Protein-bound pyrroles in rat hair following subchronic intraperitoneal injections of 2,5-hexanedione

Studies were initiated to ascertain whether body hair could be used to develop a biological marker for chronic exposure to industrial neurotoxicants that yield the metabolite 2,5-hexanedione (2,5-HD), that is, n-hexane and methyl n-butyl ketone. Rats were injected daily with a 50 mg/kg ip dose of 2,5-HD for 45 d. At intervals, body hair and individual vibrissae were removed (under general anesthesia) and tested for the presence of pyrrole substances with p-N,N-dimethylaminobenzaldehyde (DMAB, Ehrlich's reagent). Vibrissae and body hair were stained a reddish color that was distinctly different from that observed with the hair taken from control animals. Solubilized body hair protein from the treated animals gave a positive Ehrlich's test, while that from control animals was negative. Spectral analysis of the DMAB-treated hair from experimental animals disclosed a maximum absorbance at 530 nm, which indicated the presence of pyrrole substituents. Serial analysis of individual nose hairs taken during 2,5-HD administration showed a progression with time of the region staining positively for pyrroles, thus indicating that the process can proceed in growing hair. These findings suggest the potential utility of hair as an indicator for chronic exposure to this class of industrial chemicals possessing neurotoxicity potential. This could complement urinary analysis, which is now used to confirm recent exposure.

Neurotoxicity of glycidamide, an acrylamide metabolite, following intraperitoneal injections in rats

Acrylamide (2-propenamide) monomer produces central-peripheral distal axonopathy in humans and some animal species. Its neurotoxicity is characterized by abnormal sensation, decreased motor strength, and ataxia. Acrylamide forms adducts with glutathione, proteins, and DNA. Recent studies demonstrated that acrylamide is metabolized to its epoxide, glycidamide (2,3-epoxy-1-propanamide). We studied the neurotoxicity potential of glycidamide in male Sprague-Dawley rats. Animals (groups of 6) were injected ip daily with either aqueous acrylamide or glycidamide at an acrylamide-equivalent dose of 50 mg/kg (0.70 mmol/kg). Both treatments resulted initially in the rats circling, which was followed by the onset of ataxia at 7-9 d and hindlimb paralysis at 12-14 d. Treated animals showed muscle wasting. At termination, acrylamide- and glycidamide-treated rats weighed 105% and 86% of initial weight, respectively, compared to 145% for controls. Animals were anesthetized and perfused with 10% neutral phosphate-buffered formalin 12 or 14 d after beginning of treatment. Both treatment groups exhibited similar neuropathologic changes in the central and peripheral nervous systems. More severe lesions were produced by glycidamide. A marked increase in the number of affected Purkinje cells in the cerebellum, which exhibited changes ranging from pyknosis to cell death, were present. The brainstem exhibited axonal degeneration with chromatolytic necrosis in midbrain medial and lateral reticular nuclei. The spinal cord was characterized by spongy form changes with vacuoles of different sizes in various levels. These results suggest that glycidamide is an active neurotoxic metabolite of acrylamide.

The effect of evening bright light in delaying the circadian rhythms and lengthening the sleep of early morning awakening insomniacs

Past studies have predicted that early morning awakening insomnia is associated with advanced or early circadian rhythms. Because bright light stimulation in the evening can delay the phase of circadian rhythms, we tested its effects on nine (4 females, 5 males) early morning awakening insomniacs. Their sleep was evaluated with wrist actigraphy and their temperature and melatonin circadian rhythms were measured in constant routine procedures. In the initial evaluation, the temperature rhythm phase positions of these insomniacs did appear to be earlier than normal. The subjects were then exposed to bright light stimulation (2,500 lux) from 2000 to 2400 hours on two consecutive evenings. Following the evening bright light treatment, temperature rhythm phase markers were delayed 2-4 hours and melatonin phase markers were delayed 1-2 hours. Sleep onset times were not changed but the mean final wake-up time was delayed from 0459 hours to 0611 hours, resulting in a mean increase of total sleep time of > 1 hour. This pilot study suggests that evening bright light stimulation may be an effective nondrug treatment for early morning awakening insomnia.

