Evaluation of the sites of opioid influence on anterior pituitary hormone secretion using a quaternary opiate antagonist.

Studies were conducted to determine the effects of a potent narcotic antagonist, nalmefene methyliodide, which does not cross the blood-brain barrier (BBB), on the secretion of anterior pituitary hormones and on the anterior pituitary hormonal response to morphine sulfate. Since the localization of opiate receptor responses to inside or outside the BBB depended upon the relative ability of nalmefene HCl and nalmefene methyliodide to penetrate the BBB, initial studies were conducted to document that nalmefene methyliodide does not block opiate receptors inside the central nervous system. While nalmefene HCl blocked morphine-induced antinociceptive responses at doses as low as 10 micrograms/kg, nalmefene methyliodide was ineffective in this regard at doses as high as 500 micrograms/kg. The luteinizing hormone (LH) suppression and prolactin (PRL) secretion induced by morphine was blocked by both nalmefene HCl and its methyliodide analogue, indicating that the opioid receptor type which mediates both responses is located outside the BBB. We observed that basal PRL levels were reduced by nalmefene HCl but not by nalmefene methyliodide indicating that basal PRL secretion is influenced by opioid neurons inside the BBB. While nalmefene HCl blocked morphine-induced suppression of thyroid-stimulating hormone (TSH) release, nalmefene methyliodide was less effective, suggesting that opiate-induced TSH suppression may be mediated by receptors located both within and outside the BBB. Nalmefene HCl caused a growth hormone (GH)-secretory response by itself, but nalmefene HCl and nalmefene methyliodide were ineffective in blocking morphine-induced GH secretion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in the molecular structure of mouse fetal astrocyte nucleosomes produced in vitro by methylmercuric chloride

The fluorescent probe N-(3-pyrene)maleimide, which specifically labels the cysteine residues of histone H3 within the nucleosome, was used to monitor changes in the nucleosomal structure of mouse fetal astrocytes exposed to varying concentrations of methylmercuric chloride. Methylmercuric chloride treatment (10 microM) for 6 hr produced a significant decrease in the degree of fluorescence of the probe. The decrease was much smaller following a 4-hr incubation period. These results correlate with recent observations showing that significant changes in the thymidine labeling index occur following 4-6 hr of exposure to methylmercury (MeHg). It is hypothesized that MeHg enters the cells during the growth phase and attaches to the protein moiety of the nucleosome in or near the cysteine groups of histone H3, thus diminishing the binding capacity of the fluorescent probe. Addition of a detergent (sodium dodecyl sulfate) resulted in only a small increase in the degree of fluorescence of the treated nucleosomes as compared to controls, showing that the interaction of MeHg with the nuclear proteins was not dissociated by detergent. In view of the strong interaction between DNA and the histone dimer H3-H4 and the potential importance of the latter in gene regulation, these results suggest an additional means by which MeHg may exert its toxic effects.     

The interaction of platinum antitumour drugs with mouse liver mitochondria.

A study was undertaken to determine if cis-DDP and its second generation derivatives produced effects on mouse liver mitochondria, and if any of the observed effects could be correlated with the nephrotoxicity of the drugs. Although changes were observed in mitochondrial morphology, enzyme activity, Ca2+ influx, terbium binding and surface potential, no specific effect was correlated with nephrotoxicity. cis-DDP produced marked changes in mitochondrial morphology; electron probe analysis showed binding of the drug to the mitochondria. Inhibition of complex I and II activity of the respiratory chain and an ionic-strength-dependent effect on Tb3+ (a Ca2+ analogue) fluorescence were observed. The non-nephrotoxic derivatives, CHIP and tetraplatin, also produced significant changes in morphology. Treatment with these derivatives also produced decreases in mitochondrial enzyme activity, but the effect on terbium binding had an ionic-strength dependence which was inverse to that observed with cis-DDP. The tetravalent compounds also had a notable effect on mitochondrial surface potential. Carboplatin had an effect on morphology and Ca2+ influx and it inhibited the respiratory enzymes, although in a manner different from that observed with cis-DDP. Carboplatin had a minimal effect on terbium binding. It is evident that if the platinum drugs enter a cell to exert their action at the nuclear level, they will also depress mitochondrial function. The observed effects did not correlate with nephrotoxicity but, since all four compounds significantly altered mitochondrial structure and function, they may be related to the cytotoxicity of the drug.     

Measurement of self-esteem in repeat assault victims.

