Biomedical subjects

R E Chapin

Publications and source records attributed to R E Chapin.

At least 73 records · Page 4Linked to original sources

PubMed1990

Calcium channel blockers protect against ethylene glycol monomethyl ether (2-methoxyethanol)-induced testicular toxicity.

Disruption of normal calcium homeostasis has been implicated in the development of cell injury by certain chemicals. Furthermore, calcium channel blockers, which may prevent such a disruption, were shown to protect against this type of cellular damage in some excitable and nonexcitable tissues. Therefore, the present work was designed to address the role of calcium in the pachytene cell death caused by ethylene glycol monomethyl ether (EGME) by investigating the effect of the calcium channel blockers, verapamil and diltiazem, on the pathogenesis of such lesions. Male F344 rats were treated with a single gavage dose of 200 or 300 mg EGME/kg. Other groups of rats were treated with the same doses of EGME in combination with one, two, three, or four doses of verapamil or diltiazem. Twenty-four hours after administration of EGME, the animals were sacrificed, and the left testis and epididymis were excised, fixed in Bouin's solution, embedded in paraffin, sectioned, and stained with PAS-H. The sections were evaluated "blind" and scored for the number of lesioned stage XIV tubules. At 200 mg/kg, EGME produced a moderately severe lesion as characterized by pachytene spermatocyte cell death in stage XIV semniferous tubules. Verapamil was protective against this lesion with the protection being directly proportional to the number of verapamil doses administered and was maximum in rats treated with three doses. At 300 mg/kg, EGME caused a severe lesion in the testis, and verapamil was not as effective in protecting against this lesion as against the low dose of EGME. In contrast, diltiazem was not as effective as verapamil at either dose of EGME. These studies show, for the first time, that verapamil protects rats against EGME-induced testicular toxicity.

Animals↗

PubMed1990

The interaction of Sertoli and Leydig cells in the testicular toxicity of tri-o-cresyl phosphate.

Previous studies have shown that after dosing with tri-o-cresyl phosphate (TOCP), the testis contains more active intermediate (saligenin cyclic-o-tolyl phosphate; SCOTP) than do other organs or blood. SCOTP is produced by a cytochrome P450-dependent reaction, and the Sertoli cells, although containing little P450, are the testicular cells that show the first signs of damage after TOCP administration. The present studies evaluated (i) whether testicular Leydig cell production of SCOTP might explain the elevated testicular concentration of SCOTP, (ii) if this production affected testosterone secretion, and (iii) if Sertoli cells cocultured over TOCP-exposed Leydig cells would show effects similar to those found after SCOTP exposure of Sertoli cells in vitro, indicating a cell interaction. Previous data showed that a target enzyme for SCOTP in Sertoli cells, nonspecific esterase (NSE), was inhibited by exposure in vitro to SCOTP, but not to TOCP. In the present experiments, HPLC analysis identified SCOTP in media from Leydig cells cultured with radiolabeled TOCP, demonstrating activation. TOCP addition to Leydig cells decreased testosterone output after stimulation with hCG, an effect that was replicated by subsequent in vivo experiments. Addition of various intermediates in the testosterone biosynthesis pathway indicated that both mitochondrial- and microsomal-based steps in the pathway were affected. Collectively, these data indicate that Leydig cells can activate TOCP. To model whether this activation might affect Sertoli cells in vivo, Sertoli cells were plated in culture-well inserts suspended above (cocultured with) isolated Leydig cells in the presence of TOCP. Sertoli NSE activity was diminished, while remaining unchanged when cultured in the presence of TOCP but without Leydig cells, or over Leydig cells alone. These results show that the Leydig cells in the testis are capable of activating TOCP to SCOTP, and that this can produce effects in Sertoli cells. This in situ activation of TOCP to SCOTP may help explain why the testis contains high concentrations of SCOTP after in vivo dosing with TOCP, and why the testis is a target organ for TOCP toxicity.

Androstenedione↗

PubMed1990

Semen analysis and fertility assessment in rabbits: statistical power and design considerations for toxicology studies.

