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Effect of dietary linoleate/alpha-linolenate balance on the brain lipid composition, reproductive outcome and behavior of rats during their prenatal and postnatal development.

The effect of the dietary linoleate (LA)/alpha-linolenate (LNA) balance during development on the brain lipid composition, reproductive outcome and behavior of rats was studied. Female rats were fed on experimental diets during pregnancy and the resulting pups for 16 weeks. The dietary LA/LNA ratios were 1.07 (LA1), 2.64 (LA2), 4.45 (LA3), 7.68 (LA4) and 10.35 (LA5). The relative content of docosahexaenoate (DHA) in the brain of pups tended to increase with decreasing LA/LNA ratio at 0 and 3 weeks, while the level of DHA was maintained constant at 16 weeks regardless of the dietary LA/LNA ratio. The learning ability was measured at 12 weeks of age, and there was no difference among the groups. In an open field test, the exploratory index was significantly lower in the LA1 group than in the LA2 group. The LA1 group had a smaller litter size and lower survival rate than the other groups. We conclude that if the diet contained appropriate amounts and balance of LA and LNA, it was possible for rats to synthesize an appropriate amount of DHA and have normal behavioral activity without DHA supplementation.

Animals↗

Effects of thymectomy on reproductive function and behavior.

The effects of thymectomy in perinatal Long-Evans rat pups on their reproductive function in early adulthood were examined. Thymectomized females had decreased lordotic responsivity to estrogen, while thymectomized males exhibited differences in mount latency or postejaculatory interval; these results suggest a possible influence of the thymus on the normal development of the neural substrates of sexual behavior. Gonadal histology appeared unperturbed in rats of either sex. No statistical abnormalities in luteinizing hormone or testosterone levels were seen in male animals. Likewise, no disturbances were observed in the ability of females to exhibit normal positive feedback after estrogen and progesterone administration; negative feedback after unilateral ovariectomy (as judged by ovarian compensatory hypertrophy) was also normal. The timing of puberty was not statistically delayed in females, even though slowed growth rates were observed. A heightened surgical stress response, as judged by progesterone levels in experimental females, suggests that perinatal thymectomy may possibly alter the sensitivity of adults to stress.

Animals↗

Perinatal exposure to genistein alters reproductive development and aggressive behavior in male mice.

Exposure to endocrine disrupting chemicals adversely affects reproductive development and behavior in males. The goal of this study was to determine if exposure to genistein, an isoflavone found in soy, during early periods of sex differentiation alters reproductive development and behavior in male mice. Female C57BL/6 mice were fed a phytoestrogen-free diet supplemented with 0, 5 or 300 mg/kg of genistein throughout gestation and lactation. Anogenital distance (AGD) and body mass of male offspring was measured weekly from postnatal days 2-21, timing of preputial separation was assessed at puberty, and in adulthood, reproductive organ masses, sperm and testosterone production, and reproductive and aggressive behaviors were assessed. Exposure to genistein resulted in smaller AGD are reduced body mass, with the low-dose diet exerting a greater effect. Timing of preputial separation, adult reproductive behavior, sperm concentrations and testosterone production were not influenced by genistein treatment at either dose. Aggressive behaviors were decreased, whereas defensive behaviors were increased, in males that received the low-dose genistein diet. Exposure to genistein during critical periods of sex differentiation results in concurrent and persistent demasculinization in male mice. Phenotypic and behavioral abnormalities induced by genistein showed a non-monotonic response, where treatment with a low dose exerted a greater effect than treatment with a high dose of genistein. Given the popularity of soy infant formulas, the influence isoflavone exposure on reproductive and behavioral health in boys and men should be considered.

Administration, Oral↗

Juvenile hormone, reproduction, and worker behavior in the neotropical social wasp Polistes canadensis.