Phase resetting of the human circadian pacemaker with use of a single pulse of bright light

Since the initial studies reporting that light can alter the phase position of the human circadian system, there has been increasing interest in the use of bright light as a tool for manipulating the phase position of the circadian pacemaker. Exposure protocols typically require subjects to receive 2-5 h of exposure over several circadian cycles. As a consequence, bright light treatment can involve a considerable time investment. However, recent studies indicate that a single pulse of bright light can produce significant phase shifts in the circadian pacemaker. If a single pulse of bright light can produce significant phase-shifting effects, multiple-pulse designs may be unnecessary. This study examined the phase-shifting effects of a single 4-h pulse of bright light (12,000 lux) in 14 male and one female subject aged between 19-45 years. With use of a "constant routine" to estimate circadian phase, a single 4-h pulse of light produced significant shifts in the phase of the core temperature rhythm. The timing of the exposure, relative to the core temperature rhythm, determined the degree and direction of the phase shift. Exposure immediately prior to habitual bedtime produced a mean phase delay in the core temperature of 2.39 h (SD = 1.37 h). In contrast, exposure immediately following habitual wake-up produced a mean phase advance of 1.49 h (SD = 2.06 h). In addition, the magnitude of the shift increased the closer the light pulse was to the individual's estimated endogenous core temperature minimum. There was, however, considerable interindividual variability in this relationship.(ABSTRACT TRUNCATED AT 250 WORDS)

The sleep-evoked decrease of body temperature

The circadian rhythm of deep body temperature consists of both an endogenous component and evoked components resulting from exogenous influences. Previous studies of the sleep-evoked effect have failed to control confounding influences, so that the effect of sleep per se has not been established. In the present study, eight good sleepers had their rectal temperatures recorded for 24 hours in each of two laboratory conditions employing a constant routine to control exogenous influences. Sleep was allowed at night in one condition. Following sleep onset, body temperature dropped more rapidly and remained lower than when wakefulness continued over the same time, resulting in a mean sleep-evoked decrease of 0.31 +/- 0.09 degree C. Fourier regression analysis showed a significant 24-hour (circadian) temperature rhythm, together with a 12-hour harmonic rhythm, in each condition. Circadian rhythm parameters were also altered by the sleep-evoked (or masking) effect, with the amplitude increased and the mean decreased when subjects slept at night in the constant routine. It was suggested that a constant routine methodology be used in studies of circadian rhythm differences and that Fourier regression be used in preference to simple cosine curve fitting to give a better approximation of the temperature rhythm.

The variability in circadian phase and amplitude estimates derived from sequential constant routines

Both the constant routine (CR) and the dim light melatonin onset have been suggested as reliable methods to determine circadian phase from a single circadian cycle. However, both techniques lack published studies quantifying the intercycle variability in their phase resolution. To address this question eight healthy male subjects participated in two CRs, 7 days apart. Circadian phase was determined using 3-min samples of core body temperature and two hourly urinary sulphatoxy melatonin excretion rates. Phase and amplitude were estimated using simple (24 h) and complex (24 + 12 h) cosinor models of temperature data and the onset, offset, and a distance-weighted-least-squares (DWLS) fitted acrophase for the melatonin metabolite. The variability in phase estimates was measured using the mean absolute difference between successive CRs. Using the simple 24 h model of temperature data, the mean absolute phase difference was 51 min (SD = 35 min). Using the complex model, the mean absolute phase difference was 62 min (SD = 35 min). Using the DWLS fitted acrophase for the melatonin metabolite, the mean absolute phase difference between CR1 and CR2 was 40 min (SD = 26 min). The results indicate that for CRs a week apart, the mean absolute difference in an individual's phase estimate can vary by 40-60 min depending on the choice of dependent measure and analytic technique. In contrast to the intraindividual variability, the group results showed considerably less variability. The mean algebraic difference between CRs, using temperature- or melatonin-derived estimates, was less than 5 min, and well within the range of normal measurement error.

Proton magnetic resonance studies of the aggregation of taurine-conjugated bile salts

The concentration dependence of the 500 MHz 1H-NMR spectra of taurocholate, taurochenodeoxycholate, taurodeoxycholate, and the monosulfate esters of taurochenodeoxycholate has been examined at 0.154 M NaCl in D2O. The resonances of the C18, C19, and C21 methyl groups and the C23 methylene group are differentially broadened with respect to the C25 and C26 methylene and C7 (or C12) methine groups with increasing bile salt concentration for each of the bile salts studied. These data confirm hydrophobic association and indicate that the side chain contributes to the hydrophobic surface of the bile salt. The chemical shift difference of the anisochronous C23 methylene protons is different in monomer and aggregate form. The C25 methylene protons are isochronous in monomeric form but anisochronous in aggregate form. The concentration dependence of the observed chemical shifts has been analyzed to estimate the critical concentration associated with the onset of these changes. The conformer population about the C22-C23 bond changes before the anisochronicity of the C25 methylene protons develops. This indicates that the C23 methylene group is affected by the initial stages of self-association, whereas specific motional constraints about the N-C25 bond in the taurine moiety are only induced in large primary micelles. The difference in the chemical shift of the C25 methylene protons depends on the structure of the bile salt. The relative magnitude of the shift differences is not altered by the presence of phosphatidylcholine. The data suggest that in primary micelles or mixed micelles the taurine moiety conforms to segregate the hydrophilic groups of the bile salt and effects greater van der Waals' contact between the hydrophobic surfaces.