Semen analysis is commonly used in evaluating human response to reproductive toxicants. Serial semen samples can be collected from rabbits and fertility assessed by artificial insemination, hence this species is potentially well suited for male reproductive toxicity studies that might be extrapolated to humans. However, the size and cost of rabbits often restricts the number of animals used, reducing the sensitivity of such studies. Therefore, it was of interest to optimize study design for semen analysis and fertility assessment in rabbits. Semen samples were collected weekly from sexually mature New Zealand white rabbits and a range of parameters was analyzed (Semen--pH, volume, osmolality; Sperm--number and concentration, morphology, viability, percentage motility, motion characteristics; Seminal plasma--fructose, citric acid, carnitine and protein concentrations, acid phosphatase activity). Male fertility was assessed by inseminating female rabbits with the minimum number of motile sperm required for normal fertility, determined to be one million. The within- and between-buck variabilities were determined for all parameters and used to calculate the statistical power of different study designs. The variability of sperm number and concentration was decreased when measured in four ejaculates collected within a short period of time rather than in a single ejaculate; this was not true of other endpoints measured. In addition, use of preexposure observations further increased the statistical power for all of the parameters. These data can be used to determine the optimum design for studies of male reproductive toxicity using rabbits, with particular regard to cost and the number of animals used.

Acid Phosphatase↗

PubMed1989

Mono-2-ethylhexyl phthalate, a metabolite of di-(2-ethylhexyl) phthalate, causally linked to testicular atrophy in rats.

Acute testicular atrophy results when appropriate dosages of di-(2-ethylhexyl) phthalate (DEHP) or its hydrolysis product mono-2-ethylhexyl phthalate (MEHP) are given to male rats. Events thought to be involved in this pathological effect also occur in cultures of testicular cells in vitro, but require MEHP rather than DEHP. Primary cultures of hepatocytes, Sertoli cells, and Leydig cells were incubated with 14C-labeled MEHP [8 microM] for up to 24 hr. No significant reduction in viability was produced under these conditions. In contrast to the hepatocytes, which extensively metabolized MEHP to a variety of products in 1 hr, the testicular cell cultures were apparently unable to metabolize MEHP (beyond a slight hydrolysis to phthalic acid by Sertoli cells) in 18-24 hr. MEHP was efficiently taken up by hepatocytes, but much less so by testicular cells. These results, combined with related observations from the literature, support the hypothesis that MEHP itself is the metabolite of DEHP responsible for testicular atrophy in rats.

Animals↗

PubMed1989

Inhibition of FSH-stimulated cAMP accumulation by mono(2-ethylhexyl) phthalate in primary rat Sertoli cell cultures.

High doses of phthalate esters in vivo cause testicular lesions. One initial target for these effects is the sustentacular Sertoli cell. Sertoli cells are unique in that they have surface membrane receptors for follicle-stimulating hormone (FSH), which couple to adenylate cyclase. As a means of investigating why phthalates appear specific for Sertoli cells, we evaluated possible effects of an active monoester [mono(2-ethylhexyl) phthalate, MEHP] on the ability of FSH to elevate intracellular levels of cAMP. MEHP reduced FSH-induced elevation of cAMP levels by approximately 40%. This inhibition by MEHP required a lag period of 6 hr and did not affect the dose of FSH which gave half-maximal stimulation, suggesting that MEHP does not compete with FSH for binding to its receptor. The MEHP inhibition was not affected by incubation in the presence of methylisobutylxanthine, a phosphodiesterase inhibitor, suggesting that MEHP does not stimulate the breakdown of cAMP. The MEHP-induced inhibition is specific for FSH; it does not affect the ability of forskolin, cholera toxin, isoproterenol, or prostaglandin E1 to stimulate Sertoli cell cAMP. Furthermore, inhibition occurs in the presence of pertussis toxin suggesting that MEHP action is independent of the inhibitory adenylate cyclase pathway. Further experiments will be necessary to define the specific mechanism of action of phthalates on Sertoli cells; however, these experiments do describe a specific site of action of MEHP in vitro which may be related to the in vivo testicular toxicity of phthalate esters.

