Behavioral Animal Models

In this paper, I explore the premises underlying the problem of the evaluation of animal models. I argue that the presence of similarities and differences between the model and the modelled, although historically and currently a dominant antinomy framing evaluation, is not a bottom-line consideration. What is critical is 1) whether we learn and 2) whether we improve treatment through the animal model research. Similarity between model and modelled and the closely related concept of validity are not coterminus with these critical evaluative measures. In fact, differences between the model and modelled also can provide impetus to new understanding and treatment innovations. The apples and oranges argument -that model and modelled are incommensurable -whether based on theoretical or empirical grounds, is not an adequate critique. Continuing argument that relies heavily on similarities versus differences is unconstructive, reducing to the proverbial half-empty/half-full bottle argument.

In this paper, I explore the premises underlying the problem of the evaluation of animal models. I argue that the presence of similarities and differences between the model and the modelled, although historically and currently a dominant antinomy framing evaluation, is not a bottom-line consideration. What is critical is 1) whether we learn and 2) whether we improve treatment through the animal model research. Similarity between model and modelled and the closely related concept of validity are not coterminus with these critical evaluative measures. In fact, differences between the model and modelled also can provide impetus to new understanding and treatment innovations. The apples and oranges argument — that model and modelled are incommensurable — whether based on theoretical or empirical grounds, is not an adequate critique. Continuing argument that relies heavily on similarities versus differences is unconstructive, reducing to the proverbial half-empty/half-full bottle argument.

It is still unclear how sensory systems efficiently encode signals with statistics as experienced by animals in the real world and what role adaptation plays during normal behavior. Therefore, we studied the performance of visual motion-sensitive neurons of blowflies, the horizontal system neurons, with optic flow that was reconstructed from the head trajectories of semi-free-flying flies. To test how motion adaptation is affected by optic flow dynamics, we manipulated the seminatural optic flow by targeted modifications of the flight trajectories and assessed to what extent neuronal responses to an object located close to the flight trajectory depend on adaptation dynamics. For all types of adapting optic flow object-induced response increments were stronger in the adapted compared with the nonadapted state. Adaptation with optic flow characterized by the typical alternation between translational and rotational segments produced this effect but also adaptation with optic flow that ...

Background. Clinically, an increasing number of older recipients are listed for transplantation. We examined recipient age-associated alterations of the immune response and their effects on graft function. Methods. Three-and 18-month-old Lewis (LEW) rats received kidneys from 3-and 18-month-old Fischer 344 (F344) rats (1.5 mg/kg/d cyclosporine A for 10 days; n‫/6؍‬group) and were observed for 180 days. In additional groups, double kidney transplantations were performed to determine the impact of nephron mass and recipient age on graft outcome. Results. All young recipients but only 66% of old recipients survived the observation period. Increasing recipient age resulted in a significant decrease in renal allograft function (P<0.001), more advanced morphologic evidence of chronic allograft damage (P<0.001), and greater cellular infiltration (P<0.05) and major histocompatibility complex expression (P<0.01) within grafts. Additional in vitro studies examined age-related changes in the cellular immune response by enzyme-linked immunosorbent assay, fluorescence-activated cell sorter analysis, and alloreactive enzyme-linked immunospot: splenocytes from old LEW rats produced significantly more interleukin (IL)-2 (P<0.0001), IL-4 (P<0.05), interferon (IFN)-␥ (P<0.0001), and tumor necrosis factor-␣ (P<0.05). IFN-␥-producing memory-type T cells were significantly elevated in older rats (P<0.0001). Moreover, they revealed significantly more alloreactive T cells directed against F344 (146؎64.2 and 512؎277/10 6 T cells; P<0.05). Double renal allografts from young donors into old recipients confirmed an independent effect of recipient age on the acceleration of chronic graft deterioration. Conclusions. The enhanced cellular immune respon-siveness in elderly recipients was associated with advanced chronic graft injury. Clinically, older recipients may need a modified immunosuppression.

