for 60 days resulted in benign lesions. The duration of exposure was not enough to cause the development cancer, as confirmed by the negative expression of p53 protein in all slides examined. Analysis of ki-67 expression showed intense epithelial proliferation in response to damage.     

Alterations in prostacyclin and thromboxane formation by chronic cigarette smoke exposure: temporal relationships and whole smoke vs. gas phase

Chronic cigarette smoke exposure in vivo causes decreased conversion of [14C]arachidonic acid (AA) to prostacyclin (PGI2) by isolated aortic tissue and increased conversion to thromboxane (TXA2) by isolated platelets from rats. Alterations in the PGI2/TXA2 balance may be part of the mechanism through which smoking increases the risk of cardiovascular disease. To study the influence of smoke exposure duration on this response, male rats were exposed daily to 10 puffs of freshly generated cigarette smoke. Animals were killed after 1, 4, 14, 28 and 57 days of smoke exposure and 3, 7, 14 and 28 days after cessation of the 57-day of smoke-exposure regimen. Elevated carboxyhemoglobin levels during the smoke-exposure sessions verified smoke (gas phase) inhalation. Statistically significant alterations in prostacyclin synthesis preceded those of thromboxane. A decrease of 20-25% (P less than 0.05) in PGI2 production from [14C]AA in isolated aortic tissue was found beginning 28 days after smoke was initiated and quickly rebounded when smoke exposure was terminated. Increased production of TXA2 from [14C]AA by isolated platelets became statistically significant (P less than 0.05) on the 57th day and returned to normal 7-14 days after cessation of smoke exposure. To determine the effect of gas phase constituents on the PGI2/TXA2 balance a second series of experiments divided male and female Sprague-Dawley rats into sham, whole smoke and gas phase groups. Gas phase was produced by passing whole smoke through a Cambridge filter to remove particulate matter. Per cent COHb averaged 1.4 for sham, 7.8 for whole smoke and 9.4 for gas phase groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Biological responses in rats exposed to mainstream smoke from a heated cigarette compared to a conventional reference cigarette

Abstract

The heated cigarette (HC) generates mainstream smoke by vaporizing the components of the tobacco rod using a carbon heat source at the cigarette tip. Mainstream smoke of HC contains markedly less chemical constituents compared to combusted cigarettes. Mainstream smoke from HC was generated under Health Canada Intense regimen and its biological effects were compared to those of Reference (3R4F) cigarettes, using nose-only 5-week and 13-week inhalation studies. In the 13-week study, SD rats were necropsied following exposure to mainstream smoke from each cigarette at 200, 600 or 1000?µg wet total particulate matter/L for 1?h/day, 7 days/week or following a 13-week recovery period. Histopathological changes in the respiratory tract were significantly lesser in HC groups; e.g. respiratory epithelial hyperplasia in the nasal cavity and accumulation of pigmented macrophages in alveoli. After a 13-week recovery, the lesions were completely or partially regressed, except for accumulation of pigmented macrophages in alveoli, in both HC and 3R4F groups. In the 5-week study, SD rats were necropsied following exposure to mainstream smoke of either cigarette at 600 or 1000?µg/L for 1?h, two times/day (with 30?min interval), 7 days/week or following a 4-week recovery period. Bronchoalveolar lavage fluid (BALF) analysis of neutrophil percentages and enzyme levels like γ-GT, ALP and LDH indicated that pulmonary inflammation was significantly less in HC groups compared to 3R4F groups. In conclusion, HC demonstrated significantly lower biological effects compared to 3R4F, based on the BALF parameters and histopathology.     

Histological and immunohistochemical study of the expression of p53 and ki-67 proteins in the mucosa of the tongue,pharynx and larynx of rats exposed to cigarette smoke

Introduction: Head and neck cancers are linked to smoking. The most affected sites are the oral cavity, pharynx and larynx. Experimental studies show epithelial lesions caused by cigarette smoke. Objectives: To investigate in rats the effects of acute cigarette smoke exposure on the mucosa of the tongue, pharynx and larynx.

Material and method: Wistar rats were allocated into two groups of 20 animals: CG (control) receiving food and water ad libitum and TG (Tobacco) exposed to the smoke of 40 cigarettes/day for 60 days. Biopsy of their tongues, pharynxes and larynxes were subjected to histopathological, histomorphometric and immunohistochemical studies of protein p53 and ki-67.