Animals↗

PubMed1989

Reproductive toxicity of 2,2-bis(bromomethyl)-1,3-propanediol in a continuous breeding protocol in Swiss (CD-1) mice.

The effect of 2,2-bis(bromomethyl)-1,3-propanediol (BMP) on reproduction in Swiss CD-1 mice was evaluated by use of a continuous breeding protocol. BMP was administered in the feed at 0.1, 0.2, and 0.4% concentrations. Both male and female F0 mice (20 pairs per treatment group, 40 pairs of control animals) were dosed 7 days prior to and during a 98-day cohabitation period. Although the fertility index was unchanged in the high-dose group, BMP exposure significantly decreased the numbers of litters per pair, pups born alive per litter, and pup weight when adjusted for litter size. Crossover mating between treated and control F0 animals indicated a specific effect only on female reproductive capacity. At the highest dose, BMP caused a body weight decrease in the F0 animals of both sexes with no effect on relative organ weights. Sperm concentration, motility, morphology, and estrual cyclicity were unaffected by BMP exposure. Histopathology in the F0 animals revealed specific kidney lesions in both sexes; males were more sensitive than females. The last litter born in the 98-day breeding phase was reared to age 74 days and then mated to nonsiblings of the same treatment group. The effect of high-dose BMP exposure on F1 fertility, body and organ weights, sperm parameters, and estrual cyclicity was the same as that for the F0 animals, with the exception of the lack of renal lesions seen in the F1 females. These data show that BMP impaired fertility in female mice in both generations in the absence of an effect on reproductive organ weights and estrual cyclicity.

Animals↗

PubMed1989

Toxicology studies of a chemical mixture of 25 groundwater contaminants. III. Male reproduction study in B6C3F1 mice.

A mixture of chemicals has been developed that models contaminated groundwater around hazardous waste sites. We investigated the effects of this mixture on spermatogenesis in B6C3F1 mice. The animals consumed three different concentrations of this mixture for 90 days, after which time they were euthanatized. Although there was a concentration-related decrease in the amount of fluid consumed at the higher two concentrations, there were no differences in body weight among the groups. Similarly, there was no effect of mixture consumption upon the histology of liver, kidney, testis, epididymis, or seminal vesicles or upon the absolute organ weights of these organs. Kidney weight relative to body weight was increased in the high dose group. Epididymal sperm number and testicular spermatid count were not affected by treatment. These studies show that, at exposure levels that decrease fluid intake and increase adjusted kidney weight, there were no effects of this mixture on gametogenesis in male mice.

Animals↗

PubMed1989

Results and evaluations of 48 continuous breeding reproduction studies conducted in mice.

Results of 48 continuous breeding reproduction (RACB) studies are summarized and control data from these studies are used to determine the statistical sensitivity of each endpoint from different parts of these studies. Results of testing individual chemicals compared well with results of multigeneration studies reported in the literature. Continuous breeding studies were able to discriminate reproductive toxicants from nontoxicants, and provided valuable structure-activity information. When mice in continuous cohabitation produce multiple litters, the statistical sensitivity of fertility endpoints is quite high and is comparable to that associated with other sensitive indicators of reproductive function, such as testis weight and sperm parameter measures. The principal advantages of the RACB protocol in comparison to multigeneration studies are: (1) the increased sensitivity and statistical power, (2) the ability to monitor progression of toxicity and to detect subfertility, (3) use of a battery of endpoints including sperm measures, (4) the ability to determine the affected sex(es), and (5) slightly reduced testing time.

Animals↗

PubMed1989

Mechanistic approaches in the study of testicular toxicity: toxicants that affect the endocrine regulation of the testis.

