Sexual behavior and fertility of male rats submitted to prolonged immobilization-induced stress.
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In order to investigate whether prolonged stress interferes with the onset of sexual behavior at puberty and with fertility at adulthood, prepubertal male Wistar rats (40 days of age) were immobilized 6 h a day for 15 days (up to early puberty) or for 60 days (until sexual maturity). Pubertal stressed rats showed a two-fold increase in the latency for the first mount (probably due to repeated aversive experience in which a change of environment was always followed by immobilization) and a 2.5-fold increase in the frequency of thrusting (indicative of enhanced sexual performance). The apparently stimulatory effect of prolonged stress on the onset of sexual behavior is discussed in terms of increased testosterone level and interference with the complex interchanges between the neurotransmitters/neuropeptides involved in the central control of male sexual activity. Adult stressed animals were mated with normal females, which became pregnant but exhibited a more than two-fold increase in both pre-implantation and post-implantation loss, probably due to a smaller rate of fertilization and/or fertilization with damaged spermatozoa. (+info)
Repeated phencyclidine treatment induces negative symptom-like behavior in forced swimming test in mice: imbalance of prefrontal serotonergic and dopaminergic functions.
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Repeated treatment with phencyclidine (PCP) prolonged the immobility time in a forced swimming test, compared with saline treatment, this behavioral change being regarded as avolition which is one of the negative symptoms of schizophrenia. In the present study, we investigated an involvement of serotonergic (5-HTergic) and dopaminergic systems in PCP-induced enhancement of immobility in mice, since an alteration in 5-HTergic and dopaminergic systems has been hypothesized in schizophrenia. The enhancing effect of PCP on the immobility in a forced swimming test was attenuated by clozapine, risperidone and olanzapine, which have serotonin (5-HT) and dopamine receptor antagonistic properties. These attenuating effects were significantly antagonized by a 5-HT(2) receptor agonist, (+/-)-2,5-dimethoxy-4-iodamphetamine (DOI) without affecting the immobility itself. (-)Sulpiride at a low dose and methylphenidate reversed the PCP-induced enhancement of immobility whereas pimozide, chlorpromazine and levomepromazine had no effect. There was no difference in the frequency of DOI-induced head twitches, which are mediated via 5-HT(2) receptors, between PCP- and saline-treated mice following the forced swimming test, indicating no functional changes in post-synaptic 5-HT(2) receptors. 5-HT utilization in the prefrontal cortex was increased, but dopamine utilization was decreased in mice showing PCP-induced enhancement of immobility. These results suggest that the enhanced effect of PCP on the immobility is mediated by imbalance of 5-HTergic and dopaminergic systems in the prefrontal cortex and could be used as a model of the negative symptoms of schizophrenia. (+info)
Tuberculin responses and risk of pneumonia in immobile elderly patients.
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BACKGROUND: Delayed type hypersensitivity (DTH) response to tuberculin is an important marker of T helper 1 (Th1) mediated acquired immunity against tuberculosis. Depressed DTH responses to tuberculin are observed in immobile elderly individuals with reduced activities of daily living (ADL) scores. Immobility in older people increases the risk of pneumonia related mortality. The decline in the competence of the immune system might be a reason for the increased susceptibility to infection in the elderly and the depressed DTH response to tuberculin might be a predictor for increased risk of pneumonia. METHOD: The DTH responses to tuberculin were examined in 49 older patients with limited ADL of similar severity, all of whom had a past history of positive DTH responses to tuberculin. Responses with an induration diameter of >/=10 mm were considered positive. Reactivities of Th1 and Th2 lymphocytes taken from the peripheral blood of each subject were also examined and compared between the positive tuberculin responders and the negative tuberculin responders. The rates of pneumonia in these groups were then compared prospectively for two years. RESULTS: The number of CD4 lymphocytes differed significantly between patients with a positive tuberculin response (n=22, mean (SE) 1018 (118) x 10(6)/l) and those with a negative response (n=27, 666 (80) x 10(6)/l, p=0.02). Likewise, the number of Th1 cells was significantly higher in positive tuberculin responders than in negative responders (276 (5.8) x 10(6)/l versus 149 (14) x 10(6)/l, p=0.01). However, the numbers of Th2 cells were similar between patients with positive and negative responses (22 (3) x 10(6)/l versus 19 (3) x 10(6)/l, p=0.41). During the follow up period new pneumonia was diagnosed in 18 (67%) of the 27 negative tuberculin responders and in seven (31%) of the 22 positive tuberculin responders. According to the Cox regression model, a hazard ratio of developing pneumonia in patients with a negative tuberculin response compared with those with a positive tuberculin response was 2.57 (95% CI 1.12 to 6.17, p=0.03). CONCLUSION: The diminished DTH response to tuberculin may be a predictor for increased risk of pneumonia in elderly disabled patients. (+info)
IGF-I restores satellite cell proliferative potential in immobilized old skeletal muscle.
