Microencapsulation of sunscreen reduces toxicity of its components to A. salina: Biochemical, behavioral and morphological studies.

Sunscreens contain several substances that cause damage to species where they are disposed. New formulations have been created to prevent such marine environmental damages. One promising formulation is the microencapsulated sunscreen. The objective of this study was to evaluate the possible safety to marine environment of one microencapsulated sunscreen formulation. The animal model Artemia salina (cists and nauplii) was tested with two sunscreen formulations (microencapsulated and non-microencapsulated) and toxicological, behavioral, morphological parameters as well as biochemical assays (lipoperoxidation and carbonylation tests) were analyzed. Results showed that microencapsulated sunscreen impeded some toxic effects caused by the release of the substances within the microcapsule in the highest concentration, reestablishing the mortality and hatching rates to control levels, while removing the sunscreen microcapsule by adding 1 % DMSO reduced the cyst hatching rate, increasing the nauplii mortality rate and decreased locomotor activity in higher concentrations. Finally, nauplii with 24 hours of life and exposed to sunscreen without the microcapsule showed an increase in mitochondrial activity (assessed at 48 hours after exposure) and presented malformations when exposed to the highest concentration non-microencapsulated concentration (assessed by SEM at 72 hours after exposure), when compared to the control group. These results together allow us to conclude that the microencapsulation process of a sunscreen helps protecting A. salina from the harmful effects of higher concentrations of said sunscreens. However, long-term studies must be carried out as it is not known how long a microencapsulated sunscreen can remain in the environment without causing harmful effects to the marine ecosystem and becoming an ecologically relevant pollutant.

Acute Lipopolysaccharide Switches the Selection of Maternal Behavior to Predatory Behavior in Female Rats.

OBJECTIVES: A common problem during the postpartum period and during lactation is being affected by infection due to Gram-negative bacteria. In this situation, a sick mother needs to choose between caring for her pups or the need for survival. This study analyzed the effects of lipopolysaccharide (LPS)-induced sickness behavior on selection between maternal behavior (MB) and predatory behavior (PB) in lactating rats. To assess the LPS-induced sickness behavior, the plasma tumor necrosis factor-α (TNF-α) levels were measured. METHODS: Lactating rats received 100 µg/kg LPS or saline solution on day 5 or 6 of lactation, 2 h before testing. Five pups and 5 cockroaches were introduced to the experimental cage at the same time and maternal and PB were observed for 30 min. The MB was measured by the pup contact, grouping, grooming, and kyphosis and the PB by contacting, eating, and foraging insects. General maternal activity was also observed, including exploration, self-grooming, and immobility. Immediately after the observations, blood was collected to measure the plasma TNF-α levels. RESULTS: LPS administration reduced the time and frequency of pup contact, grouping, grooming, and kyphosis, with an increase in the latency to first pup contact and grouping. With regard to PB, the time of foraging and eating insects increased, and the latencies to first insect contact, eating insects, and foraging decreased. With regard to general maternal activity, immobility time and TNF-α levels increased in the LPS-treated group. CONCLUSIONS: LPS exposure switched MB to PB, prioritizing maternal survival. Thus, in more favorable situations, these rats may have new offspring and therefore her species would survive for long.

Prenatal lipopolysaccharide exposure affects sexual dimorphism in different germlines of mice with a depressive phenotype.

