Repeated predictable or unpredictable stress: effects on cocaine-induced locomotion and cyclic AMP-dependent protein kinase activity

Stressful experiences appear to have a strong influence on susceptibility to drug taking behavior. Cross-sensitization between stress and drug-induced locomotor response has been found. Locomotor response to novelty or cocaine (10 mg/kg, i.p.), cyclic AMP-dependent protein kinase (PKA) activity in the nucleus accumbens and basal corticosterone levels were evaluated in male adult rats exposed to acute and chronic predictable or unpredictable stress. Rats exposed to a 14-day predictable stress showed increased locomotor response to novelty and to cocaine, whereas rats exposed to chronic unpredictable stress demonstrated increased cyclic AMP-dependent PKA activity in the nucleus accumbens. Both predictable and unpredictable stress increased basal corticosterone plasma levels. These experiments demonstrated that stress-induced early cocaine sensitization depends on the stress regime and is apparently dissociated from stress-induced changes in cyclic AMP-dependent PKA activity and corticosterone levels. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Repeated exposure of adolescent rats to oral methylphenidate does not induce behavioral sensitization or cross-sensitization to nicotine

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Repeated administration of caffeine induces either sensitization or tolerance of locomotor stimulation depending on the environmental context

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Pregnancy outcomes in women with repeated implantation failures after intracytoplasmic morphologically selected sperm injection (IMSI)

Background: The purpose of this study was to compare laboratory and clinical outcomes of intracytoplasmic morphologically selected sperm injection (IMSI) and conventional intracytoplasmic sperm injection (ICSI) in couples with repeated implantation failures.Methods: A total of 200 couples with at least two prior unsuccessful ICSI cycles were enrolled: 100 couples were submitted to IMSI and 100 were submitted to routine ICSI. For IMSI, spermatozoa were selected at 8400x magnification using an inverted microscope equipped with Nomarski (differential interference contrast) optics. For conventional ICSI, spermatozoa were selected at 400x magnification. Clinical outcomes were evaluated between the two groups.Results: Study patients were comparable in age, number of treatment failures, aetiology of infertility, percentage of normal form assessed by MSOME (motile sperm organelle morphology examination), semen parameters, total number of oocytes collected, number of mature oocytes collected, total number of embryos transferred and number of high-quality embryos transferred. No statistically significant differences between the two groups were observed with regard to rates of fertilisation, implantation and pregnancy/cycle. Although not statistically significant, rates of miscarriage (IMSI:15.3% vs ICSI:31.7%), ongoing pregnancy (IMSI:22% vs ICSI:13%) and live births (IMSI:21% vs ICSI:12%) showed a trend towards better outcomes in the IMSI group. In addition, analysis of subpopulations with or without male factor showed similar results.Conclusions: Our results suggest that IMSI does not provide a significant improvement in clinical outcome compared to ICSI, at least in couples with repeated implantation failures after conventional ICSI. However, it should be noted that there were clear trends for lower miscarriage rates (approximate to 50% reduced) and higher rates of ongoing pregnancy and live births (both nearly doubled) within the IMSI group. Further confirmation as well as randomized large-scale trials are needed to confirm the beneficial effects of IMSI in couples with poor reproductive prognoses.

Cholesterol reduction and lack of genotoxic or toxic effects in mice after repeated 21-day oral intake of lemongrass (Cymbopogon citratus) essential oil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Patterns of Gene Expression in the Bovine Corpus Luteum Following Repeated Intrauterine Infusions of Low Doses of Prostaglandin F2alpha

