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Influence of S-adenosyl-L-methionine on chronic mild stress-induced anhedonia in castrated rats
No full text1 S-adenosyl-L-methionine (SAMe) is the most important methyl donor in the brain and is essential for polyamine synthesis. Methyl group deficiency in the brain has been implicated in depression; on the other hand, polyamines enhance phosphorylation processes, and phosphorylation of functional proteins in neurons is involved in the therapeutic mechanisms of antidepressants. 2 The effect of SAMe in an animal model of 'depression', the chronic mild stress-induced anhedonia, was studied using long-term castrated male and female Lister hooded rats. 3 Chronic daily exposure to an unpredictable sequence of mild stressors produced, within 3 weeks, a significant reduction of the consumption of a sucrose solution. SAMe (100, 200 or 300 mg kg(-1) daily i.m.) while having no influence on sucrose intake in non-stressed animals, dose-dependently reinstated sucrose consumption within the first week of treatment, both in male and in female stressed rats. Imipramine (10 mg kg(-1) daily i.p.) produced a similar effect after a 3 week treatment. 4 Similarly, a palatable food reward-induced place preference conditioning was developed in SAMe (200 or 300 mg kg(-1) daily i.m.)- and in imipramine (10 mg kg(-1) daily i.p.)-treated chronically stressed animals (males and females), whilst it could not be obtained in vehicle-treated rats. 5 Moreover, the same doses of SAMe (but not of imipramine) restored the exploratory activity and curiosity for the environment (rearing), in the open-field test. 6 While imipramine caused a blockade of the growth throughout the treatment, SAMe produced only a transient growth arrest during the first week of treatment. 7 These results show that SAMe reverses an experimental condition of 'depression-like' behaviour in rats, the effect being more rapid and complete than that of imipramine, and without apparent side effects
Behavioral and developmental outcomes of prenatal and postnatal vanadium exposure in the rat
No full textThe developmental and behavioral outcomes of uninterrupted exposure to vanadium was studied in the rat. Starting 3 days before birth and up to the 100th day of extrauterine life, rats received as drink either a water solution of vanadyl sulphate (300 mg l(-1) containing 70 mg l(-1) of vanadium element, which is equal to an ingested dose of about 10 mg kg(-1) per day of vanadium element) plus NaCl 5 g l(-1), or a water solution of NaCl 5 g l(-1), or plain water [up to weaning (25th day of extrauterine life) treatment was given to dams and offspring]. At M weaning, survivors were fewer and body weight was found to be significantly lower in the offspring of vanadium plus NaCl-treated dams than in the offspring of the other two groups. After weaning, growth retardation continued to be significant in both vanadium plus NaCl- and NaCl-treated rats. Such an effect was more pronounced in males than in females. Locomotor activity-evaluated at 1 month of; age-was not significantly different in the three groups of rats. In the open-field, male (but not female) vanadium plus NaCl-treated rats had a reduced outer ambulation, rearing posture and grooming activity, and an increased defecation, in comparison with the males of the NaCl group, and reduced rearing in comparison with control males. As concerns ingestive behaviors, the only significant datum was an increased water intake in NaCl-treated males. Finally, at the 100th day of life, working memory was significantly impaired in both vanadium plus NaCl- and NaCl-treated rats
Influence of mirtazapine on the sexual behavior of male rats
No full textRationale. Impairment of sexual activity is one of the most frequent side effects of antidepressant drugs. The increase in the synaptic concentrations of serotonin seems to be mainly responsible. Mirtazapine is a novel antidepressant that increases the synaptic concentrations of both noradrenaline and serotonin; moreover, it is an antagonist at 5-HT2C receptors, whose activation is considered to be responsible for some typical effects of serotonin on the ejaculation process (retardation of ejaculation, anorgasmia).Objectives. To study the influence of mirtazapine on copulatory performance and sexual motivation in male rats, in comparison-or in combination-with fluoxetine. Methods. Copulatory performance was studied either in sexually experienced or in sexually naive rats; sexual motivation was studied in sexually experienced rats. Mirtazapine (1, 5 or 10 mg/kg), fluoxetine (10 mg/kg), and the combination of mirtazapine + fluoxetine (10+10 mg/kg) were subcutaneously (s.c.) administered either acutely or daily for 13 days. Results. After acute administration, mirtazapine decreased mount latency (ML) and intromission latency (IL), and increased mount frequency (MF) and ejaculation latency (EL). Fluoxetine had no significant effect on any of the sexual behavior parameters. After a 13-day treatment, mirtazapine increased ML, IL and MF; fluoxetine increased ML, IL and the intercopulatory interval (ICI); the addition of mirtazapine to fluoxetine produced a reduction of ICI and an increase of MF. Moreover, mirtazapine significantly improved the performance of rats in the sexual motivation test. Conclusions. The present results show that, on the whole, the acute administration of mirtazapine improves several parameters of the copulatory performance of male rats and strongly stimulates sexual motivation, while the repeated administration produces minor, conflicting effects. This effect of mirtazapine on male rat sexual behavior is to be ascribed to the antagonism at brain alpha(2) adrenergic auto- and hetero-receptors, with consequent increased release of noradrenaline and serotonin, and antagonism at 5-HT2C receptors, which are involved in the negative influence of serotonin on male sexual behavior
The phytoestrogen ferutinin improves sexual behavior in ovariectomized rats
No full textThe present study was designed to examine the effect of ferutinin chronic administration on sexual behavior of ovariectomized non-estrogen-primed rats. Starting from 3 weeks after ovariectomy, female rats were orally treated with ferutinin at the doses of 0.2 and 0.5mg/kg, daily for 4 weeks. Ferutinin's effect was compared with that of estradiol benzoate, subcutaneously injected at the dose of 1.5mug/rat twice a week. Animals were tested for sexual motivation, receptivity and proceptivity after 1, 2 and 3 weeks of treatment and for paced mating behavior after 4 weeks of treatment. Before each experimental test, they received progesterone injection (500mug/rat). Both dosages of ferutinin significantly increased the receptive behavior in a time-dependent manner, as well as estradiol benzoate did. Also proceptive behaviors increased in ferutinin-treated animals in comparison with control ones. During the partner preference test ferutinin was able to induce a significant preference for a sexually active male over a sexually receptive female. Moreover, ferutinin restored a normal paced mating behavior, which had been suppressed by ovariectomy. These results show that ferutinin exerts an estrogenic activity in ovariectomized non-estrogen-primed female rats
Pharmacological manipulation of brain galaninergic system and sexual behavior in male mice
No full textAvailable data suggest a complex role for the brain galaninergic system in male sexual behavior; however, the results so far obtained in animals with either galanin or galanin antagonists are conflicting. Objective: To define the better influence of galanin on male sexual behavior by studying, in mice, (i) the effect of galanin and of the chimeric galanin peptide M40 on the copulatory performance, and (ii) galanin mRNA levels in hypothalamic arcuate and dorso-medial nuclei. Methods: For the behavioral testing, only sexually sluggish male mice were used. Galanin mRNA levels were studied in both sexually potent and impotent mice by means of in situ hybridization. Standard behavioral parameters for sexual behavior were recorded or calculated. Synthetic galanin (0.05, 0.1 or 1 mug/mouse) and M40 (5 or 20 mug/mouse) were intracerebroventricularly (ICV) injected, 15 min before the copulatory test. Galanin mRNA levels were evaluated. Results: In sexually sluggish male mice, both galanin (0.1 and 1 mug/mouse ICV) and M40 (20 mug/mouse ICV), significantly increased intromission frequency and ejaculation latency; M40 also improved copulatory efficacy. On the other hand, in the hypothalamic arcuate and dorso-medial nuclei, the levels of galanin mRNA were not significantly different in sexually potent and impotent male mice. Conclusions.-These results show that in sexually sluggish male mice the ICV injection of either galanin or the chimeric analogue M40 greatly prolongs the duration of the copulation; without a reduction of the sexual drive or of the copulatory performance. On the other hand, the hybridization experiments seem to rule out an important physiological role of the brain galaninergic system in the regulation of male sexual behavior, at least in mice
Improved sexual behavior in male rats treated with a Chinese herbal extract: hormonal and neuronal implications
