Effect of DHEA therapy on sexual behavior in female rats.

Delta-5 androgen therapies seem to enhance the sexual response in experimental animal models and in clinical trial. This study analyzed the influence of dehydroepiandrosterone (DHEA) administration on receptive and proceptive components of female rat sexual behavior. Ovariectomized (OVX) adult rats were divided in six groups submitted to the following treatments for 4 weeks: DHEA 0.5 and 5 mg/kg, by oral gavage, alone or in combination with estradiol benzoate 3 µg/rat; EB 3 and 10 µg/rat as control groups. All animals received progesterone (500 µg/rat) 4 h before the behavioral tests. All animals were tested for the following: receptivity and proceptivity weekly for 4 weeks; partner preference and paced mating behavior at the end of the treatments. Oral administration of DHEA at 5 mg/kg in EB primed rats was able to significantly increase proceptive behaviors, already after 1 week of treatment. The increase was more marked after 3 and 4 weeks of treatment. Behavioral changes were associated to modifications of circulating and brain level of allopregnanolone and beta-endorphin, although circulating hormonal levels were within a physiological range. Hormonal treatment using physiological doses of delta-5 androgens (DHEA) positively affects sexual motivation in OVX rats.

Increased sexual motivation in female rats treated with Humulus lupulus L. extract.

AIM OF THE STUDY: To evaluate the influence of Humulus lupulus extract on sexual behavior in female rats. MATERIALS AND METHODS: Ovariectomized rats hormonally primed with estradiol benzoate (1.5 µg/rat) and progesterone (500 µg/rat) were acutely treated by oral gavage with Humulus lupulus extract dosed at 5, 10 and 25mg/kg and then tested for partner preference and sexual receptivity. RESULTS: The administration of Humulus lupulus extract at the highest dose significantly increased the preference for the stimulus male during the partner preference test and the number of proceptive behaviors during the receptivity test, without affecting the lordosis response. CONCLUSIONS: Humulus lupulus extract increased sexual motivation in hormone-primed female rats.

Influence of ferutinin on bone metabolism in ovariectomized rats. II: role in recovering osteoporosis.

The aim of the present investigation, which represents an extension of a previous study, was to investigate the effect of ferutinin in recovering severe osteoporosis due to estrogen deficiency after rat ovariectomy and to compare phytoestrogen effects with those of estrogens commonly used in hormone replacement therapy (HRT) by women with postmenopausal osteoporosis. The animal model used was the Sprague-Dawley ovariectomized rat. Ferutinin was orally administered (2 mg kg(-1) per day) for 30 or 60 days starting from 2 months after ovariectomy (i.e. when osteoporosis was clearly evident) and its effects were compared with those of estradiol benzoate (1.5 microg per rat twice a week, subcutaneously injected) vs. vehicle-treated ovariectomized (OVX) and sham-operated (SHAM) rats. Histomorphometric analyses were performed on trabecular bone of lumbar vertebrae (4th and 5th) and distal femoral epiphysis, as well as on cortical bone of femoral diaphysis. Bone histomorphometric analyses showed that ferutinin seems to display the same effects on bone mass recorded with estradiol benzoate, thus suggesting that it could enhance the recovery of bone loss due to severe estrogen deficiency in OVX rats. On this basis, the authors propose listing ferutinin among the substances representing a potential alternative for the treatment of postmenopausal osteoporosis, which occurs as a result of estrogen deficiency.

Leptin increases growth of primary ossification centers in fetal mice.