This review will expand on the themes presented by Heindel and Treinen (1988). As a prelude to describing where selected compounds act on the endocrine regulation of the testis and the theories about their mechanisms, we will briefly review some of the central pathways that underlie this control. After reviewing some studies that define the site of action of lead on the reproductive system, we will discuss the "signature" lesion caused by androgen deficiency, and then move on to an evaluation of the effects of an antiandrogen (flutamide) on the male reproductive system. Finally, some consideration will be given to alterations in hepatic function which modify circulating levels of androgens.

Animals↗

PubMed1988

The effects of mono-(2-ethylhexyl)-phthalate on rat Sertoli cell-enriched primary cultures.

There is considerable evidence from in vivo studies that the Sertoli cell is an initial target cell for the actions of phthalates in the rodent testis. Because this metabolically active cell type plays a central role in spermatogenesis, we examined the effects of a toxic phthalate, mono-(2-ethylhexyl)-phthalate (MEHP), on the secretory and synthetic activities of primary testicular cell cultures isolated from 18-day-old rats. These cultures were 78-84% Sertoli cells. Exposure to MEHP decreased cellular ATP by ca. 20%, decreased production of radiolabeled 14CO2 from acetate, and decreased media levels of pyruvate, while it increased media levels of lactate and intracellular lipid. Protein synthesis, evaluated by radiolabeled leucine incorporation, was not affected by MEHP. Mitochondrial succinate dehydrogenase activity was decreased in the presence of MEHP. Michaelis-Menton kinetic analysis indicated this was a mixed inhibition. There was no apparent change in mitochondrial Rhodamine 123 uptake. These data are consistent with the concept that mitochondria are one target for the actions of MEHP in the Sertoli cell.

Adenosine Triphosphate↗

PubMed1988

Comparison of changes in serum androgen binding protein with germinal epithelial damage and infertility induced by di-n-pentyl phthalate.

Androgen binding protein (ABP), produced by Sertoli cells and released into seminiferous tubules and blood, was measured in the serum of di-n-pentyl phthalate (DPP)-treated rats as a potential index of germinal epithelial damage. A single oral dose of DPP (0, 0.25, 1.0, or 2.0 g/kg body wt in corn oil) was given to four groups of 110 Fischer 344 rats; 10 rats per group were killed weekly for 10 weeks. Effects of treatment on serum ABP were then compared with effects on other reproductive endpoints. Treatment did not produce any significant effect on body weight or weights of liver, kidney, prostate, and seminal vesicles. In high-dose rats, serum ABP values more than doubled 2 days after injection, remained significantly elevated for 3 weeks, then fell and remained significantly below control values from Week 4 through Week 10. Accordingly, 95% of the rats in this group showed greater than 50% of the seminiferous tubules degenerated, decreased epididymal sperm density, reduced testicular and epididymal weights, and up to 97% morphologically abnormal sperm. In medium-dose rats, serum ABP increased up to 48% during the first week, returned to control values by Week 2, and remained at control levels thereafter. Of these rats, 20% showed 20-50% degenerated tubules, decreased sperm density, reduced testicular and epididymal weights (which were not always statistically significant), and up to 23% abnormal sperm morphology. In low-dose rats, serum ABP levels were similar to those of controls, and the other parameters, except sperm density, also remained unchanged. To examine the effects of DPP on fertility, a second group of rats was exposed in an identical manner [gavaged once with DPP in corn oil (0, 0.25, 1.0, and 2.0 g/kg body wt)], then mated to untreated females at 3, 6, and 10 weeks postexposure. DPP at 2 (but not 1.0 or 0.25) g/kg caused a significant reduction in pregnancies and live pups and a significant increase in preimplantation loss. Histopathology of the testis in the first experiment suggested a very slow recovery. Therefore, controls and high-dose rats in the mating trial were killed 14, 18, and 30 weeks after dosing and the germinal epithelium was evaluated histologically. All high-dose animals showed testicular lesions typical of phthalate ester exposure and the epithelium did not recover within 30 weeks.(ABSTRACT TRUNCATED AT 400 WORDS)

Androgen-Binding Protein↗

PubMed1988

Reproductive toxicity of tricresyl phosphate in a continuous breeding protocol in Swiss (CD-1) mice.