Calcium binding by monosulfate esters of taurochenodeoxycholate

The effect of sulfate esterification of the 3 alpha- or 7 alpha-hydroxyl groups of taurochenodeoxycholate on calcium binding was studied at 0.154 M NaCl in the presence and absence of phosphatidylcholine using a calcium electrode. For comparison, similar studies were made with taurochenodeoxycholate, taurodeoxycholate, and taurocholate. No high affinity calcium binding was demonstrable for any of these bile salts in pre-micellar solutions. Taurine-conjugated bile salts have greater affinity for calcium when in a micellar form. At elevated bile salt concentrations, the calcium binding of unsulfated dihydroxy taurine conjugates was similar to that of the monosulfate esters of taurochenodeoxycholate. The presence of phosphatidylcholine decreased calcium binding of the unsulfated dihydroxy bile salts and slightly increased calcium binding by taurocholate. However, the addition of phosphatidylcholine to monosulfate esters of taurochenodeoxycholate results in large increments in calcium binding. The results indicate that increased calcium binding due to the presence of phosphatidylcholine in bile salt solutions depends, in part, on the hydrophilicity of the bile salt and that the interaction of monosulfate esters of taurochenodeoxycholate with phosphatidylcholine leads to the formation of a high affinity calcium binding site.

Sleep-onset insomniacs have delayed temperature rhythms

It was predicted from free running and ultradian cycle studies that sleep-onset insomniacs would have endogenous circadian rhythms that were phase delayed compared to good sleepers. Thirteen sleep-onset insomniacs and nine good sleepers were selected to differ only in their sleep-onset latencies as confirmed by polysomnography. their rectal temperatures were measured over a 26-h constant routine and analyzed with best-fit Fourier curves including 24-h fundamental and 12-h harmonic components. The temperature rhythm markers of the insomniacs' rhythms were approximately 2.5 h later than the respective phases of the good sleepers. The usual bedtimes of the insomniacs fell within the "wake maintenance zone" of their delayed temperature rhythm. The good sleepers had typical bedtimes several hours after their "wake maintenance zone" and closer to their body temperature minimum. It was suggested that manipulations to phase advance the insomniacs' rhythms would reduce their sleep-onset latencies. It was also predicted that early morning insomnia results from phase advanced circadian rhythms and that sleep maintenance insomnia results from an abnormal phase relationship between the 24-h temperature rhythm and 12-h sleep-alert rhythm.

The effect of sleep/wake state on nocturnal melatonin excretion

Twenty-four hour patterns of urinary 6-sulphatoxymelatonin excretion were monitored in eight healthy adult subjects in two bed rest constant routines, one with normal nocturnal sleep and one with continuous wakefulness. The implementation of dim light "constant routines" enabled the effect of the sleep wake/state on melatonin to be tested without the confounding effects of body activity and normal room lighting. In both conditions 6-sulphatoxymelatonin excretion was significantly higher during the nighttime hours (2200-1000) than during the daytime hours (1000-2200) producing averages of 80% and 78.5% of the total 24 hour output in the sleep and wakeful conditions, respectively. The large differences between subjects in nocturnal melatonin excretion (38 to 150 nmol) were highly consistent between the two conditions. There were no differences between the nocturnal wakeful and sleep conditions in total nighttime melatonin excretion nor in the nighttime percentage of the 24 hour total melatonin excretions. Therefore, the sleep/wake state alone had no effect on nocturnal melatonin excretion. On the other hand, a significant correlation between the nighttime melatonin percentage and sleep length suggested the need to investigate further the relation between the amplitude of the melatonin circadian rhythm and sleep length and quality.