The effects of lifelong, moderate excess release of glutamate (Glu) in the CNS have not been previously characterized. We created a transgenic (Tg) mouse model of lifelong excess synaptic Glu release in the CNS by introducing the gene for glutamate dehydrogenase 1 (Glud1) under the control of the neuron-specific enolase promoter. Glud1 is, potentially, an important enzyme in the pathway of Glu synthesis in nerve terminals. Increased levels of GLUD protein and activity in CNS neurons of hemizygous Tg mice were associated with increases in the in vivo release of Glu after neuronal depolarization in striatum and in the frequency and amplitude of miniature EPSCs in the CA1 region of the hippocampus. Despite overexpression of Glud1 in all neurons of the CNS, the Tg mice suffered neuronal losses in select brain regions (e.g., the CA1 but not the CA3 region). In vulnerable regions, Tg mice had decreases in MAP2A labeling of dendrites and in synaptophysin labeling of presynaptic terminals; the decreases in neuronal numbers and dendrite and presynaptic terminal labeling increased with advancing age. In addition, the Tg mice exhibited decreases in long-term potentiation of synaptic activity and in spine density in dendrites of CA1 neurons. Behaviorally, the Tg mice were significantly more resistant than wild-type mice to induction and duration of anesthesia produced by anesthetics that suppress Glu neurotransmission. The Glud1 mouse might be a useful model for the effects of lifelong excess synaptic Glu release on CNS neurons and for age-associated neurodegenerative processes.

The effects of lifelong, moderate excess release of glutamate (Glu) in the CNS have not been previously characterized. We created a transgenic (Tg) mouse model of lifelong excess synaptic Glu release in the CNS by introducing the gene for glutamate dehydrogenase 1 (Glud1) under the control of the neuron-specific enolase promoter. Glud1 is, potentially, an important enzyme in the pathway of Glu synthesis in nerve terminals. Increased levels of GLUD protein and activity in CNS neurons of hemizygous Tg mice were associated with increases in the in vivo release of Glu after neuronal depolarization in striatum and in the frequency and amplitude of miniature EPSCs in the CA1 region of the hippocampus. Despite overexpression of Glud1 in all neurons of the CNS, the Tg mice suffered neuronal losses in select brain regions (e.g., the CA1 but not the CA3 region). In vulnerable regions, Tg mice had decreases in MAP2A labeling of dendrites and in synaptophysin labeling of presynaptic terminals; ...

Humans with underlying cardiovascular disease are at greater risk than humans with normal hearts for developing torsade de pointes (TdP) following exposure to some drugs that prolong ventricular repolarization. This study was designed to test the hypothesis that rabbits with ischemic myocardial failure are at similarly increased risk of developing QTc prolongation and TdP following exposure to escalating doses of drugs, which is known to have a capacity to induce TdP in humans. Coronary artery ligation was performed in 28 rabbits, causing significant (p < 0.05) reduction in left ventricular shortening fraction and systolic myocardial dysfunction 4 weeks after ligation in all operated animals compared to 38 normal, nonoperated controls. All studies were performed on rabbits anesthetized with ketamine (35 mg/kg) and xylazine (5 mg/kg). Rabbits were exposed to escalating doses of amiodarone (3, 10, 30 mg/kg/10 min), cisapride (0.10, 0.25, 0.50 mg/kg/10 min), clofilium (0.1, 0.2, 0.4 mg/kg/10 min), dofetilide (0.005, 0.01, 0.02, 0.04 mg/kg/10 min), quinidine (3, 10, 30 mg/kg/ 10 min), and verapamil (0.25, 0.5, 1.0 mg/kg/10 min). A greater percentage of rabbits with failing hearts developed TdP following intravenous infusion of escalating doses of dofetilide (85%), clofilium (100%), or cisapride (50%) than did normal rabbits exposed to the same drug protocol (20, 33, and 0%, respectively). None of the rabbits in either group developed TdP when exposed to escalating doses of amiodarone, verapamil, or quinidine. Two out of four test articles lengthened QTc more in rabbits with myocardial failure than in normals, and TdP occurred in 13 out of 28 rabbits with myocardial failure as opposed to only four out of 38 rabbits with normal myocardial function.

