La estimulación vaginocervical artificial modifica la frecuencia de contracciones uterinas durante el ciclo estral de la rata hembra

Las contracciones uterinas (CU) pueden participar en importantes procesos reproductivos, como el transporte de espermatozoides y el parto. La evidencia indica que las CU pueden ser inducidas por hormonas y estimulación vaginocervical (EVC) a través de vías neuroendocrinas, incluida la actividad de las glándulas pituitaria y ovarios. Evaluamos la frecuencia de CU después de la EVC en diferentes fases del ciclo estral (CE) en ratas hembras adultas. Treinta y seis ratas hembras fueron anestesiadas, y sus cuernos uterinos fueron expuestos a través de una incisión abdominal. La EVC incluyó intromisiones vaginocervicales (IVC) y distensión vaginal mediante la inserción de un tapón de silicón para imitar los efectos del tapón posteyaculatorio. El número de CU se midió: 1) antes y después de las IVC, 2) durante la distensión vaginal por el tapón de silicón, y después de que se retiró. Comparamos el efecto de la EVC en la cantidad de CU durante las diferentes etapas de la CE de ratas. Los resultados indicaron que la frecuencia de la CU basal fue mayor durante el proestro tardío y menor durante el diestro. Además, las intromisiones dieron como resultado una mayor actividad uterina. La EVC aumentó el número de contracciones durante todas las fases de la CE, excepto durante el diestro. Discutimos el papel de las hormonas y la estimulación sexual en la CU, y su posible implicación en los procesos reproductivos de las hembra

Characterization of four types of tail abnormalities in rats treated prenatally with valproic acid

Valproic acid (VPA) is an anticonvulsant drug used mainly for the treatment of epilepsy, bipolar disorder and schizophrenia. The VPA has been shown to be a potent teratogen that causes birth defects and malformations. Likewise, there are reports that suggest a relationship between the use of VPA during pregnancy and an increased incidence of children with neurological disorders such as autism. In humans, prenatal exposure to VPA produces malformations including dimorphic facial features suggestive of a lesion in the neural tube, as in the case of spina bifida, heart disease, limb defects and craniofacial anomalies as well as genital abnormalities. Herein we describe four tail abnormalities found in rats treated prenatally with valproic acid, which has been used as an animal model for the study of autistic features. These malformations may be associated with neural damage, but further studies are needed in order to correlate each tail abnormality with the kind of neural alterationEl ácido valpróico (AVP) es un fármaco anticonvulsivo usado principalmente para el tratamiento de la epilepsia, trastorno bipolar y esquizofrenia. Se ha demostrado que el AVP es un teratógeno potente que causa defectos de nacimiento y malformaciones. Así mismo, hay informes que sugieren una relación entre el uso de AVP durante el embarazo y un aumento de la incidencia de niños con trastornos neurológicos tales como el espectro autista. En los seres humanos, la exposición prenatal a la AVP produce malformaciones que sugieren un defecto durante el cierre del tubo neural, como es el caso de la espina bífida, enfermedades del corazón, defectos de las extremidades, anomalías craneofaciales, así como anomalías genitales. En el presente trabajo se describen cuatro anormalidades de la cola en ratas tratadas prenatalmente con ácido valpróico. Este tratamiento se ha utilizado como modelo animal para el estudio de rasgos autistas. Estas malformaciones pudieran estar asociadas con algún daño en el sistema nervioso, sin embargo se requieren más estudios para correlacionar cada anormalidad de la cola con el tipo de alteración neura