Result: The histological analysis of tongue from the Tobacco group revealed epithelial hyperplasia (90%), basal cell hyperplasia (95%) and mild to moderate dysplasia (85%). In pharynx showed basal cell hyperplasia (85%), dysplasia (25%) and vascular congestion (95%). In larynx showed basal cell hyperplasia (70%), epithelial hyperplasia (55%), congestion (100%) and inflammatory infiltrate (25%). Morphometric analysis revealed that keratin layer thickness was greater in the tobacco group. P53 immunoexpression was negative in both groups. Ki-67 immunoexpression was positive in basal cell nuclei but in parabasal cell nuclei it was positive only in the Tobacco group.

Conclusions: The exposure of animals to cigarette smoke for 60 days resulted in benign lesions. The duration of exposure was not enough to cause the development cancer, as confirmed by the negative expression of p53 protein in all slides examined. Analysis of ki-67 expression showed intense epithelial proliferation in response to damage.     

Augmentation of elastase-induced emphysema by cigarette smoke: effects of reducing tar and nicotine content

The effects of reducing the tar and nicotine concentration of cigarette smoke were examined in a rat model of smoke-augmented, porcine pancreatic elastase- (PPE-) induced, pulmonary emphysema. Sixty-eight female Long-Evans rats were divided approximately evenly into seven groups: control, PPE, PPE plus sham smoke, high-tar/nicotine cigarette smoke (2R1; 38.8 mg total particulate matter and 2.2 mg nicotine per cigarette), low-tar/nicotine cigarette smoke (1R4F; 10.8 mg total particulate matter and 0.8 mg nicotine per cigarette), PPE + 2R1, and PPE + 1R4F. Three days after intratracheal administration of PPE (400 IU/kg), animals in the smoke-treated groups were exposed to 8-10 puffs of cigarette smoke daily, 7 d/wk for 12 wk. Sham-treated animals received room air in place of cigarette smoke. At the conclusion of the exposures, pulmonary function tests were performed under general anesthesia. Cigarette-smoke exposure alone did not produce significant changes in pulmonary function. Elastase-treated groups demonstrated significant increases in total lung capacity, functional residual capacity, and dynamic and static compliance, as well as significant decreases in carbon monoxide (CO) diffusing capacity and CO diffusion coefficient. Morphometric measurements of mean linear intercept demonstrated a loss of alveolar fine structure with enlargement of distal airspaces in PPE-treated rats. Exposure to either 2R1 or 1R4F cigarette smoke significantly enhanced many of the emphysematous changes produced by PPE, but there were no significant differences between the effects of the two smokes. These data indicate that reducing the tar and nicotine concentration of cigarette smoke does not lessen its ability to augment PPE-induced pulmonary emphysema in the rat.     

GLUTATHIONE LEVELS PLAY A ROLE IN CIGARETTE SMOKE-INDUCED CELL PROLIFERATION IN THE RAT LUNG

To investigate the role of glutathione (GSH), an important cellular oxidant defense mediator, in cellular proliferation induced by cigarette smoke exposure, we utilized two experimental protocols. The first protocol was designed with four groups of rats. Two groups were pretreated with diethyl maleate (DEM) to reduce tissue GSH levels. One nontreated and one DEM-treated group received cigarette smoke exposure; the other two groups received sham smoke exposure only. For the second protocol we used a lung explant system, and in addition to smoke- and sham smoke-exposed groups, we supplemented cellular GSH levels with GSH added to the medium. Cell proliferation was assessed by cell labeling with 5-bromo-2'-deoxyuridine (BrdU). We found that, in the intact rat, cigarette smoke induced cell proliferation in the airway epithelium and walls and in the vessel walls; GSH depletion induced or increased this proliferative effect in airway walls and in the vascular endothelium and walls. In the lung explants, cigarette smoke also induced cell proliferation in airway epithelium and airway and vessel walls, and GSH supplementation reduced proliferation in both control and smoke exposed airway epithelium. In the intact animals, smoke had no effect on tissue GSH either immediately or after 24 h. However, exposure of the explants to cigarette smoke exposure increased GSH after 24 h. We conclude that (1) cigarette smoke-induced cellular proliferation is a direct effect of cigarette smoke that probably does not require the presence of smoke-evoked inflammatory cells, and (2) smoke-induced cell proliferation is related, at least partially, to the level of GSH and, by implication, to the balance between oxidants and antioxidants in the tissues.     

Evaluation of the potential effects of ingredients added to cigarettes. Part 4: subchronic inhalation toxicity.