The effects of a mixture of tricresyl phosphate isomers on reproductive performance in Swiss (CD-1) mice were evaluated using a continuous breeding protocol. Tricresyl phosphate (TCP) was mixed into the feed at 0, 0.05, 0.1, and 0.2% by weight. Although the fertility index was not changed in the animals consuming the high-concentration feed, the number of litters per pair decreased in a dose-related fashion, and the proportion of pups born alive, and their weight, was significantly decreased in the high-dose group. A crossover mating trial found impaired fertility in both males and females exposed to 0.2% TCP, with a greater effect in females. Histopathology of the F0 pairs revealed dose-related seminiferous tubule atrophy, and decreased testis and epididymal weights in the high-dose males, while the female reproductive tract showed no histopathologic changes. There were dose-related changes in the adrenals of both sexes, and body weight was depressed in both sexes at the highest concentration. The last litter born in the 98-day breeding phase was reared to age 74 days and then mated within the control and two of the treatment groups (0.0, 0.05, and 0.1% TCP; there were too few offspring in the 0.2% group). There was a decrease in the fertility index in the 0.1% TCP group, and a decreased proportion of liveborn and number of liveborn pups per litter. In the F1 males at necropsy, sperm concentration and morphology were normal at termination, although motility was decreased in both the 0.05% and the 0.1% groups compared to controls. These data show that TCP impaired fertility in both sexes of mice in the F0 generation and affected sperm motility at even the lowest dose in F1 males.

Adrenal Glands↗

PubMed1988

Testicular toxicity and reduced Sertoli cell numbers in neonatal rats by di(2-ethylhexyl)phthalate and the recovery of fertility as adults.

Neonatal and adult rats (1, 2, 3, 6, and 12 weeks of age) were given five daily oral doses of di(2-ethylhexyl) phthalate (DEHP) (0, 10, 100, 1000, 2000 mg/kg) and histological changes in the testes were examined 24 hr after the last dose. Relative testis weights were reduced at doses of 1000 mg/kg in 1, 2, 3, and 6-week-old but not in 12-week-old rats, while doses of 2000 mg/kg were fatal to suckling rats and caused decreased relative testis weight but not death in 6- and 12-week-old rats. In neonatal rats (1 week old), DEHP (1000 mg/kg) caused a 35% decrease in Sertoli cell numbers while 2- and 3-week-old rats showed losses of spermatocytes but not of Sertoli cells. The 6- and 12-week-old rats showed loss of both spermatids and spermatocytes at 1000 and/or 2000 mg/kg. Total testicular zinc concentrations were decreased in 12-week-old but not in suckling (3-week) or weaned (6-week) rats. The results support the hypothesis that the Sertoli cell is the primary testicular target of phthalate ester toxicity since effects were observed at an age when only Sertoli cells were present. Fertility was assessed in mating trials in adult male rats after neonatal exposure to DEHP on Days 6-10. Although Sertoli cell number was reduced 24 hr after the last dose, the numbers were normal at 6 and 13 weeks of age. However, at 6 weeks there was a dose-related decrease in maturation of the spermatids in the tubules. There were no consistent changes in fertility, implantation rate, or numbers of live fetuses in untreated females mated with the DEHP-treated males. However, there were decreases in testis weight and testicular spermatid numbers at 13 and 19 weeks but not at 11, 12, 16, or 23 weeks of age. Therefore, a loss of Sertoli cells due to DEHP exposure neonatally did not affect the fertility of the rats as adults, but may have caused subtle effects on sperm production.

Age Factors↗

PubMed1987

Reproductive tract lesions resulting from subchronic administration (63 days) of tri-o-cresyl phosphate in male rats.

