Effects of subacute treatment with cocaine on activities of N-demethylase, UDP-glucuronyltransferase and sulfotransferase in WKY and SHR rat liver--sex and strain differences

The effects of subacute treatment with cocaine on activities of cocaine N-demethylase, UDP-glucuronyltransferase (GT) toward 4-nitrophenol and phenolphthalein and sulfotransferase (ST) toward androsterone and 4-nitrophenol in livers from Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were investigated. Hepatic metabolism of cocaine was different between the sexes (with males having higher N-demethylase activity) and the strains (with WKY rats having higher activity). The effects of subacute cocaine administration on the activity of cocaine N-demethylase were also sex- and strain-related. Whereas cocaine administration increased activity of hepatic N-demethylase in both female strains, it decreased activity in male WKY and had no effect on activity in male SHR. Sex and strain-related as well as cocaine-induced differences were also found in activities of hepatic GT toward 4-nitrophenol and phenolphthalein as well as in activity of hepatic ST towards andersterone and 4-nitrophenol. These results suggest that some of the individual variation in the effects of cocaine may be due to sex and genetic differences in the hepatic metabolism of cocaine and/or in sexually and/or/genetically-determined differences in how cocaine affects hepatic metabolism of other xenobiotics.     

Low molecular weight factor in bovine caudal epididymal fluid that stimulates calcium uptake in caput spermatozoa

Secretions from the mammalian epididymis contain proteins that bind to developing sperm and are presumed to play a role in sperm maturation. The biochemical functions in sperm of most of these proteins are not known. In this report we describe the presence of a low molecular weight compound in bovine caudal epididymal luminal fluid (CF) that has a potent stimulatory effect on calcium (⁴⁵Ca²⁺) uptake in immature caput epididymal spermatozoa. The studies were initially undertaken to characterize the effect of the protein caltrin, present in bovine seminal plasma (BSP), on calcium uptake into caput spermatozoa. Caltrin is known to block calcium influx into mature bovine sperm. Unexpectedly, the kinetics of calcium uptake into caput sperm showed a biphasic response when treated with BSP, namely, a stimulation of uptake at 1 to 5 min and inhibition of uptake after this time. Since caudal sperm do not show this biphasic response, we reasoned that BSP contained a factor derived from CF that must interact with developing sperm before the binding of caltrin to sperm can prevent further calcium uptake. We first demonstrated that preincubation of caput sperm with CF eliminated the biphasic calcium uptake effect induced in caput sperm by BSP and that caudal fluid alone had a potent stimulatory effect on calcium uptake in caput sperm. Half-maximal stimulation (fivefold over control) occurred at a caudal fluid protein concentration of 0.27 mg/ml. Partial purification of the factor indicates that it is of low molecular weight (MW ～ 1,000), but further chemical characterization has not been carried out and its epididymal site of origin is not known. The results indicate that the regulation of intracellular calcium levels in sperm differs in immature and mature bovine sperm in that an epididymal factor promotes calcium uptake during epididymal maturation, and the seminal fluid protein caltrin prevents it at ejaculation.     

Differential distribution of endothelin peptides and receptors in human adrenal gland

Summary Sub-type selective ligands revealed a differential distribution of endothelin (ET) receptors within human adrenal glands. High densities of ET_A receptors were localized, using [¹²⁵I]-PD151242, to the smooth muscle layer of the arteries, smaller vessels within the capsular plexus and to the secretory cells of zona glomerulosa (K _D=139.8±39.7,B _max=69.7±9.1 fmol mg⁻¹ protein, mean of 3 individuals±sem). ET_B receptors were present in the medulla (K _D=145.2±16.4,B _max=75.5±12.3), zona glomerulosa (K_D=100.6±35.1,B _max=63.1±10.0), fasiculata (K _D 145.1±162.,B _max=67.9±6.9) and reticularis (K_D=118.2±18.6,B _max=71.9±6.5). ET_B receptors were not detected within the smooth muscle of the vasculature. Messenger RNA encoding both sub-types was present in adrenals. ET-like immunoreactivity was localized to the cytoplasm of the endothelial cells from arteries supplying the gland and resistance vessels within the capsular plexus. Staining was also detected in these cells using anti-big ET-1 and less intensely with anti-big ET-2 antisera but not within cells within the cortex or medulla. Big ET-3-like immunoreactivity was localized to secretory cells of the medulla. Staining was not found using antiserum that could detect ET-3, suggesting further processing of big ET-3 may occur within the plasma, and that the cdrenals could be a source of ET-3. The presence of ET-1 was confirmed by high performance liquid chromatography and radioimmunoassay although ET-3 was not detected. The results suggest that ET-1 is the predominant mature isoform, which is localized mainly to adrenal vasculature, particularly the capsular plexus, and may contribute to blood flow regulation in the gland.     