Full text linkAim: To investigate the influence of an extract obtained from five Chinese medicinal plants on sexual behavior ofadult male rats. Methods: The extract was administered at doses of 30, 60 and 120 mg/kg by oral gavage, acutely (onetime, 45 min before mating test) or subchronically (daily for 10 days) in sexually potent and sexually sluggish/impotentrats. Sexual behavior, serum levels of luteinizing hormone (LH) and testosterone (T) were evaluated in treatedrats and compared with controls receiving vehicle. The effect of the extract on central dopaminergic neurotransmissionwas assessed in the nucleus accumbens using a microdialysis technique. Results: In sexually potent rats, bothacute and subchronic treatment with the extract dosed at 30 and 60 mg/kg reduced mount latency and intromissionlatency. In sluggish/impotent rats, the acutely administered extract at the dose of 60 mg/kg shortened ejaculationlatency, whereas subchronically administered at the doses of 30 and 60 mg/kg, reduced mount, intromission andejaculation latencies, increasing also the percentage of mounting and ejaculating rats. The extract dosed at 60 mg/kgsignificantly increased LH and T following acute and subchronic administration and increased 3,4-dihydroxyphenylaceticacid levels in the nucleus accumbens, 30 min after the acute administration. Conclusion: The improvement in bothappetitive and consummatory components of sexual behavior observed in male rats treated with the extract could beascribed to increased serum T level in parallel with the activation of the central dopaminergic system
Influence of estrogens and oxytocin on germ cells death in the neonatal mammalian ovary
No full textDuring mammalian oogenesis, some processes involve proliferation and others drastic reduction of germ cells. This study reports on the role played by two hormones, estradiol monobenzoate and oxytocin, in the control of the number of germ cells in the neonatal mouse ovary. Female neonatal mice were treated with doses ranging between 0.1 and 1 microg/mouse of estradiol monobenzoate or oxytocin and sacrificed at 5 days of postnatal age. The results showed that in the animals treated with estrogen, follicular development was more advanced than that of controls. Further the number of germ cells in apoptosis was drastically reduced. In the animals treated with oxytocin, the follicular development was arrested at the stage of primary follicles. In addition, the number of apoptotic germ cells increased if compared with that of the controls
Effects of estrogens and oxytocin on the development of neonatal mammalian ovary
No full textThe preservation and death of germ cells in the neonatal mammalian ovary are linked with the presence of hormones. Estrogens and oxytocin are present at birth in all mammalian vertebrates. The aim of this study was to examine their role in the development of the neonatal ovary and also in the preservation and death of germ cells in the neonatal period: apoptotic phenomena play a fundamental role in the control of their number. Female neonatal mice were treated at birth with estradiol monobenzoate or oxytocin and sacrificed after 5 days. The ovaries were sectioned in toto into semi-thin sections, in order to calculate their volume. Thin sections were also carried out to verify, under the transmission electron microscope (T.E.M.), the cells in apoptosis. The ovaries treated with the greater concentration of estradiol monobenzoate showed a volume that was significantly greater than that of the controls and a reduction of germ cells in apoptosis. The ovaries treated with oxytocin at all degrees of concentration had a volume significantly less than the controls and they also had a higher number of germ cells in apoptosis
Effect of ACTH-(1-24) on the volume of circulating blood and on regional blood flow in rats bled to hypovolemic shock.
No full textThese data show that the anti-shcok effect of ACTH-(1-24) in bleed rats is associated a massive increse in the volume of circulating blood and with a restoration of the venous blood flow in periferal vascular beds
Griffonia simplicifolia negatively affects sexual behavior in female rats
No full textAt present Griffonia simplicifolia is used in food supplement aimed to treat mood disorders as well asto reduce food intake and body weight. The plant has gained increasing interest for its high content in5-hydroxy-l-tryptophan (5-HTP) particularly in the seed. The present study was designed to evaluatethe influence of a seed extract of the plant, dosed at 25, 50 and 100 mg/kg, on the sexual behavior ofovariectomized hormone-primed rats after acute and subchronic treatment. The single administrationof G. simplicifolia significantly reduced lordosis response and increased rejection behavior in female ratstreated with the highest dose while it did not influence proceptive behaviors. On the other hand the subchronicadministration of the extract significantly reduced proceptivity but not receptivity, and increasedrejection behavior. All the tested dosages were able to markedly decrease food intake and body weightafter a 9-day treatment. Taken together the present results, possibly ascribed to increased levels of 5-hydroxytryptamine (5-HT) in the brain, suggest a cautious administration of the plant extract owing toits negative influence on female sexual behavior
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