An initial dose-range pilot study where animals were gavaged with between 100 and 1600 mg tri-o-cresyl phosphate (TOCP)/kg/day for 14 days resulted in decreased epididymal sperm density and disruption of the seminiferous epithelium in 100% of treated animals. A subchronic 63-day study (reflecting the 49-day length of the rat seminiferous epithelium cycle plus the 14-day transit time of spermatids through the epididymis was initiated. Dose-dependent (10 to 100 mg TOCP/kg/day) decreases in cauda epididymal sperm motility and density, testicular enzyme activities, and alterations in sperm morphology were observed. Concurrent pair-fed controls (matched to the highest dose group, 100 mg TOCP/kg/day) indicated that weight loss resulting from TOCP administration had minimal contributory effects to the testicular toxicity seen. Plasma alpha-tocopherol acetate (vitamin E) and testosterone concentrations were unaffected. Tri-p-cresyl phosphate (TPCP), the nonneurotoxic structural analog of TOCP, produced no toxic effects, demonstrating the necessity of the ortho-cresol moiety for induction of damage. A minimum effective (threshold) dose for observable testicular toxicity was determined to be 10-25 mg TOCP/kg in this study. These data suggest that TOCP interferes with spermatogenic processes and sperm motility directly and not via an androgenic mechanism or decreased vitamin E availability.

Animals↗

PubMed1987

Time course of the tri-o-cresyl phosphate-induced testicular lesion in F-344 rats: enzymatic, hormonal, and sperm parameter studies.

Tri-o-cresyl phosphate (TOCP), a known neurotoxic compound, causes testicular toxicity in both leghorn roosters and Fischer 344 rats. The present study was initiated to follow the onset of the testicular lesion through possible changes in sperm numbers and production, serum hormones, and various enzyme activities. Rats were administered TOCP daily (150 mg/kg) for periods of 3, 7, 10, 14, or 21 days. Vehicle-treated animals served as controls. Sperm motility and sperm number per milligram cauda epididymis were both lower in treated animals by Day 10. Testicular weight to body weight ratio was significantly decreased only in the longest treatment duration animals (21 days). Testicular neurotoxic esterase and nonspecific esterase activities were also inhibited, while beta-glucuronidase activity was not affected. Luteinizing and follicle-stimulating hormone levels were normal, as were both serum and interstitial fluid testosterone concentrations. Sertoli cell fluid secretion, as measured by testis weight increase after efferent duct ligation, showed no significant changes. Other organs (spleen, liver, kidney, pancreas, small intestine, adrenal and pituitary glands) had no overt signs of pathology as observed by light microscopy in animals treated for 21 days. A separate group of animals was treated for 21 days and subsequently examined after 98 days of observation (two cycles of the rat seminiferous epithelium). No recovery of spermatogenesis was seen, indicating that the toxicity was irreversible at the dose used. The effects noted in these studies further define the testicular lesion produced by TOCP and show that 150 mg/kg/day for 21 days produced irreversible testicular toxicity.

Animals↗

PubMed1987

Reproductive effects of four phthalic acid esters in the mouse.

These studies compared the reproductive toxicity of four phthalates by a continuous breeding protocol. Mice were given diets with diethyl phthalate (DEP) (0.0, 0.25, 1.25, or 2.5%), di-n-butyl phthalate (DBP) (0.0, 0.03, 0.3, or 1.0%), di-n-hexyl phthalate (DHP) (0.0, 0.3, 0.6, or 1.2%), or di(2-ethylhexyl) phthalate (DEHP) (0.0, 0.01, 0.1, or 0.3%). Both male and female CD-1 mice were dosed for 7 days prior to and during a 98-day cohabitation period. Reproductive function was evaluated during the cohabitation period by measuring the numbers of litters per pair and of live pups per litter, pup weight, and offspring survival. There was no apparent effect on reproductive function in the animals exposed to DEP, despite significant effects on body weight gain and liver weight. DBP exposure resulted in a reduction in the numbers of litters per pair and of live pups per litter and in the proportion of pups born alive at the 1.0% amount, but not at lower dose levels. A crossover mating trial demonstrated that female mice, but not males, were affected by DBP, as shown by significant decreases in the percentage of fertile pairs, the number of live pups per litter, the proportion of pups born alive, and live pup weight. DHP in the diet resulted in dose-related adverse effects on the numbers of litters per pair and of live pups per litter and proportion of pups born alive at 0.3, 0.6, and 1.2% DHP in the diet. A crossover mating study demonstrated that both sexes were affected. DEHP (at 0.1 and 0.3%) caused dose-dependent decreases in fertility and in the number and the proportion of pups born alive. A crossover mating trial showed that both sexes were affected by exposure to DEHP. These data demonstrate the ability of the continuous breeding protocol to discriminate the qualitative and quantitative reproductive effects of the more and less active congeners as well as the large differences in reproductive toxicity attributable to subtle changes in the alkyl substitution of phthalate esters.