The objective of the present study was to investigate whether prenatal lipopolysaccharide (LPS) administration modifies the expression of depressive and non-depressive-like behavior in male and female mice across two generations. The sexual dimorphism of these mice was also examined in the open-field test. Male and female mice of the parental (F0) generation were selected for depressive- or non-depressive-like behavioral profiles using the tail suspension test (TST). Animals with similar profiles were matched for further mating. On gestation day (GD) 15, pregnant F0 mice received LPS (100µg/kg, i.p.) and were allowed to nurture their offspring freely. Adult male and female of the F1 generation were then selected according to behavioral profiles and observed in the open field. Male and female mice of the two behavioral profiles were then mated to obtain the F2 generation. Adults from the F2 generation were also behaviorally phenotyped, and open field behavior was assessed. Male mice that were selected for depressive- and non-depressive-like behaviors and treated or not with LPS in the parental generation exhibited similar proportions of behavioral profiles in both filial lines, but LPS exposure increased the number of depressive-like behavior. An effect of gender was observed in the F1 and F2 generations, in which male mice were more sensitive to the intergenerational effects of LPS in the TST. These data indicate that prenatal LPS exposure on GD15 in the F0 generation influenced the transmission of depressive- and non-depressive-like behavior across filial lines, with sexual dimorphism between phenotypes.

Role of steroid hormones and morphine treatment in the modulation of opioid receptor gene expression in brain structures in the female rat.

This study determined the effects of acute treatment with morphine on the expression of the Oprm1, Oprk1, and Oprd1 genes (which encode µ, κ, and δ receptors, respectively) in the striatum, hypothalamus, and periaqueductal gray (PAG) in ovariectomized female rats treated with estrogen. Ovariectomized female rats were divided into five equal groups. Two groups received estrogen (50 µg/kg, 54 h before testing) and saline (ES group) or 3.5 mg/kg morphine (EM group) 2 h before euthanasia. The SS group received saline solution 54 and 2 h before the experiments. The SM group received saline 54 h and 3.5 mg/kg morphine 2 h before the experiments. The W group remained undisturbed. The genes expression were evaluated. Oprm1 and Oprk1 expression were activated, respectively, in the hypothalamus and PAG and in the striatum and PAG by morphine only in estrogen-treated animals. Oprd1 expression in the hypothalamus and PAG was activated by morphine in both estrogen-treated and -nontreated animals. The Oprm1 and Oprk1 gene response to morphine might depend on estrogen, whereas the Oprd1 gene response to morphine might not depend on estrogen, supporting the hypothesis of a functional role for ovarian hormones in opioid receptor-mediated functional adaptations in the female brain.

Lipopolysaccharide-induced sickness behavior in lactating rats decreases ultrasonic vocalizations and exacerbates immune system activity in male offspring.

OBJECTIVE: The present study analyzed the effects of lipopolysaccharide (LPS) on maternal behavior during lactation and possible correlations with changes in emotional and immune responses in offspring. METHODS: Lactating rats received 100 µg/kg LPS, and the control group received saline solution on lactation day (LD) 3. Maternal general activity and maternal behavior were observed on LD5 (i.e. the day that the peak of fever occurred). In male pups, hematological parameters and ultrasonic vocalizations (USVs) were assessed on LD5. At weaning, an additional dose of LPS (50 µg/kg, i.p.) was administered in male pups, and open-field behavior, oxidative burst and phagocytosis were evaluated. RESULTS: A reduction in the time in which dams retrieved the pups was observed, whereas no effects on maternal aggressive behavior were found. On LD5, a reduction of the frequency of USVs was observed in pups, but no signs of inflammation were found. At weaning, an increase in immune system activity was observed, but no differences in open-field behavior were found. CONCLUSION: These results indicate that inflammation in lactating mothers disrupted mother/pup interactions and may have produced short- and long-term effects on pup behavior as well as biological pathways that modulate inflammatory responses to bacterial endotoxin challenge in pups.

Prenatal lipopolysaccharide disrupts maternal behavior, reduces nest odor preference in pups, and induces anxiety: studies of F1 and F2 generations.

