Behavioral, structural and molecular changes following long-term hippocampal IL-1β overexpression in transgenic mice.

Chronic neuroinflammation is associated with many neurodegenerative and neurocognitive disorders, yet few animal models exist to study the behavioral effects of prolonged neuroinflammation. Therefore, we recently developed a transgenic mouse model harboring an interleukin-1β excisional activation transgene (IL-1β(XAT)). These mice display localized IL-1β overexpression and resultant neuroinflammation for up to 1 year following transgene induction.

Early life stress effects on adult stress-induced corticosterone secretion and anxiety-like behavior in the C57BL/6 mouse are not as robust as initially thought.

Understanding environmental effects on mouse brain development would allow us to take advantage of powerful genetic tools to determine the interaction between genetic and epigenetic factors governing brain development in C57BL/6 mice. Experiment 1 examined whether time of day for neonatal manipulations affects adult stress-induced hormone secretion. Three rearing groups were examined: early handled (EH; dam removed 10 min/day); maternal separated (MS; dam removed 180 min/day); and an animal facility raised (AFR) control.

Associations between behavior, hormones, and Fos responses to novelty differ in pre- and post-pubertal grass rats.

As animals progress from one developmental stage to the next, the nature of the challenges they face can change in systematic ways, as do the mechanisms that enable them to deal effectively with them. Here we examined the changes in the behavioral patterns and neuroendocrine mechanisms associated with exposure to a novel environment before and after the transition from a pre- to a post-pubertal stage of development in the unstriped Nile grass rat (Arvicanthis niloticus), a murid rodent that appears to live in family groups in the wild. We introduced juvenile (28 days old) and adult (60 days old) grass rats to a novel glass aquarium where they were kept for 1 h; controls were maintained in their home cages during this time.

Peripheral triiodothyronine (T(3)) levels during escapable and inescapable footshock.

Changes in peripheral thyroid hormone levels are associated with changes in human affective disorders, particularly depression. In the current study we used an animal stress paradigm, proposed to be an animal model of depression, to examine peripheral T(3) levels during and after escapable or inescapable stress in adult male rats. In this model, one animal can control the termination of foot-shock stress by performing a lever press, and therefore experiences escapable stress.

Female pheromones stimulate release of luteinizing hormone and testosterone without altering GnRH mRNA in adult male Syrian hamsters (Mesocricetus auratus).

In many species chemosensory stimuli function as important signals that influence reproductive status. Neurons synthesizing the peptide gonadotropin-releasing hormone (GnRH) are critical mediators of reproductive function via their regulation of the hypothalamic-pituitary-gonadal (HPG) axis, and they are thought to be responsive to chemosensory information. In the present study, we sought to elucidate the effects of female chemosensory stimuli on the HPG axis in sexually naive adult male Syrian hamsters.

Differential early rearing environments can accentuate or attenuate the responses to stress in male C57BL/6 mice.

This study investigated the effects of neonatal handling and maternal separation on the development of anxiety behavior and the hypothalamic-pituitary-adrenal axis of C57BL/6 mice. We hypothesized short periods of neonatal handling would diminish anxiety and secretion of corticosterone, while longer periods of maternal separation would elevate anxiety and plasma corticosterone compared to a nonhandled group. Mice were bred and reared as follows.

Differential effects of chronic escapable versus inescapable stress on male syrian hamster (Mesocricetus auratus) reproductive behavior.

Stress decreases sexual activity, but it is uncertain which aspects of stress are detrimental to reproduction. This study used an escapable/inescapable stress paradigm to attempt to dissociate physical from psychological components of stress, and assess each component's impact on reproductive behavior in the male Syrian hamster (Mesocricetus auratus). Two experiments were completed using this protocol where two animals receive the same physical stressor (an electric footshock) but differ in the psychological aspect of control.

Redefining gonadotropin-releasing hormone (GnRH) cell groups in the male Syrian hamster: testosterone regulates GnRH mRNA in the tenia tecta.

Gonadotropin-releasing hormone (GnRH) regulates the production of testosterone via the hypothalamic-pituitary-gonadal axis and testosterone, in turn, regulates the GnRH system via negative feedback. We compared testosterone regulation of GnRH mRNA expression in four anatomically defined GnRH cell groups in juvenile and adult male Syrian hamsters, including a rostral population of GnRH cells in the tenia tecta. In situ hybridization histochemistry (ISHH) was used to measure GnRH mRNA in brains from castrated juveniles and adults treated with 0 mg or 2.

Chronic oral administration of clomipramine decreases sexual behavior in the male Syrian hamster (Mesocricetus auratus).

Previous studies have demonstrated that clomipramine (CLI), a selective serotonin reuptake inhibitor, has negative side effects on sexual behavior when administered to adult rats and humans. In addition, neonatal rat pups given chronic doses of CLI display similar sexual deficits upon sexual maturity. This study used two experiments to test the hypothesis that 2 weeks of CLI would cause a decrease in sexual motivation and performance in the male Syrian hamster (Mesocricetus auratus).