Natural luteolysis involves multiple pulses of prostaglandin F2alpha (PGF) released by the nonpregnant uterus. This study investigated expression of 18 genes from five distinct pathways, following multiple low-dose pulses of PGF. Cows on Day 9 of the estrous cycle received four intrauterine infusions of 0.25 ml of phosphate-buffered saline (PBS) or PGF (0.5 mg of PGF in 0.25 ml of PBS) at 6-h intervals. A luteal biopsy sample was collected 30 min after each PBS or PGF infusion. There were four treatment groups: Control (n = 5; 4 PBS infusions), 4XPGF (4 PGF infusions; n = 5), 2XPGF-non-regressed (2 PGF infusions; n = 5; PGF-PBS-PGF-PBS; no regression after treatments), and 2XPGF-regressed (PGF-PBS-PGF-PBS; regression after treatments; n = 5). As expected, the first PGF pulse increased mRNA for the immediate early genes JUN, FOS, NR4A1, and EGR1 but unexpectedly also increased mRNA for steroidogenic (STAR) and angiogenic (VEGFA) pathways. The second PGF pulse induced immediate early genes and genes related to immune system activation (IL1B, FAS, FASLG, IL8). However, mRNA for VEGFA and STAR were decreased by the second PGF infusion. After the third and fourth PGF pulses, a distinctly luteolytic pattern of gene expression was evident, with inhibition of steroidogenic and angiogenic pathways, whereas, there was induction of pathways for immune system activation and production of PGF. The pattern of PGF-induced gene expression was similar in corpus luteum not destined for luteolysis (2X-non-regressed) after the first PGF pulse but was very distinct after the second PGF pulse. Thus, although the initial PGF pulse induced mRNA for many pathways, the second and later pulses of PGF appear to have set the distinct pattern of gene expression that result in luteolysis.

HARDNESS and SURFACE ROUGHNESS of RELINE and DENTURE BASE ACRYLIC RESINS AFTER REPEATED DISINFECTION PROCEDURES

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

High-Intensity Resistance Training with Insufficient Recovery Time Between Bouts Induce Atrophy and Alterations in Myosin Heavy Chain Content in Rat Skeletal Muscle

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Chromosome Evolution in African Cichlid Fish: Contributions from the Physical Mapping of Repeated DNAs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Organization of Repeated DNA Elements in the Genome of the Cichlid Fish Cichla kelberi and Its Contributions to the Knowledge of Fish Genomes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Repeated unrewarded scent exposure influences the food choice of stingless bee foragers, Melipona scutellaris

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

THE RATE of FORCE DEVELOPMENT OBTAINED AT EARLY CONTRACTION PHASE IS NOT INFLUENCED BY ACTIVE STATIC STRETCHING

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Repeated administration intensifies the reinforcing effect of fencamfamine in rats

1. In the present study, we evaluated the role of repeated administration on conditioning place preference (CPP) induced by fencamfamine (FCF) in male rats.2. Repeated FCF (3.5 mg/kg) or saline once or daily for ten consecutive days enhanced sniffing du ration and decreased locomotion and rearing duration.3. At the 3.5 mg/kg dose, FCF produced a significant place-preference effect.4. Repeated exposures to FCF intensified its reinforcing properties.5. These results suggest that repeated FCF administration sensitizes its rewarding effects, as with other addictive substances. GEN PHARMAC 29;2:265-261, 1997. (C) 1997 Elsevier B.V.

Noradrenergic response in vas deferens from rats submitted to acute and repeated stress

1. This work investigated the effects of androgens on the norepinephrine sensitivity of vasa deferentia from rats submitted to acute or repeated stress, as well as the participation of alpha(1)-adrenoceptors in the response of intact and bisected vasa deferentia from adult normal rats submitted to acute or repeated stress.2. The acute stress produced subsensitivity to norepinephrine only in intact vasa deferentia from adult normal rats, which was prevented by lack of androgens, suggesting that the sensitivity may be dependent on the physiological level of androgen,3. No change was observed in intact vas deferens sensitivity to norepinephrine in repeated stress, suggesting the occurrence of adaptation to elevated norepinephrine levels or a mild decrease in androgen levers or both.4. The changes in sensitivity observed in acute and repeated stress may also be due to alterations in alpha(1)-adrenergic receptors that are located in the prostatic portion of the vas deferens. (C) 1998 Elsevier B.V.