Previous studies of the division of labor in colonies of eusocial Hymenoptera (wasps and bees) have led to two hypotheses regarding the evolution of juvenile hormone (JH) involvement. The novel- or single-function hypothesis proposes that the role of JH has changed from an exclusively reproductive function in primitively eusocial species (those lacking morphologically distinct queen and worker castes), to an exclusively behavioral function in highly eusocial societies (those containing morphologically distinct castes). In contrast, the split-function hypothesis proposes that JH originally functioned in the regulation of both reproduction and behavior in ancestral solitary species. Then, when reproductive and brood-care tasks came to be divided between queens and workers, the effects of JH were divided as well, with JH involved in regulation of reproductive maturation of egg-laying queens, and behavioral maturation, manifested as age-correlated changes in worker tasks, of workers. We report experiments designed to test these hypotheses. After documenting age-correlated changes in worker behavior (age polyethism) in the neotropical primitively eusocial wasp Polistes canadensis, we demonstrate that experimental application of the JH analog methoprene accelerates the onset of guarding behavior, an age-correlated task, and increases the number of foraging females; and we demonstrate that JH titers correlate with both ovarian development of queens and task differentiation in workers, as predicted by the split-function hypothesis. These findings support a view of social insect evolution that sees the contrasting worker and queen phenotypes as derived via decoupling of reproductive and brood-care components of the ancestral solitary reproductive physiology.

Aging↗

Consistency between reproductive preferences and behavior: the Sri Lankan experience.

Data collected in the 1982 Sri Lanka Contraceptive Prevalence Survey and the 1985 Sri Lanka Contraceptive Survey, a follow-up study, were used to examine the reliability of respondents' preferences for additional children. At the aggregate level, consistency was remarkable: In 1982, 47 percent of women said they wanted more children and in 1985, 49 percent had more, for a slight excess of actual over wanted fertility. Even though inconsistencies existed, at the individual level preferences were moderately predictive of subsequent behavior. Unwanted fertility was related not only to the demographic characteristics of the women but also to disagreement with their husbands on desired fertility. More of those who believed that their husbands wanted additional children than those who believed otherwise reported births in the follow-up period. Nonusers of contraception were over three times more likely than contraceptors using modern methods to have had an unwanted birth.

Adult↗

Resveratrol: phytoestrogen effects on reproductive physiology and behavior in female rats.

Resveratrol is a phytoestrogen naturally found in grapes and is a major constituent of wine thought to exert both cardioprotective and chemopreventive activities. Recent studies show that this bioflavonoid binds to and activates gene transcription via the estrogen receptor (ER) subtypes ERalpha and ERbeta. Previous studies have focused primarily on the in vitro effects of resveratrol (RES) in estrogen-sensitive tissues or in carcinogenic cell lines, while frequently neglecting to document its potential effects in animal models with intact neuroendocrine systems. However, the present studies were designed to systematically characterize the in vivo effects of RES on reproductive physiology and behavior in adult female rats. In gonadally intact females, RES consumption reduced body weight, disrupted estrous cyclicity, and induced ovarian hypertrophy. However, in ovariectomized females RES (10-1000 microg) injections did not appear to mimic 17 beta-estradiol benzoate (EB)-induced behavioral responses and had no lasting effects on subsequent estrogen sensitivity or sociosexual behavior. The present studies support recent in vitro findings that RES differs from other phytoestrogens by acting as a possible mixed agonist/antagonist, depending on the availability of specific ER isoforms localized in the reproductive tract and brain of the female rat.

Animals↗

Male accessory gland secretions: modulators of female reproductive physiology and behavior.

Secretions of male accessory glands contain a variety of bioactive molecules. When transferred during mating, these molecules exert wide-ranging effects on female reproductive activity and they improve the male's chances of siring a significant proportion of the female's offspring. The accessory gland secretions may affect virtually all aspects of the female's reproductive activity. The secretions may render her unwilling or unable to remate for some time, facilitating sperm storage and ensuring that any eggs laid will be fertilized by that male's sperm. They may stimulate an increase in the number and rate of development of eggs and modulate ovulation and/or oviposition. Antimicrobial agents in the secretions ensure that the female reproductive tract is a hospitable environment during sperm transfer. In a few species the secretions include noxious chemicals. These are sequestered by developing eggs that are thereby protected from predators and pathogens when laid.

