Multiple pathways for cationic amino acid transport in rat seminiferous tubule cells.

Arginine and ornithine are known to be important for various biological processes in the testis, but the delivery of extracellular cationic amino acids to the seminiferous tubule cells remains poorly understood. We investigated the activity and expression of cationic amino acid transporters in isolated rat Sertoli cells, peritubular cells, pachytene spermatocytes, and early spermatids. We assessed the l-arginine uptake kinetics, Na(+) dependence of transport, profiles of cis inhibition of uptake by cationic and neutral amino acids, and sensitivity to trans stimulation of cationic amino acid transporters, and studied the expression of the genes encoding them by RT-PCR.

In vitro regulation of an inducible-type NO synthase in the rat seminiferous tubule cells.

Rat Sertoli cells express an inducible nitric oxide synthase isoform (iNOS) in response to the combined addition of the cytokines--interferon gamma (IFNgamma), tumor necrosis factor alpha (TNF alpha), interleukin-1alpha (IL-1alpha)--and lipopolysaccharides (LPS). We demonstrated that the addition of cytokines and lipopolysaccharides (C+L) to cultured peritubular cells resulted in high nitrite and iNOS mRNA levels, indicating the induction of an iNOS isoform. This enzyme was not induced in cultured pachytene spermatocytes or spermatids.

Nitric oxide production by Sertoli cells in response to cytokines and lipopolysaccharide.

Nitric oxide (NO) is formed from L-arginine residues by nitric oxide synthase (NO Synthase) in many types of cells and acts as an intercellular messenger in several physiological systems. In the present study, we demonstrate that a combination (CL) of interleukin-1 alpha, interferon gamma, tumor necrosis factor alpha and lipopolysaccharide induces nitrite (NO2) production in cultured rat Sertoli cells. This biosynthesis of NO2- requires a lag time period of 18 hr and then increases for at least 96 hr; it is prevented by two NO Synthase inhibitors, NG-monomethyl-L-arginine and aminoguanidine.

Antioxidant system in rat testicular cells.

The activity of the enzymes involved in the antioxidant defence--superoxide dismutase (SOD), glutathione peroxidase (GPx), reductase (GR), S-transferase (GST)--as well as the glutathione (GSH) levels were measured in different rat testicular cell populations. A differential distribution of these components among testicular cell types was clearly observed. Sertoli and peritubular cells had elevated SOD and GSH-dependent enzyme activities associated with a high GSH content.

[Protection of male fertility during anticancer treatment: animal experiments].

One of the best known iatrogenic effects of anticancer treatments is the sterility of young patients with a good prognosis, hence the necessity to develop a protocol enabling us to preserve male reproductive function. This review of the literature summarises the various approaches investigated in order to obtain protection of spermatogenesis prior to radiotherapy and/or chemotherapy. Most of these pathways involve hormone therapy based on regulation of the hypothalamo-hypophyso-testicular axis.

Protective effect of medroxyprogesterone acetate plus testosterone against radiation-induced damage to the reproductive function of male rats and their offspring.

This study attempted to protect spermatogenesis and the reproductive performance of rats against the effects of acute scrotal exposure to x-rays. Daily subcutaneous injections of medroxyprogesterone acetate (8 mg/kg) plus testosterone (1 mg/kg) (MT group) were administered for 55 days (experiment A) or 15 days (experiment B). The rats were irradiated (3 grays) on the last day of MT pretreatment (MTX group).

Ethanol alters the adenosine receptor-Ni-mediated adenylate cyclase inhibitory response in rat brain cortex in vitro.

It has been suggested that ethanol stimulates adenylate cyclase in vitro through an increased function of Ns, the activatory component of adenylate cyclase. Because of the interaction of Ns with Ni, the adenylate cyclase inhibitory component, we have studied the effect of ethanol (0.05-0.

Inhibition in vitro of acyl-CoA dehydrogenases by 2-mercaptoacetate in rat liver mitochondria.

In rat liver hypo-osmotically treated mitochondria, 2-mercaptoacetate inhibits respiration induced by palmitoyl-CoA, octanoate or butyryl-CoA only when the reaction medium is supplemented with ATP. Under this condition, NADH-stimulated respiration is not affected. In liver mitochondrial matrix, the presence of ATP is also required to observe a 2-mercaptoacetate-induced inhibition of acyl-CoA dehydrogenases tested with palmitoyl-CoA, butyryl-CoA or isovaleryl-CoA as substrate.

Effects of 2-mercaptoacetate in isolated liver mitochondria in vitro. Competitive inhibition of 3-hydroxybutyrate dehydrogenase and depression of the beta-oxidation pathway.

The effects of 2-mercaptoacetate on the respiration rates induced by different substrates were studied in vitro in isolated liver mitochondria. With palmitoyl-L-carnitine or 2-oxoglutarate as the substrate, the ADP-stimulated respiration (State 3) was dose-dependently inhibited by 2-mercaptoacetate. with glutamate or succinate as the substrate.

2-Mercaptoacetate administration depresses the beta-oxidation pathway through an inhibition of long-chain acyl-CoA dehydrogenase activity.

To elucidate the mechanisms through which 2-mercaptoacetate administration inhibits fatty acid oxidation in the liver, the respiration rates induced by different substrates were studied polarographically in rat hepatic mitochondria isolated 3 h after 2-mercaptoacetate administration. Palmitoyl-L-carnitine oxidation was almost completely inhibited in either the absence or presence of malonate. Octanoate oxidation was also inhibited, and the intramitochondrial acyl-CoA content was markedly increased.

Loss of the lipoprotein lipase activating ability of rat serum after administration of some fatty liver inducing drugs.

The effects of the administration of different fatty liver inducing drugs on the serum lipoprotein lipase activating ability was investigated in rats. Addition of serum from 2-mercaptoethanol-, 2-mercaptoacetate-, ethionine- or D-galactosamine- treated rats failed to activate heart and adipose tissue lipoprotein lipase from control rats. The activating effect of serum was only slightly reduced in isopropanol-treated rats, whereas it was found unaffected in ethanol-treated ones.