Biomedical subjects

S Mortaud

Publications and source records attributed to S Mortaud.

7 recordsLinked to original sources

PubMed2001

Aggressive behavior induced by the steroid sulfatase inhibitor COUMATE and by DHEAS in CBA/H mice.

The steroid sulfatase enzyme (STS) regulates the formation of dehydroepiandrosterone (DHEA) from dehydroepiandrosterone-sulfate (DHEAS). DHEAS is a well-known negative allosteric modulator of the GABA(A) receptor-gated chloride channels. It is classified as an excitatory neurosteroid. The implication of GABA(A) receptor activity in aggressive behavior in rodents is well-documented. In addition a genetic correlation between STS level in the liver and aggressive behavior across 12 strains of mice suggest that STS activity could be involved in aggression in mice. We assessed herein whether COUMATE (an STS inhibitor) and DHEAS modulate aggression in CBA/H mice. We hypothesized that inhibiting STS activity in vivo followed by DHEAS injections which increase the level of sulfated steroid that cross the blood-brain barrier and then modulate neurotransmitter receptors could modify the attack behavior in mice. COUMATE (10 mg/kg) was administrated p.o. alone or in combination with the neurosteroid DHEAS (0-50 mg/kg) i.p. Animals were thereafter tested for aggression. A single dose of COUMATE significantly inhibited STS activity both in the brain (70.57%) and in the liver (87%) 24 h following administration. Behavioral tests showed that the inhibitor and DHEAS enhanced aggressive behavior when animals were simultaneously subjected to both molecules. These results confirm the correlation between aggressive behavior and STS concentration in mice. In addition, we confirm that the steroid metabolism can modulate the behavior in rodents.

Aggression↗

PubMed2000

Loss of aggression, after transfer onto a C57BL/6J background, in mice carrying a targeted disruption of the neuronal nitric oxide synthase gene.

Phenotypic differences among mice with disrupted genes and those with wild-type alleles have not provided the necessary evidence for desired gene/phenotype correlations. These differences could be due to "passenger genes" from the donor 129 strains that are used to produce stem cells. Three variations of attack behavior were measured, using mice carrying a disruption of the neural nitric oxide synthase gene. In the first population, the disrupted gene had been maintained on a mixed background including C57BL/6J and 129 alleles. We have developed a second population in which the disrupted gene was transferred onto a C57BL/6J background during five backcross generations. On the mixed C57BL/6J-129 background, mice homozygous for disrupted Nos1 alleles attacked more frequently, had shorter attack latencies, and presented a greater number of attacks than mice carrying nondisrupted alleles. On the C57BL/6J background, no significant difference persisted between the carriers of the disrupted gene and their noncarrier siblings. The noncarriers on the mixed C57BL/6J-129 background, and the carriers or noncarriers on the C57BL/6J background, did not differ from C57BL/6J. The frequency of attacking males was identical in the homozygous carriers of the disrupted gene, in the mixed C57BL/6J-129 background, and in the 129/SvPas, which approximates the 129/SvJae strain from which the stem cells were derived to produce the disrupted Nos1 gene. These results suggest that Nos1 disruption was not implicated in attack behavior. A possible passenger-gene effect from the 129 donor strain is discussed.

Aggression↗

PubMed1999

Genetic correlation between steroid sulfatase concentration and initiation of attack behavior in mice.

The pairing region of the X-Y chromosomes recombines at male meiosis. We previously found that offense behavior in male mice, measured by initiation of attack against a conspecific male, was linked to this region. Only one functional gene (coding for steroid sulfatase or Sts) is mapped on this region as of yet, suggesting that it could be a candidate for offense behavior. We estimated the genetic correlation between the concentration of STS protein in the liver and the initiation of attack behavior in 11 strains of inbred mice. The high correlation (close to reliability) coefficient of the behavioral phenotype indicates the implication of STS in offense behavior. Recent investigations have demonstrated the involvement of STS in neurosteroid biochemical pathways, and several lines of evidence indicate that neurosteroids interact with neurotransmitters. These conclusions and our present results support the hypothesis that sulfatation of steroids may be the prime mover of a complex network, including genes shown to be implicated in aggression by mutagenesis.