Animals↗

Behavioral facilitation of reproduction in sexual and unisexual whiptail lizards.

All-female, parthenogenetic species afford a unique test of hypotheses regarding the nature and evolution of sexuality. Mating behavior accomplishes the transfer of gametes and stimulates the coordination of reproductive activity of the male and female. Cnemidophorus uniparens, a parthenogenetic species, is believed to have resulted from the hybridization of two extant gonochoristic species, Cnemidophorus inornatus and Cnemidophorus gularis. C. uniparens regularly and reliably perform behaviors identical in form to those performed during mating by male C. inornatus. We have determined experimentally that individuals of the parthenogenetic species demonstrating male-like pseudosexual behavior also share a similarity in function with males of the sexually reproducing species. The number of female C. inornatus ovulating increases, and the latency to ovulation decreases, if a sexually active conspecific male is present. A similar facilitatory effect on ovarian recrudescence occurs in the all-female C. uniparens in the presence of a male-like individual. These results show that behavioral facilitation of ovarian recrudescence is important in sexual and unisexual species. This may represent a potent selection pressure favoring the maintenance of male-typical behaviors, thus accounting for the display of behavioral traits usually associated with males in unisexual species of hybrid origin.

Animals↗

Progestin concentrations are increased following paced mating in midbrain, hippocampus, diencephalon, and cortex of rats in behavioral estrus, but only in midbrain of diestrous rats.

BACKGROUND: The progesterone (P(4)) metabolite, 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP), acts in the midbrain ventral tegmental area (VTA) to modulate the intensity and duration of lordosis. 3alpha,5alpha-THP can also have anti-anxiety and anti-stress effects in part through actions in the hippocampus. Separate reports indicate that manipulating 3alpha,5alpha-THP levels in the VTA or hippocampus respectively can influence lordosis and affective behavior. 3alpha,5alpha-THP levels can also be altered by behavioral experiences, such as mating or swim stress. Whether endogenous levels of 3alpha,5alpha-THP modulate and/or are increased in response to affective and/or reproductively-relevant behaviors was investigated. METHODS: In Experiment 1, rats in behavioral estrus or diestrus were individually tested sequentially in the open field, elevated plus maze, partner preference, social interaction, and paced mating tasks and levels of 17beta-estradiol (E(2)), P(4), dihydroprogesterone (DHP), and 3alpha,5alpha-THP in serum, midbrain, hippocampus, diencephalon, and cortex were examined. In Experiments 2 and 3, rats in behavioral estrus or diestrus, were individually tested in the battery indicated above, with, or without, paced mating and tissues were collected immediately after testing for later assessment of endocrine measures. RESULTS: In Experiment 1, behavioral estrous, compared to diestrous, rats demonstrated more exploratory, anti-anxiety, social, and reproductive behaviors, and had higher levels of E(2) and progestins in serum, midbrain, hippocampus, diencephalon, and cortex. In Experiment 2, in midbrain and hippocampus, levels of 3alpha,5alpha-THP and its precursor DHP were increased among rats in behavioral estrus that were mated. In diencephalon, and cortex, DHP levels were increased by mating. In Experiment 3, in midbrain, levels of 3alpha,5alpha-THP and its precursor DHP were increased among diestrous rats that were tested in the behavioral battery with mating as compared to those tested in the behavioral battery without mating. CONCLUSIONS: Increased levels of 3alpha,5alpha-THP in behavioral estrus versus diestrous rats are associated with enhanced exploratory, anti-anxiety, social, and reproductive behaviors. Rats in behavioral estrus that are mated have further increases in 3alpha,5alpha-THP and/or DHP levels in midbrain, hippocampus, diencephalon, and cortex than do non-mated rats in behavioral estrus, whereas diestrous rats only show 3alpha,5alpha-THP increases in midbrain in response to behavioral testing that included mating.

Animals↗

Comparative effects of progesterone and alphaxalone on aggressive, reproductive and locomotor behaviors.