The present study analyzed the transgenerational effects of lipopolysaccharide (LPS; 100 µg/kg) administration on gestational day 18 (GD18) of parental generation on maternal-pups interaction of F1 and F2 generations. Also the long term behavioral effects were observed in male of F2 generation. In F1 generation, the reproductive performance, maternal behavior, maternal aggressive behavior, and general activity in the open field in adulthood were analyzed. In F2 generation, body weight at birth and at weaning, nest odor preference, and general activity in the open field and elevated plus maze in adulthood were assessed. Compared to controls, results showed that in the F1 generation, prenatal LPS exposure (1) increased the latency to full maternal behavior, but all of the females grouped the pups and presented full maternal behavior, (2) reduced the total time boxing and fighting, increased the frequency of retrieving the pups, and increased the number of bites, and (3) did not affect reproductive performance or general activity. In F2 generation, compared with controls, the LPS group exhibited (1) a decrease in body weight at weaning, (2) a decrease in nest odor preference, (3) a decrease in the percentage of time spent in the open arms, a decrease in the percentage of time spent in the center, and an increase in the time spent in the closed arms in the elevated plus maze, and (Huang et al.) no affect behavior in the open field. Prenatal LPS exposure improved maternal care in the F1 generation with regard to nursing and pup survival but did not improve the motivational parameters of maternal behavior likely because of a reduction of maternal stimulation by the pups. In the F2 generation, the reduction of nest odor preference in the pups suggests a less maternal recognition. In adulthood, these rats exhibited increased anxiety-like behavior. These data did not result from motor alterations because rats in both the F1 and F2 generations did not show alterations in open field behavior. This transfer of information across generations likely occurred through nongenetic means because the endotoxin was administered at the end of pregnancy. These results may have implications for clinical therapeutics in human disorders and evolution.

Physical exercise and vascular endothelial growth factor (VEGF) in elderly: A systematic review.

UNLABELLED: The aim of this study was to conduct a systematic review of studies that verified the effects of physical exercise on vascular endothelial growth factor (VEGF) in elderly. METHODOLOGY: The bibliographic search was conducted in five database, from 1990 to 2013, with the following keywords and boolean operators: physical exercise OR physical exercise OR physical therapy OR exercise OR training AND VEGF OR vascular endothelial growth factor AND aged OR older OR elderly. The inclusion criteria were: (1) sample including elderly with average age of 60; (2) studies that verified the effects of acute exercise; (3) studies that verified the effects of chronic physical exercise; (4) studies with humans; (5) randomized controlled trials, randomized non-controlled trials, non-randomized controlled trials, non-randomized and non-controlled trials; (6) assessment of VEGF peripheral concentrations. RESULTS: Ten studies were selected, and that four of them verified an increase of VEGF concentrations after practicing physical exercise and six studies did not verify any change on VEGF concentrations. CONCLUSION: Different populations found in this study and the different exercise protocols applied in the studies of this review make it difficult to establish parameters of what would be the best type of exercise to promote an increase on the concentrations of VEGF in the elderly. Therefore, we suggest that further studies can be performed, so that we can establish some recommendations for this population.

Acute aerobic exercise increases brain-derived neurotrophic factor levels in elderly with Alzheimer's disease.

Studies indicate the involvement of brain-derived neurotrophic factor (BDNF) in the pathogenesis of Alzheimer's disease (AD). Decreased BDNF levels may constitute a lack of trophic support and contribute to cognitive impairment in AD. The benefits of acute and chronic physical exercise on BDNF levels are well-documented in humans, however, exercise effects on BDNF levels have not been analyzed in older adults with AD. The aim of this study was to investigate the effects of acute aerobic exercise on BDNF levels in older adults with AD and to verify associations among BDNF levels, aerobic fitness, and level of physical activity. Using a controlled design, twenty-one patients with AD (76.3 ± 6.2 years) and eighteen healthy older adults (74.6 ± 4.7 years) completed an acute aerobic exercise. The outcomes included measures of BDNF plasma levels, aerobic fitness (treadmill grade, time to exhaustion, VO2, and maximal lactate) and level of physical activity (Baecke Questionnaire Modified for the Elderly). The independent t-test shows differences between groups with respect to the BDNF plasma levels at baseline (p = 0.04; t = 4.53; df = 37). In two-way ANOVA, a significant effect of time was found (p = 0.001; F = 13.63; df = 37), the aerobic exercise significantly increased BDNF plasma levels in AD patients and healthy controls. A significant correlation (p = 0.04; r = 0.33) was found between BDNF levels and the level of physical activity. The results of our study suggest that aerobic exercise increases BDNF plasma levels in patients with AD and healthy controls. In addition to that, BDNF levels had association with level of physical activity.