Phosgene is a chemical widely used in the plastics industry and has been used in warfare. It produces a life-threatening pulmonary edema within hours of exposure, to which no specific antidote exists. This study aims to examine the pathophysiological changes seen with low tidal volume ventilation (protective ventilation (PV)) strategies compared to conventional ventilation (CV), in a model of phosgene-induced acute lung injury. Anesthetized pigs were instrumented and exposed to phosgene (concentration ϫ time (Ct), 2,350 mg ⅐ min ⅐ m Ϫ3 ) and then ventilated with intermittent positive pressure ventilation (tidal volume (TV) ϭ 10 ml ⅐ kg Ϫ1 ; positive end expiratory pressure, 3 cm H 2 O; frequency, 20 breaths ⅐ min Ϫ1 ; fractional concentration of inspired oxygen, 0.24), monitored for 6 hours after exposure, and then randomized into treatment groups: CV, PV (A) or (B) (TV, 8 or 6 ml ⅐ kg Ϫ1 ; positive end expiratory pressure, 8 cm H 2 O; frequency, 20 or 25 breaths ⅐ min Ϫ1 ; fractional concentration of inspired oxygen, 0.4). Pathophysiological parameters were measured for up to 24 hours. The results show that PV resulted in improved oxygenation, decreased shunt fraction, and mortality, with all animals surviving to 24 hours compared to only three of the CV animals. Microscopy confirmed reduced hemorrhage, neutrophilic infiltration, and intra-alveolar edema.

Phosgene is a chemical widely used in the plastics industry and has been used in warfare. It produces a life-threatening pulmonary edema within hours of exposure, to which no specific antidote exists. This study aims to examine the pathophysiological changes seen with low tidal volume ventilation (protective ventilation (PV)) strategies compared to conventional ventilation (CV), in a model of phosgene-induced acute lung injury. Anesthetized pigs were instrumented and exposed to phosgene (concentration ϫ time (Ct), 2,350 mg ⅐ min ⅐ m Ϫ3 ) and then ventilated with intermittent positive pressure ventilation (tidal volume (TV) ϭ 10 ml ⅐ kg Ϫ1 ; positive end expiratory pressure, 3 cm H 2 O; frequency, 20 breaths ⅐ min Ϫ1 ; fractional concentration of inspired oxygen, 0.24), monitored for 6 hours after exposure, and then randomized into treatment groups: CV, PV (A) or (B) (TV, 8 or 6 ml ⅐ kg Ϫ1 ; positive end expiratory pressure, 8 cm H 2 O; frequency, 20 or 25 breaths ⅐ min Ϫ1 ; fractional concentration of inspired oxygen, 0.4). Pathophysiological parameters were measured for up to 24 hours. The results show that PV resulted in improved oxygenation, decreased shunt fraction, and mortality, with all animals surviving to 24 hours compared to only three of the CV animals. Microscopy confirmed reduced hemorrhage, neutrophilic infiltration, and intra-alveolar edema.

SummaryDietary restriction (DR) is well known as a nongenetic intervention that robustly extends lifespan in a variety of species; however, its underlying mechanisms remain unclear. We have found in Caenorhabditis elegans that dietary deprivation (DD) during adulthood, defined as removal of their food source Escherichia coli after the completion of larval development, increased lifespan and enhanced thermotolerance and resistance to oxidative stress. DD‐induced longevity was independent of one C. elegans SIRTUIN, sir‐2.1, which is required for the effects of DR, and was independent of the daf‐2/insulin‐like signaling pathway that independently regulates longevity and larval diapause in C. elegans. DD did not significantly alter lifespan of fem‐1(hc17); eat‐2(ad465) worms, a genetic model of DR. These findings suggest that DD and DR share some downstream effectors. In addition, DD was detrimental for longevity when imposed on reproductively active young adults, suggesting that DD may...

