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.

Repeated forced swim stress has additive effects in anxiety behavior and in cathecolamine levels of adult rats exposed to deltamethrin.

Deltamethrin (DTM) is a type II pyrethroid insecticide that elicits autonomic and neuroendocrine responses that indicate high levels of stress, presumably caused by the neurotoxic effect of the insecticide. This study investigated the effect of DTM exposure (10 mg/kg, p.o.) and an additional stress induced in the forced swim test (FST) in behavioral tasks related to anxiety, serum corticosterone levels, and striatal neurotransmitter levels. Open field behavior and social interaction were evaluated after DTM administration (10 mg kg(-1), p.o). DTM per se reduced rearing frequency in the open field, but no alterations in locomotion frequency or immobility duration were detected. Stress increased immobility duration compared with non-stressed animals. DTM reduced social interaction and increased corticosterone levels, and these effects were enhanced in stressed animals. Mainly stress affected dopaminergic and serotoninergic activity. In anxiety behavior and in both neurotransmitters and metabolites levels it was observed an additive effect of stress in DTM treated rat data. These results indicate that DTM enhanced the anxiogenic responses and stress had an additive effect over the DTM stress. The neurochemical data did not indicate an interaction between stress and DTM exposure. The present results maybe important for implementing pyrethroid insecticide safety standards.

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.