Animals↗

PubMed1987

Testicular toxicity following oral administration of tri-o-cresyl phosphate (TOCP) in roosters.

Tri-o-cresyl phosphate (TOCP) is a neurotoxic organophosphorus compound that induces a characteristic central-peripheral distal axonopathy and Wallerian-type degeneration, 6-14 days after exposure. This organophosphorus compound-induced delayed neurotoxicity (OPIDN) has been extensively studied in the chicken, the standard test model. Reports of neurotoxic agents causing adverse effects on the male reproductive system initiated the present study which was designed to examine the effects of TOCP on the rooster. Previous work from this laboratory has demonstrated 100 mg TOCP/kg/day to be an OPIDN-inducing dose with minimal mortality in roosters. This dose level was administered to adult leghorn roosters (p.o., n = 10) for 18 consecutive days. By days 7-10 of the study, TOCP-treated birds exhibited limb paralysis characteristic of OPIDN. Analysis at termination revealed significant inhibition of neurotoxic esterase activity (NTE) in both brain and testis. There was also a slight decrease in brain acetylcholinesterase (AChe) activity. Sperm motility was shown to be greatly decreased. In addition, sections of formalin-fixed, methacrylate-embedded testes from TOCP-treated birds showed vacuolation of, and disorganization in the seminiferous epithelium. The marginal body weight decreases (17%) in treated animals were not considered to contribute to the testicular toxicity induced by TOCP. Parathion (O,O-diethyl-O-4-nitrophenyl phosphorothioate, 0.1 mg/kg/day, p.o., n = 3) was used as a positive control for AChE inhibition and a negative control for inducing OPIDN. Roosters treated continuously with parathion showed a decrease in brain AChE activity, but no changes in NTE, testicular histology, or limb function. These studies demonstrate the testicular toxicity of TOCP in roosters and suggest that this effect is not related to the chemical's anticholinergic action.

Animals↗

PubMed1987

Quantitation of silica-induced type II cell hyperplasia by using alkaline phosphatase histochemistry in glycol methacrylate embedded lung.

A light microscopic technique based on alkaline phosphatase histochemistry was developed to specifically quantitate Type II cells in the intact rat lung. Lungs were fixed in 4% neutral-buffered formalin containing 0.25 M sucrose and embedded in glycol methacrylate. Two micron thick sections were mounted on glass microscope slides. Alkaline phosphatase activity was localized by using naphthol AS-BI phosphate as substrate in 0.125 M 2-amino-2-methyl-1-propanol buffer containing 0.625 mM MgCl2 (pH 8.9). Sections were counterstained with Harris hematoxylin. Type II cells were the only cell type in the alveolar region containing alkaline phosphatase activity, an observation that was confirmed by using electron microscopic histochemistry. By combining the alkaline phosphatase staining technique with standard morphometric procedures, the proliferative response to a single intratracheal dose of 10 mg silica was followed as a function of time. Type II cells were significantly increased at all time points examined. Twenty eight days following silica, Type II cells had increased to (252 +/- 16) X 10(6) cells per set of lungs compared to a control value of (141 +/- 32) X 16(6) cells. The method presented is a simple and rapid technique for examining Type II cell population kinetics.

Alkaline Phosphatase↗