Mainstream smoke from blended research cigarettes with (test) and without (control) the addition of ingredients to the tobacco was assayed for inhalation toxicity. In total, 333 ingredients commonly used in cigarette manufacturing were assigned to three different groups. Each group of ingredients was introduced at a low and a high level to the test cigarettes. Male and female Sprague-Dawley rats were exposed nose-only either to fresh air (sham) or diluted mainstream smoke from the test, the control, or the Reference Cigarette 1R4F at a concentration of 150 microg total particulate matter/l for 90 days, 6h/day, 7 days/week. A 42-day post-inhalation period was included to evaluate reversibility of possible findings. There were no remarkable differences in in-life observations or gross pathology between test and control groups. An increase in activity of liver enzymes, known to be due to the high smoke dose, revealed no toxicologically relevant differences between the test and control groups. No toxicological differences were seen between the test and control groups for smoke-related hematological changes, such as a decrease in total leukocyte count. The basic smoke-related histopathological effects, which were more pronounced in the upper respiratory tract than in the lower respiratory tract, were hyperplasia and squamous metaplasia of the respiratory epithelium, squamous metaplasia and atrophy of the olfactory epithelium, and accumulation of pigmented alveolar macrophages. There were no relevant qualitative or quantitative differences in findings in the respiratory tract of the rats exposed to the smoke from the control and test cigarettes. The data indicate that the addition of these 333 commonly used ingredients, added to cigarettes in three groups, did not increase the inhalation toxicity of the smoke, even at the exaggerated levels used.     

Cigarette smoke exposure does not prevent cadmium-induced alterations in rat lungs.

Cigarette smoke has been demonstrated to suppress the biosynthesis of connective tissue in the lung. To further characterize this suppressant effect, we studied the ability of cigarette smoke to prevent or ameliorate cadmium-induced alterations in rat lungs in vivo. The effects of beta-aminopropionitrile (beta APN), an agent that inhibits the cross-linking of elastin, also were studied. Eighty-eight young female Long-Evans rats were randomly divided into seven groups as follows: control, cigarette smoke, sham smoke, beta APN, cadmium, cadmium + cigarette smoke, and cadmium + beta APN. Each animal in the cigarette smoke group was exposed to mainstream smoke generated from University of Kentucky 2R1 reference cigarettes (10 puffs daily for 12 wk). Sham-treated animals received room air in place of cigarette smoke. beta APN (0.5 g/kg) was injected intraperitoneally twice weekly. In cadmium-treated groups, each rat received intermittently three intratracheal instillations of cadmium chloride (0.15 mumol/kg) over a 5-d period. For the cadmium + cigarette smoke group, smoke exposure began 3 d after the first cadmium instillation and was continued for 12 wk. The beta APN administration began 5 d before cadmium instillation and also was continued for 12 wk. After these treatments, pulmonary function and lung morphometry were examined. Neither cigarette smoke, sham smoke, nor beta APN produced significant changes in lung function or morphometry. Cadmium caused significant decreases in total lung capacity, dynamic and static compliance, and carbon monoxide diffusing capacity, as well as significant increases in lung weight and alveolar wall thickness. In addition, the quasistatic deflation pressure-volume curve showed a rightward shift whereas the mean linear intercept of the alveoli did not change significantly. Efforts to prevent or ameliorate the changes through exposure to cigarette smoke or administration of beta APN were unsuccessful. It is concluded that interventions designed to inhibit the biosynthesis of lung connective tissue do not perforce inhibit the development of cadmium-induced pulmonary changes in the rat.     

In utero and lactation exposure of rats to 1R4F reference cigarette mainstream smoke: effect on prenatal and postnatal development.

Childhood cognitive and behavioral deficits have been reported in children born to mothers who smoked during pregnancy (Institute of Medicine, 2001). To investigate these potential responses in an animal model, reproductive and neurotoxicity evaluations based on the U.S. FDA guidelines were used to examine the offspring of male and female Sprague-Dawley rats exposed 2 h/day, 7 days/week by nose-only inhalation to whole mainstream smoke total particulate matter (TPM). Concentrations of 150, 300, or 600 mg/m(3) were used (males: 4 weeks prior to and during mating; and females: 2 weeks prior to mating, during mating, and through weaning at postnatal day 21). Sham air controls receiving filtered air and cage controls were also maintained. F(1) rats were weighed, identified by gender, examined for clinical signs of toxicity, and evaluated for neurobehavioral effects through postnatal day 65. Parental exposure was evidenced by smoke concentration-related increases in blood carboxyhemoglobin, nicotine, and cotinine and by characteristic cigarette smoke-related rodent respiratory tract histopathology. Also, nicotine and cotinine were found in F(1) blood through the lactation period. Maternal toxicity occurred at concentrations of 300 and 600 mg TPM/m(3), where total body weight gain during gestation was significantly (p < or = 0.05) decreased compared to sham controls. While smoke concentration-related decreases in F(1) birth weight and growth were evident (600 mg TPM/m(3), significantly different from sham at all time points), no adverse effects on developmental landmarks, including age at vaginal patency or preputial separation, motor activity, acoustic startle response or learning, and memory, were observed in the F(1) generation. This study confirmed that maternal exposure to high levels of mainstream cigarette smoke during gestation and lactation reduces birth weight and retards growth in the rat neonate; however, the developmental and neurobehavioral testing methodologies employed did not appear to be sensitive for an evaluation of neonatal behavioral effects following parental smoke exposure.     