Aggression↗

PubMed1998

Neuronal and behavioral differences between Mus musculus domesticus (C57BL/6JBy) and Mus musculus castaneus (CAST/Ei).

Previous studies have demonstrated that classical inbred strains of laboratory mice do not exhibit large genetic distances when simple sequence repeats (SSRs) are used to test for their polymorphisms whereas mice from wild origin exhibit high polymorphisms (more than 90%) for these sequence when compared with classical inbred strains of laboratory mice. The difference between Mus musculus castaneus and C57BL/6J reaches 98% and F1s male and female are fertile. These two properties pave the way for gene mapping derivating segregating generations between these strains. The phenotypical characteristics of Mus musculus castaneus have not been investigated, unfortunately. The first screening of Mus musculus castaneus and C57BL/6By was carried out for sensorial and motor development, spontaneous behavior in new environment, paw preference, maternal behavior, aggression in two different situations and time to learn escape in a water maze. Morphometry of hippocampus and weight of the male reproductive organs for measures that have been reported to be correlated with several of the examined behavior are also reported. The authors tested also reactivity to one drug (beta-CCM) revealing seizure proneness. The two strains differ for 69% of the reported measures. Comparison to other strains for the same measures obtained in the laboratory for identical tests with mice reared in identical situations provided the mean to compare Mus musculus castaneus with a large set of more or less traditional mice. This strain has the most extreme position for 80% of the comparisons.

Aggression↗

PubMed1996

Murine steroid sulfatase gene expression in the brain during postnatal development and adulthood.

The microsomal enzyme steroid sulfatase (STS, E.C.3.1.6.2) plays a central function in the neurosteroid mode of action, since it is responsible for the switch between the sulfated and the free forms of steroids which have opposite effects. In this study, using an enzyme linked immunosorbent assay (ELISA) for the STS, we have investigated the brain expression of STS in mice during development. We confirm that STS is present in the brain as previously shown by the measurement of the enzymatic activity. At birth, the STS level is clearly higher than in adults. We observed differences between physiological stages in females brain. The STS level is the same in pregnant and non-pregnant females, whereas STS concentration dramatically increased after delivery and during lactation.

Age Factors↗

PubMed1996

Steroid control of higher brain function and behavior.

In higher vertebrates, many behavioral characteristics can be attributed to effects in the central nervous system, in response to gonadal hormones secreted early in development. The lipophilic properties of steroids facilitate their easy passage in free form through the blood-brain barrier. At the cerebral level, the function of many nerve cells is influenced by steroid hormones originating from the periphery (synthesis of gluco-, and mineralo-corticosteroids in the adrenal glands and of sex steroids in the gonads and the placenta from cholesterol). However, the relationship between steroids and cerebral function may need reconsidering in light of the recent discovery of a biosynthetic pathway (independently of peripheral sources) of steroidal compounds ensuring the synthesis of neurosteroids from cholesterol in certain brain cells.

Animals↗

PubMed1995

Murine steroid sulfatase (mSTS): purification, characterization and measurement by ELISA.

The murine steroid sulfatase (mSTS) is a microsomal enzyme, important in steroid metabolism. In the mouse, the gene encoding mSTS is pseudoautosomal and thus escapes X-inactivation. We have purified steroid sulfatase approximately 30-fold from mouse liver microsomes and its properties have been investigated. The major steps in the purification procedure included solubilization with Triton X-100, gel filtration chromatography, DEAE-Sephadex chromatography and HPLC gel filtration chromatography. The purified sulfatase showed a relative molecular weight of 128 kDa on HPLC gel filtration, whereas the enzyme migrated as two bands of 60 and 68 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isoelectric point of steroid sulfatase was estimated to be 6.2 by column chromatofocusing. Polyclonal antibodies to the purified protein were prepared. An Enzyme Linked Immunosorbent Assay (ELISA) was developed using purified monospecific anti-mSTS antibodies labelled with peroxidase. The standard criteria of precision and reproducibility were satisfied. The assay was applicable to routine determination of mSTS samples in research laboratories. Differences in mSTS liver concentrations were used to identify putative alleles for the mSTS gene (Sts). Results in ELISA confirmed the polymorphism previously demonstrated for an enzymatic mSTS activity assay in two inbred mouse strains.

Animals↗