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Perinatal 17α-ethinylestradiol exposure affects formalin-induced responses in middle-aged male (but not female) rats
No full text17α-Ethinylestradiol (EE), the main component of the contraceptive pill, is a synthetic estrogen found in rivers of the United States and Europe as an environmental contaminant. It is one of the most studied xenoestrogens due to its possible effect on the reproductive system. In the present study we evaluated the modulation of pain responses induced by formalin injection (licking, flexing, paw-jerk) in 8-month-old male and female offspring of female rats treated with two different doses of EE (4ng/kg/day or 400ng/kg/day) during pregnancy and lactation. Spontaneous behaviors and gonadal hormone levels were also determined. Both concentrations of EE induced an increase of pain behaviors in males only, i.e. higher flexing and licking of the formalin-injected paw than in OIL-exposed rats, during the second, inflammatory, phase of the formalin test. Grooming duration was increased by EE exposure in both males and females. Prenatal EE exposure (both concentrations) decreased estradiol plasma levels in the formalin-injected females but not in the males. These results underline the possibility that exposure to an environmental contaminant during the critical period of development can affect neural processes (such as those involved in pain modulation) during adulthood, indicating long-term changes in brain circuitry. However, such changes may be different in males and females
Analysis of different forms of aggression in male and female mice:Ethopharmacological studies
No full textBehavioral effects of testosterone in relation to social rank in the male rabbit
No full textThe role of gonadal androgens in favoring the adaptation to environmental pressure, including social organization, is well known. In the rabbit, testosterone administration increases marking behavior, and its level can be affected by agonistic interaction. In this experiment, we studied the effect of subcutaneous administration of testosterone propionate (TP) (3 mg/d for 6 days) in male rabbits belonging to the same social group (6 groups of 4 animals). In 2 additional groups (4 animals each), males were injected with almond oil. The animals were observed for 6 days in seminatural conditions, then treated with TP (or oil) and observed for another 6 days. The dominant/subordinate frequency ratio of behavioral patterns was used to rank the animals. The testosterone plasma concentration was correlated with agonistic behavior after the first period of social interaction. A significant increase of marking, digging, and defensive activity was observed after TP administration in all animals independent of rank, whereas this increase was not present in animals treated with oil. Agonistic and interactive behaviors increased significantly after TP treatment only in the first-ranking animals. This indicates the influence of social rank in the modification of behaviors involving interactions among subjects © Wiley-Liss, Inc
Perinatal exposure to xenoestrogens affects pain in adult female rats
No full textEstrogens have a variety of effects in addition to their action on reproductive structures, including permanent effects on the Central Nervous System (CNS). Therefore environmental chemicals with estrogenic activity (xenoestrogens) can potentially affect a number of CNS functions. In the present experiment, female rats receiving ethynylestradiol (EE) or methoxychlor (MXC) via the mothers during pregnancy (pre) or lactation (post) were tested in comparison with females born from mothers treated with OIL. The Object Recognition, Plantar and Formalin tests were carried out to evaluate the effects of these compounds on integrated functions such as memory and pain. Testosterone and estradiol plasma levels were determined by RIA. The results of the Object Recognition and Plantar tests did not differ among groups. However the groups differed in the Formalin test since flexing duration was higher in the EE- and MXC-pre groups than in the EE- and MXC-post and OIL groups. Estradiol plasma levels were higher in EE-pre than in the other groups. These results confirm the possibility that estrogen-like compounds (EE and MXC) can affect complex neural processes like pain when taken during critical stages of CNS developmen
Offline consolidation of spatial memory: Do the cerebellar output circuits play a role? A study utilizing a Morris water maze protocol in male Wistar rats
Full text linkTo address whether the cerebellum takes part to spatial memory consolidation related to navigation, male Wistar rats were trained daily (4 days), in a Morris water maze to found a submerged escape platform by use of distal cues (place training test). Retention of the allocentric map was evaluated in the probe test (without platform), before the place test. Bilateral shutdown of deep cerebellar nuclei was carried by infusion of the GABA-A agonist muscimol (0.25 μl at 1 μg/μl) immediately after each place test. Histology revealed a dorsal dentate nucleus (DDN) group, with muscimol diffusion confined to dentate nuclei, and a ventromedial/dentate nuclei (VMDN) group, with muscimol additionally involving fastigial, interpositus and vestibular nuclei. In the place test, Vehicle, DDN and VMDN groups reduced latency and distance to the platform over the 4 days and within the single day, indicative of efficient acquisition and working memory; navigational trajectories however differed in that, while Vehicle and DDN groups evolved to use direct paths, VMDN group indulged to navigate in proximity to the platform, suggesting an impairment in refining the spatial map. In the probe test VMDN, unlike Vehicle and DDN animals, failed to develop a preference for the quadrant where the platform was previously located, indicating a consolidation deficit. In conclusion, ventromedial cerebellar related structures may contribute to the process of consolidation of an allocentric spatial memory: their inactivation may have impaired the offline integration of idiothetic information with allothetic signals within the navigational network, leading to a coarse resolution map. © 2019 Elsevier B.V
Pubertal exposure to estrogenic chemicals affects behavior in juvenile and adult male rats
No full textIn this paper, we tested the hypothesis that exposure to estrogens of different source and estrogenic potency at early puberty could affect the development of socio-sexual behavior in the male rat. Puberty is regarded as a second stage of the ontogenetic period, in the sexual maturation of mammals, particularly sensitive to gonadal hormone milieu. We treated animals orally, from postnatal day 23 to 30, with an environmentally compatible dose of bisphenol A (BPA, 40 microg/kg/day) and with a dosage of ethinylestradiol (EE, 0.4 microg/kg/day) comparable to the human oral contraceptives. Exposure to EE altered the temporal pattern of male sexual activity, reducing performance, in the adult animals; slight modifications, in the same direction, were observed with BPA. Short-term behavioral effects were observed in the treated animals, both with BPA and EE: the exploratory drive, directed to a stimulus object and to the environment, as well as to conspecifics, was reduced in the juveniles. Modifications in the circulating T levels were observed after treatments: T was reduced in the juveniles, both with BPA and EE. The decrement persisted in the adult animals but reached significance only in the BPA group. On the whole, effects of pubertal exposure on behavior are more marked with EE than BPA. This can be due to the much higher estrogenic potency of EE; the direction of the behavioral effects of BPA, compared with EE, is however indicative of an estrogenic mechanism
Analysis of different forms of aggression in male and female mice : ethopharmacological studies
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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