Dimorfismo cerebral y preferencia sexual en una rata pseudohermafrodita

The brain is sexually dimorphic because males express bigger nuclei in certain regions as compared to females. Brain dimorphism occurs during the perinatal period, much later than the period when genitals and accesory organs are formed. In general, it is well accepted the idea that sexual preference correlates with brain dimorphism, and not with genital phenotype. Method: In the present study we describe a male pseudohermaphrodite rat, which looked like female. We assessed its sexual partner preference before males and females in two separate tests and then its brain dimorphism and histology of genitals and accesory organs were analyzed. Results: they indicated that its partner preference was bisexual and its brain was also organized bisexually. We discuss the role of hormones in the organization of the brain and also the role of some brain nuclei with regard to sexual partner preference. Conclusion: A pseudohermaphrodite brain may express an intermediate dimorphism and correlate with bisexual partner preferenceEl cerebro es sexualmente dimórfico pues los machos tienen algunos núcleos cerebrales de mayor tamaño que las hembras. Tal dimorfismo ocurre en el periodo perinatal, mucho después de que se han formado los genitales y órganos accesorios. En general, es aceptada la idea de que la preferencia sexual de un individuo correlaciona con el dimorfismo cerebral y no con el fenotipo genital. Método: En el presente trabajo describimos a una rata macho pseudohermafrodita, la cual fenotípicamente parecía hembra. Se evaluó su preferencia de pareja sexual frente a machos y hembras en dos pruebas diferentes, y posteriormente se analizó el dimorfismo de algunos núcleos cerebrales y se describió la histología de genitales y algunos órganos accesorios. Resultados: mostraron que la preferencia de pareja fue bisexual y su cerebro también tenía una organización bisexual. Se discute el papel organizacional de las hormonas en el dimorfismo cerebral y el papel de los núcleos cerebrales en relación a la preferencia de pareja. Conclusión: El cerebro de un pseudohermafrodita puede tener un dimorfismo intermedio y correlacionar con conducta bisexua

Refinement of intraperitoneal injection of sodium pentobarbital for euthanasia in laboratory rats (Rattus norvegicus)

BACKGROUND: The Canadian Council on Animal Care and American Veterinary Medical Association classify intraperitoneal (IP) pentobarbital as an acceptable euthanasia method in rats. However, national guidelines do not exist for a recommended dose or volume and IP euthanasia has been described as unreliable, with misinjections leading to variable success in ensuring a timely death. The aims of this study were to assess and improve efficacy and consistency of IP euthanasia. In a randomized, blinded study, 51 adult female Sprague-Dawley rats (170–495 g) received one of four treatments: low-dose low-volume (LL) IP pentobarbital (n = 13, 200 mg/kg pentobarbital), low-dose high-volume (LH) IP pentobarbital (n = 14, 200 mg/kg diluted 1:3 with phosphate buffered saline), high-dose high-volume (HH, n = 14, 800 mg/kg pentobarbital), or saline. Times to loss of righting reflex (LORR) and cessation of heartbeat (CHB) were recorded. To identify misinjections, necropsy examinations were performed on all rats. Video recordings of LL and HH groups were analyzed for pain-associated behaviors. Between-group comparisons were performed with 1-way ANOVA and Games-Howell post hoc tests. Variability in CHB was assessed by calculating the coefficient of variation (CV). RESULTS: The fastest euthanasia method (CHB) was HH (283.7 ± 38.0 s), compared with LL (485.8 ± 140.7 s, p = 0.002) and LH (347.7 ± 72.0 s, p = 0.039). Values for CV were: HH, 13.4%; LH, 20.7%; LL, 29.0%. LORR time was longest in LL (139.5 ± 29.6 s), compared with HH (111.6 ± 19.7 s, p = 0.046) and LH (104.2 ± 19.3 s, p = 0.01). Misinjections occurred in 17.0% (7/41) of euthanasia attempts. Pain-associated behavior incidence ranged from 36% (4/11, LL) to 46% (5/11, HH). CONCLUSIONS: These data illustrate refinement of the IP pentobarbital euthanasia technique. Both dose and volume contribute to speed of death, with a dose of 800 mg/kg (HH) being the most effective method. An increase in volume alone does not significantly reduce variability. The proportion of misinjections was similar to that of previous studies

Immunodesign of experimental sepsis by cecal ligation and puncture

Sepsis remains a prevalent clinical challenge and the underlying pathophysiology is still poorly understood. To investigate the complex molecular mechanisms of sepsis, various animal models have been developed, the most frequently used being the cecal ligation and puncture (CLP) model in rodents. In this model, sepsis originates from a polymicrobial infectious focus within the abdominal cavity, followed by bacterial translocation into the blood compartment, which then triggers a systemic inflammatory response. A requirement of this model is that it is performed with high consistency to obtain reproducible results. Evidence is now emerging that the accompanying inflammatory response varies with the severity grade of sepsis, which is highly dependent on the extent of cecal ligation. In this protocol, we define standardized procedures for inducing sepsis in mice and rats by applying defined severity grades of sepsis through modulation of the position of cecal ligation. The CLP procedure can be performed in as little as 10 min for each animal by an experienced user, with additional time required for subsequent postoperative care and data collection