Progesterone can reduce aggressive behaviors in rodents under various experimental conditions, but it could be argued that this effect is due to the well known anesthetic/sedative properties of some steroids. We have tested this hypothesis by comparing the effects of progesterone and the anesthetic progestin, alphaxalone, on the aggressive, reproductive and locomotor behaviors of hamsters. Locomotion is used as a sensitive index of sedative/soporific effects. Progesterone reduced aggressive behavior without depressing the general locomotor activity of the animals, and it also facilitated feminine sexual behaviors in both sexes. Alphaxalone induced mild sedation in hamsters but this did not decrease their aggressive display. Alphaxalone did not facilitate feminine sexual behavior in either sex. We proposed that the inhibitory effect of progesterone on hamster aggressiveness is unlikely to follow from the hormone's sedative properties.

Aggression↗

Molecular phylogeny analysis of fiddler crabs: test of the hypothesis of increasing behavioral complexity in evolution.

The current phylogenetic hypothesis for the evolution and biogeography of fiddler crabs relies on the assumption that complex behavioral traits are assumed to also be evolutionary derived. Indo-west Pacific fiddler crabs have simpler reproductive social behavior and are more marine and were thought to be ancestral to the more behaviorally complex and more terrestrial American species. It was also hypothesized that the evolution of more complex social and reproductive behavior was associated with the colonization of the higher intertidal zones. Our phylogenetic analysis, based upon a set of independent molecular characters, however, demonstrates how widely entrenched ideas about evolution and biogeography led to a reasonable, but apparently incorrect, conclusion about the evolutionary trends within this pantropical group of crustaceans. Species bearing the set of "derived traits" are phylogenetically ancestral, suggesting an alternative evolutionary scenario: the evolution of reproductive behavioral complexity in fiddler crabs may have arisen multiple times during their evolution. The evolution of behavioral complexity may have arisen by coopting of a series of other adaptations for high intertidal living and antipredator escape. A calibration of rates of molecular evolution from populations on either side of the Isthmus of Panama suggest a sequence divergence rate for 16S rRNA of 0.9% per million years. The divergence between the ancestral clade and derived forms is estimated to be approximately 22 million years ago, whereas the divergence between the American and Indo-west Pacific is estimated to be approximately 17 million years ago.

Journal Article↗

Behavioral facilitation of reproduction in sexual and parthenogenetic Drosophila.

In a normal bisexual laboratory strain of Drosophila mercatorum, females housed with either fertile or sterile males lay more eggs than do females housed in pairs or as isolates. Females of a derived parthenogenetic strain have suffered genetic loss of this behavioral facilitation of egg production, a loss comparable to the loss of sexual receptivity. Despite these losses there has been a large increase in fecundity in the parthenogenetic strain. These findings are compared with those in a parthenogenetic lizard.

Animals↗

Neural pathways involved in the photoperiodic control of reproductive physiology and behavior in female hamsters (Mesocricetus auratus).

Female hamsters received horizontal knife cuts to investigate the role of hypothalamic connections in the photoperiodic control of female reproductive functions. Knife cuts placed ventral to or through the paraventricular nucleus (PVN), but dorsal to the suprachiasmatic nucleus (SCN), prevented photoperiod-induced acyclicity and uterine regression in animals maintained under a nonstimulatory photoperiod for 10 weeks. The animals were then ovariectomized and tested for lordosis behavior following subcutaneous injections of ovarian hormones to investigate the photoperiodic modulation of female sexual behavior. Animals exposed to a nonstimulatory photoperiod were less behaviorally sensitive to treatment with estradiol benzoate (EB) alone, but did not differ from animals maintained under a stimulatory photoperiod when EB was combined with progesterone. The effect of photoperiod and behavioral sensitivity to hormone replacement was independent of the surgical condition. The results are consistent with the hypothesis that dorsal projections from the SCN to the PVN mediate gonadal responses to short photoperiods. They also indicate that photoperiod-induced changes in behavioral sensitivity to gonadal steroids may be mediated by neural pathways distinct from those that mediate the gonadal changes.

Animals↗