Enhancement of behavioral sensitization, anxiety-like behavior, and hippocampal and frontal cortical CREB levels following cocaine abstinence in mice exposed to cocaine during adolescence.

Adolescence has been linked to greater risk-taking and novelty-seeking behavior and a higher prevalence of drug abuse and risk of relapse. Decreases in cyclic adenosine monophosphate response element binding protein (CREB) and phosphorylated CREB (pCREB) have been reported after repeated cocaine administration in animal models. We compared the behavioral effects of cocaine and abstinence in adolescent and adult mice and investigated possible age-related differences in CREB and pCREB levels. Adolescent and adult male Swiss mice received one daily injection of saline or cocaine (10 mg/kg, i.p.) for 8 days. On day 9, the mice received a saline injection to evaluate possible environmental conditioning. After 9 days of withdrawal, the mice were tested in the elevated plus maze to evaluate anxiety-like behavior. Twelve days after the last saline/cocaine injection, the mice received a challenge injection of either cocaine or saline, and locomotor activity was assessed. One hour after the last injection, the brains were extracted, and CREB and pCREB levels were evaluated using Western blot in the prefrontal cortex (PFC) and hippocampus. The cocaine-pretreated mice during adolescence exhibited a greater magnitude of the expression of behavioral sensitization and greater cocaine withdrawal-induced anxiety-like behavior compared with the control group. Significant increases in CREB levels in the PFC and hippocampus and pCREB in the hippocampus were observed in cocaine-abstinent animals compared with the animals treated with cocaine in adulthood. Interestingly, significant negative correlations were observed between cocaine sensitization and CREB levels in both regions. These results suggest that the behavioral and neurochemical consequences of psychoactive substances in a still-developing nervous system can be more severe than in an already mature nervous system.

Maternal treatment with picrotoxin in late pregnancy improved female sexual behavior but did not alter male sexual behavior of offspring.

Previous studies from our laboratory investigated the effects of picrotoxin (PT), a γ-aminobutyric acid receptor antagonist administered during several perinatal periods, on the sexual behavior of male and female rats. We observed that the time of perinatal exposure to PT is critical to determine either facilitation or impairment of sexual behavior. The present study evaluated the effects of prenatal administration of a single dose of PT on gestation day 18 of dams (the first critical period of male brain sexual differentiation) on sexual behavior of male and female offspring. Thus, female Wistar rats were mated with males and, on gestation day 18, received 0.6 mg/kg of PT or 0.9% saline solution subcutaneously. On postnatal day 1, the offspring were weighed and several measures of sexual development were assessed. The sexual behaviors and the general activity in the open field of adult male and ovariectomized, hormone-treated female rats were observed. On comparison with the control group, maternal PT treatment: (i) did not alter the maternal weight, pup weight, anogenital distance, or male and female general activity; (ii) increased female sexual behavior, that is, decreased the latencies to first mount, first lordosis, and tenth lordosis, and the percentage of females presenting lordosis; and (iii) did not alter male sexual behavior. It is suggested that prenatal PT exposure interfered with epigenetic mechanisms related to the development of sex differences in the brain, leading to the observed sexually dimorphic effects on sexual behavior.

Maternal exposure to picrotoxin modifies the response of the GABAA receptor during sexual behavior of adult male rat offspring.