Background characterization of assault-related injuries have demonstrated that lifestyle, substance abuse, education, employment, mental illness, and high-risk behavior contribute to low self-esteem in repeat assault victims. Recurrent-assault patients have never been studied with respect to self-esteem. This study evaluated self-esteem and assault-related injury in 28 consecutive male assault patients (11 first-assault and 17 recurrent-assault patients) and 19 controls with no previous assault history. Study participants were administered the Walmyr Assessment Scales Index of Self-Esteem (WASISE) as part of a three-item survey to determine the relationship between self-esteem and assault-related injury. No demographic differences were found between the groups. The mean (+/- standard error) WASISE score for recurrent-assault patients (34.9 +/- 3.4) was significantly higher than mean scores for no-assault and first-time assault-injured patients (14.7 +/- 1.4 and 15.0 +/- 2.3, respectively). The recurrent-assault patients had a lower mean education level than both no-assault and first-time assault-injured patients (2.1 +/- 0.26 and 1.9 +/- 0.57, respectively). Eighteen (2%) first-time assault-injured and 11 (7%) recurrent-assault patients were employed. These data suggest that self-esteem, education, and employment history need to be considered when evaluating and developing interventions for repeat-assault patients.     

Regional changes in monoamine metabolism in the aging constant estrous rat

Studies were undertaken to determine levels of monoamines and their metabolites in brain regions in young (3–4 months) normally cycling and old (25–26 month) constant estrous female rats. Dopamine (DA) concentrations were reduced in old rats in the median eminence (ME), medial basal hypothalamus (MBH), preoptic area-anterior hypothalamus (POA-AH) and the striatum. Similarly, concentrations of dihydroxyphenylacetic acid (DOPAC), the major acid metabolite of DA, were reduced significantly in all 4 regions. In the ME, a strong positive correlation was observed between DA and DOPAC concentrations in both young and old rats. Concentrations of norepinephrine (NE) were reduced in old rats in the MBH and POA-AH but not in the ME or striatum. Concentrations of serotonin (5HT) and its major metabolite, 5-hydroxyindoleacetic acid (5HIAA) were generally unchanged with age in all of the regions examined. These studies indicate the age-related regional alterations in DA and 5HT metabolism can be monitored by methods which quantitate monoamines and their metabolites.     

The role of conditioned taste aversion in the suppression of food intake by estradiol

In three experiments, ovariectomized rats were given a familiar or novel diet prior to treatment with a brain-enhanced estradiol-chemical delivery system (E2-CDS, 1 mg/kg). Experiment 1 showed that food intake was suppressed in subjects receiving either diet, but animals given a novel diet initially showed a profound anorexia which eventually recovered to the moderate suppression of animals given the familiar diet. In Experiment 2, rats showed an aversion to a novel diet paired with the E2-CDS in a two-choice preference test given on Day 2 after the injection, indicating that the initial large reduction in intake was mediated by a conditioned taste aversion. However, no aversion was observed seven days after the E2-CDS, suggesting that the residual intake suppression was mediated by unconditioned aversion or appetite suppression. Experiment 3 showed that lengthening the postovariectomy time resulted in a taste aversion that persisted for a longer duration.     

An acute granular lymphoid leukemia with unusual cytochemistry and immunologic phenotype

A 15-year-old Mexican boy presented with an L2 type acute lymphoid leukemia (ALL). Occasional granulated and hand mirror cells were observed, and enzyme histochemistry showed the blasts to be positive for acid phosphatase, beta glucuronidase, and alpha napthyl butyrate esterase. Immunologic studies showed the cells to stain for terminal deoxynucleotidyl transferase and common ALL antigen and to react with B4 (90 per cent), B1 (60 per cent), and B2 (37 per cent) monoclonal antibodies. T-cell-associated antigens (T1, T4, T6, T8, T11) were present in only 10 per cent or less of the cells. Monoclonal antibodies for granulocytes and monocytes were negative. Surface immunoglobulin was absent. Chromosome studies showed a normal phenotype. Clinically, the patient did well, achieving a remission on a high risk ALL protocol. The case shows a marked dichotomy between enzyme histochemistry and immunologic monoclonal antibody markers and is an unusual case of granulated hand mirror lymphoblastic leukemia of pre-B cell origin.     

Quinol-based metabolic cycle for estrogens in rat liver microsomes.

According to a recently reported metabolic pathway, phenolic A-ring estrogens are metabolized in rat liver microsomes partially to the corresponding quinols by cytochrome P450 isoenzymes. We found that these quinols could, in turn, undergo reduction to regenerate the parent estrogens consumed during the metabolic process. Among the tested endogenous reducing agents, NADH and especially NADPH produced a significant extent of reductive conversion. Enzymes available in rat liver microsomes further catalyzed this reaction with 6.5 +/- 1.5 nmol. min(-1). (mg of protein)(-1) measured as the initial rate of estrone formation at 37 degrees C, whereas the initial rate of second-order reaction for the reduction of E1-quinol by a 10-fold excess of NADPH in a microsome-free buffer solution and under identical incubation conditions was 0.62 +/- 0.03 nmol. min(-1). The quinol route is, therefore, unique among estrogen-metabolizing pathways for its bioreversibility due to the facile regeneration of the phenolic A-ring estrogens consumed in the preceding oxidative process.