Effects of monosulfate esters of taurochenodeoxycholate on bile flow and biliary lipids in hamsters

The effect of the 3 alpha- and 7 alpha-monosulfate esters of taurochenodeoxycholate on bile flow and biliary lipids was compared to the effect of unsulfated taurochenodeoxycholate. Test bile salts were infused directly into the portal circulation through a catheter introduced into the splenic pulp. Recovery of unsulfated and sulfated bile salts was complete; no biotransformation of any of the administered compounds was noted. Equivalent choleresis was noted in response to administration of each of the test bile salts. Of particular interest, the biliary cholesterol and phospholipid content was tightly linked to biliary bile salt monosulfates; the slope of the line describing the relationship between bile salts and lipids was similar to that for the unsulfated bile salt. The critical micellar concentration of the 3 alpha- and 7 alpha-monosulfate esters was 19 mM and 18 mM, respectively. Sulfation of taurochenodeoxycholate, therefore, does not impair its bile secretory function. Despite a higher critical micellar concentration, biliary lipid excretion with monosulfate esters is equivalent to that seen with unsulfated bile salt. The role of hydrophobic/hydrophilic balance in the promotion of biliary lipid excretion may need to be redefined.

Rat hepatic bile acid sulfotransferase: enzyme response to androgens and estrogens

Rat liver bile sulfotransferase activity can be divided into a fraction that reacts with a monoclonal antibody (PK1B) and another fraction that does not. This work was performed to analyze the known response of hepatic bile acid sulfotransferase activity to androgens and estrogens by determining the effect of treatment on the proportion of bile acid sulfotransferase activity that possessed the epitope for PK1B monoclonal antibody. Activity in treated animals was further characterized by high-performance liquid chromatography (HPLC) analysis following purification by PK1B-immunoadsorption chromatography. The results indicate that estrogens and androgens affect the subset of enzyme activity that has the PK1B epitope more than the population that does not. HPLC demonstrates that increases and decreases in activity that follow treatment with androgens and estrogens are mirrored by the proportion of the PK1B-reactive protein that exhibits a relative molecular weight (Mr) greater than 170,000. Radial immunodiffusion assays of hepatic supernatant using a polyclonal antibody raised against PK1B-reactive bile acid sulfotransferase show that changes in specific activity that follow treatment are the result of changes in enzyme protein concentration.

Rat hepatic bile acid sulfotransferase: identification of the catalytic polypeptide and evidence for polymeric forms in female rats

A monoclonal antibody, PK1B, directed against rat liver bile acid sulfotransferase was used for the purification and characterization of the enzyme. Incubation of rat liver supernatant with the antibody followed by immunoprecipitation with Staphylococcus aureus cells demonstrated that PK1B reacted with 90% of the enzymatic activity present in the liver supernatant from female rats and 40 to 50% of the activity in male liver preparations. Immunoadsorption chromatography with PK1B bound to Sepharose isolated active enzyme which was purified greater than 75-fold. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of this preparation in the presence of 2-mercaptoethanol demonstrated three polypeptides: Mr 29,500; 32,500, and 34,000. Western blot analysis indicated that PK1B recognized an epitope which was found only on the Mr 29,500 polypeptide. Two-dimensional gel electrophoresis associated the enzymatic activity with this Mr 29,500 band. High-pressure liquid chromatographic analysis of immunopurified enzyme defined three distinct, enzymatically active protein populations: I (Mr 400,000 to 170,000); II (Mr 130,000), and III (Mr 43,000). An Mr 29,500 polypeptide was the sole constituent of Peaks I and III and a major constituent of Peak II. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence and absence of 2-mercaptoethanol indicated that in Peak II, catalytically active Mr 29,500 protein is associated with the other two polypeptides by disulfide bonds. In contrast, Peak I consists of a polymer of Mr 29,500 polypeptide which is independent of disulfide interaction.

Positional requirements for anionic charge for ileal absorption of bile salt analogues

Previous structure-activity studies of the ileal bile salt cotransport system have suggested the idea that a coulombic interaction occurs between the negative charge of the bile salt and a cationic site on the carrier. Evidence included observations that modified bile salts with uncharged, cationic, or zwitterionic side chains were poorly transported. They did interact with this system as evidenced by their abilities to inhibit transport. Another prerequisite for coulombic interaction is positional (side-chain) specificity for the anionic grouping. [14C]chenodeoxycholyl-N-ethanolamide-O-sulfate and the 3 alpha-sulfate ester of chenodeoxycholyl-N-ethanolamide were tested for their in vivo absorption from the jejunums and ileums of anesthetized guinea pigs. Active ileal transport was estimated by subtracting jejunal absorption (passive) from ileal absorption (active and passive). Translocation of the anionic SO4(-) radical from the side chain to the 3 alpha position of the steroid decreased active ileal absorption by 95%, demonstrating a positional requirement for the anionic group for optimal transport.