This study investigated whether perinatal exposure to picrotoxin, a GABAA antagonist, modifies the effect of muscimol, a GABAA agonist, on the sexual behavior of adult male rats. Two hours after birth and then once daily during the next 9 days of lactation, dams received picrotoxin (0.75 mg/kg subcutaneously) or saline (1 ml/kg subcutaneously). The adult male offspring from the picrotoxin and saline groups received saline (1 ml/kg intraperitoneally) or muscimol (1 mg/kg intraperitoneally), and 15 min later, their sexual behavior was assessed. Muscimol treatment in the saline-exposed group increased the mount and intromission latencies. However, these effects were absent in the picrotoxin-exposed groups. The latencies to first ejaculation, postejaculatory mount, and intromission were decreased in both picrotoxin-exposed groups relative to the saline-exposed groups. The picrotoxin+muscimol-treated rats required more intromissions to ejaculate and the picrotoxin-exposed groups made more ejaculations than the saline-exposed groups. Thus, muscimol treatment did not increase the mount and intromission latencies following picrotoxin exposure, but increased the ejaculation frequency, which did not differ between the picrotoxin+muscimol and the picrotoxin+saline groups. These data indicate that perinatal picrotoxin treatment interfered with GABAA receptor development.

Plasticity of opioid receptors in the female periaqueductal gray: multiparity-induced increase in the activity of genes encoding for mu and kappa receptors and a post-translational decrease in delta receptor expression.

The periaqueductal gray (PAG) has been reported as a potential site for opioid regulation of behavioral selection. Opioid-mediated behavioral and physiological responses differ between nulliparous and multiparous females. This study addresses the effects of multiple reproductive experiences on µ-, κ- and δ-opioid receptor (Oprm1, Oprk1, and Oprd1 respectively) gene activity and µ, κ and δ protein expression (MOR, KOR and DOR respectively) in the PAG of the female rats. This was done by evaluating the opioid gene expression using real-time (RT-PCR) and quantification of each protein receptor by Western blot analysis. The RT-PCR results show that multiple reproductive experiences increase Oprm1 and Oprk1 gene expression. Western blot analysis revealed increased MOR and KOR while DOR protein was decreased in multiparous animals. Taken together, these data suggest that multiple reproductive experiences influence both gene activity and opioid receptor expression in the PAG. Post-translational mechanisms seem particularly relevant for DOR expression. Thus, opioid transmission in the PAG might be modulated by different mechanisms of multiparity-induced plasticity according to the opioid receptor type.

Ethanol-induced sensitization depends preferentially on D1 rather than D2 dopamine receptors.

Behavioral sensitization, defined as a progressive increase in the locomotor stimulant effects elicited by repeated exposure to drugs of abuse, has been used as an animal model for drug craving in humans. The mesoaccumbens dopaminergic system has been proposed to be critically involved in this phenomenon; however, few studies have been designed to systematically investigate the effects of dopaminergic antagonists on development and expression of behavioral sensitization to ethanol in Swiss mice. We first tested the effects of D(1) antagonist SCH-23390 (0-0.03 mg/kg) or D(2) antagonist Sulpiride (0-30 mg/kg) on the locomotor responses to an acute injection of ethanol (2.0 g/kg). Results showed that all tested doses of the antagonists were effective in blocking ethanol's stimulant effects. In another set of experiments, mice were pretreated intraperitoneally with SCH-23390 (0.01 mg/kg) or Sulpiride (10 mg/kg) 30 min before saline or ethanol injection, for 21 days. Locomotor activity was measured weekly for 20 min. Four days following this pretreatment, all mice were challenged with ethanol. Both antagonists attenuated the development of ethanol sensitization, but only SCH-23390 blocked the expression of ethanol sensitization according to this protocol. When we tested a single dose (30 min before tests) of either antagonist in mice treated chronically with ethanol, both antagonists attenuated ethanol-induced effects. The present findings demonstrate that the concomitant administration of ethanol with D(1) but not D(2) antagonist prevented the expression of ethanol sensitization, suggesting that the neuroadaptations underlying ethanol behavioral sensitization depend preferentially on D(1) receptor actions.