The effect of peripheral leptin on fetal primary ossification centers during the early phases of bone histogenesis was investigated by administration of leptin to pregnant mice. Fourteen pregnant mice were divided into two groups. The treated pregnant group was subcutaneously injected in the intrascapular region with supraphysiologic doses (2 mg kg(-1)) of leptin (Vinci Biochem, Firenze, Italy) in a volume of 0.1 mL per 10 g body weight, at the 7th, 9th and 11th day of gestation. The control group was treated with physiological solution in the same manner and same times as the treated group. The new-born mice were killed 1 day after birth and the primary ossification centers were stained with Alizarin Red S after diaphanizing the soft tissues in 1% potassium hydroxide. The development of both endochondral and intramembranous ossification centers was morphometrically analysed in long bones. The results showed that the ossification centers of mice born by mothers treated with leptin grow more rapidly in both length and cross-sectional area compared with mice born by the untreated mothers. As the development of long bones depends on endochondral ossification occurring at proximal and distal epiphyseal plates as well as on intramembranous ossification along the periosteal surface, it appears that leptin activates the differentiation and proliferation of both chondrocytes and osteoblasts. The role of leptin as a growth factor of cartilage and bone is discussed in the light of the data reported in the literature.

Influence of ferutinin on bone metabolism in ovariectomized rats. I: role in preventing osteoporosis.

Phytoestrogens play a role in maintaining bone mass in the post-menopausal period for their putative function as osteoprotective agents. The aim of the present study was to investigate the influence of Ferutinin, a phytoestrogen found in the plants of Ferula genus, on bone loss in ovariectomized rats. Such an animal model can simulate the various clinical syndromes deriving from osteoporosis. The effect of the daily oral administration of ferutinin to ovariectomized rats (dosed at 2 mg/kg per day for 30 and 60 days) was compared to that of estradiol benzoate (subcutaneously administered at the dose of 1.5 microg/rat twice a week). After the sacrifice, histomorphometrical analyses were performed on trabecular bone of L4-L5 vertebrae and distal femoral metaphysis, as well as on cortical bone of femoral diaphysis; biochemical parameters (bone mineral components and markers) were also evaluated from the rat serum. The histomorphometrical analyses of trabecular and cortical bone from lumbar vertebrae and femur showed that ferutinin has the same antiosteoporotic effect of estradiol benzoate on bone mass, and in some cases is even stronger. This fact suggests that it could prevent osteoporosis caused by severe estrogen deficiency in ovariectomized rats. The possibility of using ferutinin as an alternative to the commonly employed hormonal replacing therapy in post-menopausal women is discussed.

Improved sexual behavior in male rats treated with a Chinese herbal extract: hormonal and neuronal implications.

AIM: To investigate the influence of an extract obtained from five Chinese medicinal plants on sexual behavior of adult male rats. METHODS: The extract was administered at doses of 30, 60 and 120 mg/kg by oral gavage, acutely (one time, 45 min before mating test) or subchronically (daily for 10 days) in sexually potent and sexually sluggish/impotent rats. Sexual behavior, serum levels of luteinizing hormone (LH) and testosterone (T) were evaluated in treated rats and compared with controls receiving vehicle. The effect of the extract on central dopaminergic neurotransmission was assessed in the nucleus accumbens using a microdialysis technique. RESULTS: In sexually potent rats, both acute and subchronic treatment with the extract dosed at 30 and 60 mg/kg reduced mount latency and intromission latency. In sluggish/impotent rats, the acutely administered extract at the dose of 60 mg/kg shortened ejaculation latency, whereas subchronically administered at the doses of 30 and 60 mg/kg, reduced mount, intromission and ejaculation latencies, increasing also the percentage of mounting and ejaculating rats. The extract dosed at 60 mg/kg significantly increased LH and T following acute and subchronic administration and increased 3,4-dihydroxyphenylacetic acid levels in the nucleus accumbens, 30 min after the acute administration. CONCLUSION: The improvement in both appetitive and consummatory components of sexual behavior observed in male rats treated with the extract could be ascribed to increased serum T level in parallel with the activation of the central dopaminergic system.

Influence of mirtazapine on the sexual behavior of male rats.

RATIONALE: 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-HT(2C) 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-HT(2C) receptors, which are involved in the negative influence of serotonin on male sexual behavior.