Prostatic cancer--II. Inhibitors of rat prostatic 4-ene-3-ketosteroid 5 alpha-reductase derived from 6-methylene-4-androsten-3-ones

The studied 6-methylene-4-androsten-3-ones proved to be significantly inferior to 6-methylene-4-pregnene-3,20-dione and its 17-acetoxy derivative described in Part 1 as inhibitors of 4-ene-3-ketosteroid 5 alpha-reductase [1] in vitro. Surprisingly, the 6-methylene derivative of testosterone was only weakly active until acetylated, when an effective inhibitor was obtained. Etherification of the hydroxyl-group, its replacement by a hydrocarbon chain, or introduction of a substituent at C17 or on the methylene group led to virtual loss of activity. 17 alpha-Chloro-6-methylene-4-androstene-3-one had ca 60-70% of the potency of progesterone, but was inactive as enzyme inhibitor in explants of rat prostate in tissue culture and in in vivo studies. 6-Methylenetestosterone acetate was weakly active as enzyme inhibitor in explants of human prostate in tissue culture and produced a histological picture closely resembling testosterone and differing from that of cyproterone acetate. In vivo in the rat it had 80% of the androgenic activity of testosterone propionate. The foregoing data have been used to define some structural characteristics necessary for enzyme inhibition and to draw some conclusions regarding the architecture of the androgen and progesterone receptors and of the enzyme active site.

Inhibitory effects of some steroidal 6-methylene derivatives on 5 alpha-reductase activity in human and rat prostate

Using a short-term organ culture assay, some 6-methylene derivatives of progesterone and testosterone have been evaluated for their effects on testosterone metabolism in rat and human prostatic tissues, and on DNA synthesis in explants from 7-day castrated rats. Comparative studies showed that the ability to inhibit 5 alpha-reductase activity was fairly specific with respect to structural requirements. Methylene substitution at the C6 position of the progesterone molecule was associated with high inhibitory activity. In explants prepared from human prostates, 6-methylene progesterone (II) had 70-85% (mean of 79% for 4 BPH tissues) of the potency of unmodified progesterone (I). Its 17 alpha-acetoxy-6-methylene analog (III), however, had only 32-73% (mean of 53% for 5 BPH specimens) of the activity of (I). The degrees of inhibition in rat and human prostatic tissues were similar. Inhibition of 5 alpha-reductase activity in cultured explants by 6-methylene progesterone (II) could not be reversed by change in media. The 6-methylene derivatives had little or no effect on DNA synthesis. Histological examination confirmed a lack of effect on basal cell proliferation. However, morphological alterations affecting epithelial cell height and secretory activity were clearly evident. These results indicate that, under our experimental conditions, the main effect of inhibition of 5 alpha-reductase activity in prostatic tissues by 6-methylene derivatives of progesterone is related to suppression of differentiated function.

Prostatic cancer. I. 6-Methylene-4-pregnen-3-ones as irreversible inhibitors of rat prostatic delta 4-3 ketosteroid 5 alpha-reductase

Some derivatives of 6-methylene-4-pregnen-3-one were studied as inhibitors of delta 4-3-ketosteroid 5 alpha-reductase. Maximum inhibitory activity was shown by 17-acetoxy-6-methylene-4-pregnene-3,20-dione (AMPD). Irreversible inactivation was observed following preincubation of the enzyme with NADPH and AMPD. This inactivation was found to occur only in the presence of NADPH. As such enzyme inactivation was not due to the formation of a more inhibitory metabolic product, or to the formation of superoxide via a cytochrome P-450/NADPH pathway, it seemed likely that the observed inactivation was derived from an irreversible combination of the enzyme with AMPD. That this was probably the case was established by kinetic studies which revealed a pattern compatible with a kcat type of mechanism.

Identification of the 3-sulfate isomer as the major product of enzymatic sulfation of chenodeoxycholate conjugates

Thin layer and high performance liquid chromatography identified the 3-monosulfate ester as the predominant product of in vitro enzymatic sulfation of glyco- and taurochenodeoxycholate by rat liver and kidney and hamster liver. The rate of synthesis of the 7-sulfate ester was less than 20% that of the 3-sulfate isomer; in vitro synthesis of the 3,7-disulfate was not definitely seen. Reaction of the enzymatic products with 7 alpha-hydroxysteroid dehydrogenase indicated a molar ratio of 7 alpha-hydroxyl function and SO4 which further supported the identification of the 3-sulfate isomer as the major product.

Short-term studies of taurocholate uptake by ileal brush border membrane vesicles: anion effects

Experiments allowing Na+-dependent short-term uptake measurements by ileal brush border vesicles were described. Glucose uptake was compared with taurocholate uptake in the presence of NaCl, NaSCN and Na2SO4. In contrast to the observation made with glucose, taurocholate transport was the same for the three electrolytes, indicating electroneutral taurocholate transport.