Gonadotropin-inhibitory hormone (GnIH) is a hypothalamic neuropeptide that inhibits gonadotropin secretion and socio-sexual behaviours. Oestrogen (neuroestrogen) synthesized in the brain from androgen by aromatase regulates male socio-sexual behaviours. Here we show that GnIH directly activates aromatase and increases neuroestrogen synthesis in the preoptic area (POA) and inhibits socio-sexual behaviours of male quail. Aromatase activity and neuroestrogen concentration in the POA are low in the morning when the birds are active, but neuroestrogen synthesis gradually increases until the evening when the birds become inactive. Centrally administered GnIH in the morning increases neuroestrogen synthesis in the POA and decreases socio-sexual behaviours. Centrally administered 17β-oestradiol at higher doses also inhibits socio-sexual behaviours in the morning. These results suggest that GnIH inhibits male socio-sexual behaviours by increasing neuroestrogen synthesis beyond its optimum co...

Impaired materno-placental perfusion causes two important obstetric complications, fetal growth restriction and preeclampsia. This study investigated whether adenoviral vector-mediated overexpression of vascular endothelial growth factor (VEGF) in the uterine arteries (UtAs) increases uterine artery blood flow (UBF). First-generation adenovirus vectors (5 Â 10 11 particles) containing the VEGF gene (Ad.VEGF-A or -D) or the b-galactosidase reporter gene (Ad.lacZ) were injected into the UtAs of pregnant sheep (n ¼ 6) at 88-102 days of gestation (term ¼ 145 days). UBF was measured using Doppler sonography before, and 4-7 days after injection. Mean UBF increased significantly from 233 ± 156 (s.d.) ml min À1 to 753 ± 415 ml min À1 following Ad.VEGF-A injection (P ¼ 0.005, n ¼ 5); Ad.lacZ infection had no significant effect. Organ bath experiments on uterine arterial sections 4-7 days after injection showed that, compared with Ad.lacZ vessels, Ad.VEGF-A-transduced vessels had a reduced contractile response to phenylephrine (E max 148 ± 10.9 vs E max 228.2 ± 27.5, Po0.05) but increased relaxation with bradykinin (pD2 (Àlog EC 50 ) values 9.11 ± 0.01 vs 8.65 ± 0.11, Po0.05). Injection of Ad.VEGF-A into the UtAs increases UBF by enhancing vasodilatation. This may provide the basis for therapy in pregnancies complicated by uteroplacental insufficiency.

This study aimed to define the molecular mechanism during induction of spontaneous liver transplant tolerance using microarrays and to focus on molecular pathways associated with tolerance by meta-analysis with published studies. The differences in the early immune response between PVG to DA liver transplant recipients that are spontaneously tolerant (TOL) and PVG to Lewis liver transplants that reject (REJ) were examined. Spleens from TOL and REJ on days 1 and 3 were compared by 2 color microarray. Forty-six of 199 genes differentially expressed between TOL and REJ had an immunological function. More immune genes were increased in TOL vs. REJ on day 1, including STAT-1, IRF-1 and complement C3. Differential expression of selected genes was confirmed by quantitative RT-PCR. The results were compared to two published high-throughput studies of rat liver transplant tolerance and showed that C3 was increased in all three models, while STAT-1 and IRF-1 were increased in two models. The early increases in immune genes in TOL confirmed previous reports of an active early immune response in TOL. In conclusion, the increase in STAT-1, IRF-1 and complement component C3 in several models of liver transplant tolerance suggests that the STAT-1/IRF-1 apoptotic pathway and C3 may be involved in the tolerogenic mechanism.