Prenatal lipopolysaccharide exposure affects maternal behavior and male offspring sexual behavior in adulthood.

OBJECTIVE: This study investigates the effects of prenatal lipopolysaccharide (LPS) exposure on the maternal behavior of pregnant rats and the physical development and sexual behavior of their male offspring in adulthood. METHODS: For two experiments, pregnant rats were injected with LPS (250 microg/kg, i.p.) on gestation day (GD) 21. In the first experiment, the maternal behavior (postnatal day, PND, 6) and the dam's open-field general activity (PND7) were evaluated. In the second experiment, the maternal pre- and postnatal parameters, the pup's development, the offspring's sexual behavior in adulthood, and the pup's organ weights were assessed. RESULTS: Compared to the control group, the LPS-treated dams presented reduced maternal behavior, decreased general activity, a smaller body weight difference between GD21 and PND1, a greater number of perinatal deaths, and smaller litters. For the male pups, LPS treatment resulted in a decreased body weight on PND2, whereas the anogenital distance and the day of testis descent were not modified. The male sexual behavior was impaired by prenatal LPS. Particularly the number of ejaculating animals was reduced. The testis weight was also lower in the prenatally LPS-treated rats than in the control rats. CONCLUSION: We propose that prenatal LPS exposure on GD21 acts as an imprinting factor that interferes with the programming of brain sexual determination in offspring.

Sexual experience did not affect the long-term sexual behavior inhibition of male rats treated with fluoxetine

Antidepressants, including tricyclics, monoamine oxidase inhibitors and selective serotonin reuptake inhibitors cause sexual dysfunctions such as decreased sexual desire, erectile difficulties, and delayed ejaculation. Studies have shown that treatment with fluoxetine inhibits several components of sexual behavior in male rats. It is known that sexual experience improves the sexual behavior of male rats. Thus, the effects of sexual experience were examined in male rats during long-term treatment with fluoxetine or vehicle. Rats treated with 10mg/kg fluoxetine or vehicle daily (28 days) were observed for sexual behavior at the 14th, 21st, and 28th day of treatment. Long-term administration of fluoxetine increased the mount latency in control rats in the first session; no differences were observed in other parameters on the same day. Still in the control group, the mount and intromission latencies gradually decreased, whereas the number of intromissions and ejaculations increased over the sessions. The group in long-term treatment with fluoxetine also showed reduced mount and intromission latencies, although latencies remained significantly higher as compared to the control group. Fluoxetine-treated rats showed increased mount and intromission rates on the 28th day of treatment in relation to the first day. These data suggest that the impairment caused by long-term treatment with fluoxetine persists throughout the sessions despite the rats’ sexual experience.(AU)

Sexual experience did not affect the long-term sexual behavior inhibition of male rats treated with fluoxetine

Antidepressants, including tricyclics, monoamine oxidase inhibitors and selective serotonin reuptake inhibitors cause sexual dysfunctions such as decreased sexual desire, erectile difficulties, and delayed ejaculation. Studies have shown that treatment with fluoxetine inhibits several components of sexual behavior in male rats. It is known that sexual experience improves the sexual behavior of male rats. Thus, the effects of sexual experience were examined in male rats during long-term treatment with fluoxetine or vehicle. Rats treated with 10mg/kg fluoxetine or vehicle daily (28 days) were observed for sexual behavior at the 14th, 21st, and 28th day of treatment. Long-term administration of fluoxetine increased the mount latency in control rats in the first session; no differences were observed in other parameters on the same day. Still in the control group, the mount and intromission latencies gradually decreased, whereas the number of intromissions and ejaculations increased over the sessions. The group in long-term treatment with fluoxetine also showed reduced mount and intromission latencies, although latencies remained significantly higher as compared to the control group. Fluoxetine-treated rats showed increased mount and intromission rates on the 28th day of treatment in relation to the first day. These data suggest that the impairment caused by long-term treatment with fluoxetine persists throughout the sessions despite the rats’ sexual experience.