Pathological alterations in Syrian golden hamster lungs after passive exposure to cigarette smoke

The effects of 2 types of research cigarettes, differing in their total smoke delivery and condensate, were examined as to their histopathological effects on Syrian golden hamster lungs. The animals were passively exposed to the total smoke of the cigarettes once a day, 5 days/week for 1 year. Experimental and control animals were killed one day after termination of exposure. Varying effects on the macrophages of pulmonary alveolar tissue were observed. Infiltration of lung tissue by “Brown cells” was a common pathological alteration. Qualitative and quantitative differences existed between the two cigarette groups with respect to the occurrence of such “Brown cell” clumps. The response of the lung tissue to smoke exposure would appear to be dependent upon the amount of mainstream total particulate matter (TPM), the amount of condensate, the time exposed and the number of cigarettes.     

Cigarette smoke causes inhibition of the immune response to intratracheally administered antigens

Chronic inhalation of cigarette smoke in rats preferentially inhibited the plaque-forming cell (PFC) response of lung-associated lymph nodes (LALN) to sheep red blood cells (SRBC), compared to anatomically distant lymph nodes. Inhibition of the antibody response in LALN of smoke-exposed animals was first detected at 21 weeks of smoke inhalation and was well established by the 27th week of smoke exposure. After prolonged exposure (greater than 34 weeks) to cigarette smoke, similar smoke-induced changes in PFC response took place in other lymphoid tissues as well. Cigarette smoke affected the response of LALN cells to a T cell-dependent antigen (SRBC). Exposure to cigarette smoke, however, did not alter the relative percentages of W3/13-positive (T cells) or Ig-positive (B cells) cells, nor did it alter the relative percentages of T cell subsets as scored by their surface phenotypes, i.e., T helper (W3/25+) or T suppressor/cytotoxic (OX-8+) cells. The percentage of phagocytic cells and the accessory cell functions of macrophages remained comparable between sham and smoke-exposed animals. Exposure to cigarette smoke did not significantly alter the response of LALN cells to T cell mitogens (concanavalin A and phytohemagglutinin). However, response to a T cell-independent antigen trinitrophenyl Brucella abortus was also significantly reduced. These results show that cigarette exposure in the rat results in a decreased antibody response and this exposure to cigarette smoke may primarily affect the B cell function.     

Evidence for cigarette smoke-induced oxidative stress in the rat pancreas

Background/aims: Recent findings with a rodent model of cigarette smoke inhalation revealed a causal relationship between chronic exposure to cigarette smoke and the development of pancreatitis. The present study was conducted to ascertain whether cigarette smoke induces oxidative stress in the rat pancreas concurrently with inflammation.

Methodology: Rats (six per treatment group) were treated for 0, 3, 6, 9, or 12 weeks with cigarette smoke (0.7?mg/L). Pancreatic tissues were examined for histological and pathological alterations and serum for changes in interleukin-6 concentration. Pancreatic expression and localization of α-smooth muscle actin, transforming growth factor-β1, and collagen-1 were determined as measures of progressive inflammation/fibrosis. Pancreatic superoxide dismutase and glutathione peroxidase activities and malondialdehyde content were measured as indices of oxidative stress.

Results: Inflammatory cell infiltration and ductal hyperplasia were detected in pancreata after 12 weeks of treatment with cigarette smoke. The serum interleukin-6 concentration increased significantly and pancreatic glutathione peroxidase activity declined significantly after 12 weeks of treatment. No other significant changes were observed.

Conclusions: Pancreata of rats exposed chronically to cigarette smoke exhibit inflammation concurrently with suppression of glutathione peroxidase activity. These observations favor a role for oxidative stress in the induction of pancreatitis associated with chronic cigarette smoke inhalation.