Site and mechanism of behavioral tolerance to cocaine: A study of dopamine release in Wistar-Kyoto and spontaneously hypertensive rats

Wistar-Kyoto and spontaneously hypertensive rats received i.v. infusions of cocaine hydrochloride (60 mg/kg per day) for 3, 7, and 14 days, or saline for 7 days. Acute cocaine challenge (40 mg/kg, s.c.) was given to treated and control rats 24 hr after the termination of each infusion period. There were no strain differences in brain levels of cocaine during cocaine infusion, nor after cocaine challenges. There were no strain differences in resting levels of [³H]dopamine release. Release of [³H]dopamine decreased in nuclei accumbens of 7- and 14-day cocaine-infused animals. Release of [³H]dopamine was maximal in both brain regions 2 hr after acute cocaine challenge. After 14 days of cocaine infusion, cocaine challenge in both strains reduced [³H]dopamine release in the nucleus accumbens, but not in the striatum; the reduction being greater in Wistar-Kyoto rats. The behavioral tolerance which accompanies similar cocaine infusion regimens may be related to striatal tolerance to cocaine-induced dopamine release.     

A major difference between the divergence patterns within the lines-1 families in mice and voles

L1 retroposons are represented in mice by subfamilies of interspersed sequences of varied abundance. Previous analyses have indicated that subfamilies are generated by duplicative transposition of a small number of members of the L1 family, the progeny of which then become a major component of the murine L1 population, and are not due to any active processes generating homology within preexisting groups of elements in a particular species. In mice, more than a third of the L1 elements belong to a clade that became active approximately 5 Mya and whose elements are > or = 95% identical. We have collected sequence information from 13 L1 elements isolated from two species of voles (Rodentia: Microtinae: Microtus and Arvicola) and have found that divergence within the vole L1 population is quite different from that in mice, in that there is no abundant subfamily of homologous elements. Individual L1 elements from voles are very divergent from one another and belong to a clade that began a period of elevated duplicative transposition approximately 13 Mya. Sequence analyses of portions of these divergent L1 elements (approximately 250 bp each) gave no evidence for concerted evolution having acted on the vole L1 elements since the split of the two vole lineages approximately 3.5 Mya; that is, the observed interspecific divergence (6.7%-24.7%) is not larger than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses showed no clustering into Arvicola and Microtus clades.      

Inflammatory cells in solid murine neoplasms. IV. Cytolytic T lymphocytes isolated from regressing or progressing Moloney sarcomas.

Highly purified suspensions of intratumoral T lymphocytes, recovered 11 and 13 days after induction of regressing or progressing Moloney sarcomas, were compared in their ability to lyse specifically the MSC cells used for tumor induction. Cytolytic activity, expressed in terms of lytic units/10(6) T cells, was similar for intratumoral T cell suspensions obtained 11 days after induction of either regressing (3.1 +/- 1.3 LU/10(6) T cells) or progressing (4.3 +/- 1.8) neoplasms. By 13 days post-induction, regressing tumors contained T lymphocytes with an increased cytolytic activity (11.1 +/- 4.5) whereas those from progressing tumors were strikingly less able to kill MSC cells (less than or equal to 0.2). This dramatic loss in cytotoxicity could not be attributed to errors associated with the enzymatic disaggregation method, inhibition by copurified endogenous tumor cells, or immunosuppression induced by viral infection. The changes in functional activity of intratumoral T lymphocytes from the two types of sarcoma appeared to be correlated with the stage of neoplasia. In this model system, cytolytic activity of T lymphocytes increased during spontaneous tumor regression whereas losses in cytotoxicity occurred coincident with the onset of inexorable progression.