Behavioral effects of acute stimulation of kappa-opioid receptors during lactation.

The behavioral effects of the kappa-opioid receptor agonist U69593 were examined in lactating rats. On day 5 of lactation, animals were treated with 0.1 mg/kg of U69593 to determine whether it influences general activity and maternal latencies toward pups. Because little attention has been given to the possibility that pre-mating treatment with morphine may modulate the response to kappa-opioid receptor stimulation, another group of animals was submitted to the same acute challenge after abrupt withdrawal from repeated treatment with morphine sulfate during the pre-mating period (5 mg/kg on alternate days for a total of five doses). Acute kappa-opioid stimulation reduced total locomotion, rearing frequency, and time spent self-grooming and increased immobility duration. These kappa agonist effects were not observed in animals pretreated with morphine. Similarly, latencies to retrieve pups were longer only in animals pretreated with saline and challenged acutely with U69593. None of these effects were observed in morphine sulfate-pretreated animals. The present results suggest that pre-mating repeated exposure to morphine produces a tolerance-like effect on behavioral responses to low-dose kappa-opioid receptor stimulation in active reproductive females.

The effect of hetero- and homosexual experience and long-term treatment with fluoxetine on homosexual behavior in male rats.

INTRODUCTION: The selective serotonin reuptake inhibitors have become the most frequently prescribed drugs for the treatment of depression. Sexual side effects have been noted to occur with this treatment on heterosexual behavior in rats. Heterosexual experience facilitates sexual orientation of male rats and decreases the latencies to first mount and first intromission. On the other hand, homosexual behavior in male rats induced by female hormones has not been evaluated. AIM: The objective of this work is to evaluate the effects of heterosexual and homosexual experience in male rats long-term treated with fluoxetine (FLX) on homosexual hormone-induced behavior. MATERIALS AND METHODS: Male rats were treated with FLX or saline solution (10 mg/kg for 65 days). At days 36, 50, and 65 of the treatment, the rats were evaluated for homosexual behavior. Other rats treated with FLX or saline solution for 60 consecutive days were submitted to heterosexual behavior at 14, 21, and 28 days of the treatment. After this, they were orquiectomized and homosexual hormone-induced behavior was observed at 45 and 60 days of the treatment. RESULTS: (1) Only treatment with FLX did not affect the homosexual behavior. (2) The homosexual experience facilitated the homosexual behavior mainly on the animals from the control group. (3) The heterosexual experience facilitated the homosexual behavior on both groups. CONCLUSIONS: Only long-term administration of FLX does not interfere with the homosexual behavior in male rats. The homosexual and the heterosexual experience facilitated the homosexual behavior on the control and experimental groups. We suggested that learning aspects related to sexual behavior are responsible by these results.

Effects of perinatal picrotoxin and sexual experience on heterosexual and homosexual behavior in male rats.

The effects of perinatal picrotoxin (0.75 mg/kg) on heterosexual and homosexual behavior of male rats, sexually experienced or not, were studied. The following data were obtained: (1) at birth, body weight and anogenital distance were not modified by the treatment; (2) during lactation, both treatment and sex interfered with body weight as well as in adult age; (3) as experimental animals were trained, the heterosexual behavior was improved; (4) picrotoxin treatment reduced lordotic response of homosexual behavior in inexperienced male rats and (5) the heterosexual experience with female rats inhibited homosexual behavior of both experimental and control animals. These results suggest that perinatal maternal picrotoxin exposure improved heterosexual behavior in male rats and the sexual experience reveals this effect. In addition, picrotoxin did not induce feminization in experimental inexperienced rats. Finally, the sexual experience per se promotes changes in brain regions related to male behavioral and sexual aspects.