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One of the key factors responsible for the age-associated reduction in muscle mass may be that satellite cell proliferation potential (number of doublings contained within each cell) could become rate limiting to old muscle regrowth. No studies have tested whether repeated cycles of atrophy-regrowth in aged animals deplete the remaining capacity of satellite cells to replicate or what measures can be taken to prevent this from happening. We hypothesized that there would be a pronounced loss of satellite cell proliferative potential in gastrocnemius muscles of aged rats (25- to 30-mo-old FBN rats) subjected to three cycles of atrophy by hindlimb immobilization (plaster casts) with intervening recovery periods. Our results indicated that there was a significant loss in gastrocnemius muscle mass and in the proliferative potential of the resident satellite cells after just one bout of immobilization. Neither the muscle mass nor the satellite cell proliferation potential recovered from their atrophied values after either the first 3-wk or later 9-wk recovery period. Remarkably, application of insulin-like growth factor I onto the atrophied gastrocnemius muscle for an additional 2 wk after this 9-wk recovery period rescued approximately 46% of the lost muscle mass and dramatically increased proliferation potential of the satellite cells from this muscle. (+info)
Prostate cancer risk in relation to anthropometry and physical activity: the National Health and Nutrition Examination Survey I Epidemiological Follow-Up Study.
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We studied the relationship of prostate cancer to anthropometry and self-reported physical activity among 5377 African-American and Caucasian participants in the National Health and Nutrition Examination Survey I cohort. The cohort was first examined between 1971 and 1975 and then followed prospectively through the Epidemiologic Follow-up Study in 1982-1984, 1986, 1987, and 1992. Men who reported low levels of nonrecreational physical activity had increased risk of prostate cancer compared with very active men. These findings were unchanged after adjustment for potential confounders and were stronger for African-Americans (relative risk, 3.7; 95% confidence interval, 1.7-8.4) than for Caucasians (relative risk, 1.7; confidence interval, 0.8-2.3). Lower levels of recreational activity were weakly associated with increased prostate cancer risk among African-Americans but not among Caucasians. Prostate cancer risk was unrelated to a variety of anthropometric variables. These results suggest that inactive men are at increased risk of prostate cancer. (+info)
The role of dopamine D2 receptor in the behavioral effects of imipramine--study with the use of antisense oligonucleotides.
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Antisense strategies have a potential to specifically block the production of a given protein, e.g. receptor subtype, thus may help to uncover its behavioral and/or biochemical function. In the present study we demonstrated the utility of this approach for studying the role of dopamine D2 receptors in the anti-immobility effect of imipramine in the forced swimming test. Following intracerebroventricular (i.c.v.) administration of phosphorothioate oligonucleotide complementary to mRNA encoding for dopamine D2 receptors (D2 antisense ODN; 1 nmol/1 microl H2O, twice a day for 5 days) to the rats, the decrease in the locomotor activity (shortened total distance travelled and decrease in vertical activity, without differences in the stereotypic movements of animals), as well as the decrease of specific binding of [3H]raclopride in the striatum and limbic forebrain were observed. At the same time, i.c.v. administration of D2 antisense ODN reversed the effect of imipramine in the forced swimming test, what may indicate that the dopamine D2 receptors play a significant role in the behavioral anti-immobility effects of imipramine. (+info)
A modified Thompson quadricepsplasty for the stiff knee.
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Between March 1987 and March 1997, we performed a modified Thompson quadricepsplasty on 20 stiff knees and followed the patients for a mean of 35 months (24 to 52). After the operation, the knee was immobilised in flexion and periodically extended. At the final follow-up, the mean active flexion was 113.5 degrees (75 to 150). The final mean gain in movement was 67.6 degrees (5 to 105). One patient had a deep infection which resolved after wound care and intravenous antibiotics. The modified Thompson quadricepsplasty with appropriate postoperative care can give good results. (+info)
Immobilization stress induces c-Fos accumulation in liver.
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Acute stress-induced injury in tissues has been revealed by both biochemical markers in plasma and microscopy. However, little is known of the mechanisms by which tissue integrity is restored. Recently, induction of early response genes such as c-fos has been reported in the heart and stomach of immobilized animals. Herein, we show that immobilization stress in mice increased plasma alanine aminotransferase activity, a marker of liver damage. c-Fos protein accumulation in liver was induced by stress after 20 minutes of immobilization and persisted for 3 hours. Immobilization also induced the release of epidermal growth factor (EGF) from submandibular salivary glands and a transient increase in EGF concentration in plasma. Although EGF administration induced a 2.5-fold increase in c-Fos mass in the liver of anesthetized mice, sialoadenectomy (which abolished the effect of immobilization on plasma EGF) did not affect the stress-induced rise in plasma alanine aminotransferase activity or liver c-Fos accumulation. Therefore, we conclude that immobilization stress induces c-Fos accumulation in liver and that this effect is not triggered by the increase in plasma EGF concentration. (+info)