Chronic aortic denervation decreases anxiety and impairs social memory in rats

Modulation of nociception and pain-evoked neurobehavioral responses by levetiracetam in a craniotomy pain model

Traditional and novel analgesic modalities have been extensively tested for post-craniotomy pain management, yet the role of newer antiepileptic drugs in this area remains obscure. This study investigates the impact of levetiracetam (LEV) on pain modulation and neurobehavioral performance in a craniotomy model. Fifty-six Wistar rats were randomly assigned into seven groups: no intervention (CTRL), administration of placebo or LEV with no further intervention (PBO and LEV, respectively), and sham-operation or craniotomy in placebo (PBO-SHAM and PBO-CR, respectively) or LEV-treated rats (LEV-SHAM and LEV-CR, respectively). Pain was assessed by the rat grimace scale before, and at 8 and 24 h after craniotomy, following intraperitoneal injections of LEV (100 mg/kg twice daily) or normal saline two consecutive days before and on the craniotomy day. Elevated plus-maze and olfactory social memory tests were performed at 24- and 48 h post-craniotomy, respectively. Upon testing conclusion blood samples were collected for cytokines estimation. Levetiracetam administration enhanced antinociception in sham and craniotomy groups. In the elevated plus-maze test, LEV-CR rats spent more time in investigating open arms and performed more open arm entries than PBO-SHAM and PBO-CR animals. The olfactory test revealed no between-groups difference in acquisition time during first contact with a juvenile rat, while LEV-CR rats spent less time to recognize the same juvenile rat compared to PBO-SHAM and PBO-CR groups. Furthermore, LEV-treatment attenuated cortisol, interleukin-6 and TNF-a release, in sham and craniotomy animals. In conclusion, preemptive use of LEV decreases nociception, improves pain-evoked behavior and attenuates stress response in rats subjected to craniotomy.

Effects of long-term infliximab and tocilizumab treatment on anxiety-like behavior and cognitive function in naive rats

BACKGROUND

Circulating cytokines have been proposed to be implicated in the development of mood disorders and cognitive impairment. This study aims to examine the effect of chronic treatment with infliximab, a tumor necrosis factor-alpha (TNF-alpha) inhibitor, and tocilizumab, an antibody against interleukin-6 (IL-6) receptor on anxiety-like behavior and cognitive function.

METHODS

Twenty-eight male, Wistar rats were randomly allocated into negative control, vehicle, infliximab and tocilizumab groups. After 8 weeks of intraperitoneal drug administration, rats performed the elevated-plus maze, the elevated-zero maze, the olfactory social memory and the passive avoidance tests. Brain sections at the level of the hippocampus, the amygdala and the prefrontal cortex were histologically examined. Finally, hippocampal and amygdaloid brain-derived neurotrophic factor (BDNF) expression was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR).

RESULTS

Infliximab group exhibited a significantly higher number of entries and time spent into the open arms of the mazes, showing a lower level of anxiety. In the olfactory social memory test, tocilizumab significantly increased the ratio of interaction. Both infliximab- and tocilizumab-treated animals had a significantly lower latency time in the passive avoidance test that suggests an improved memory. Histological examination revealed similar morphology and neuronal density between groups. BDNF expression levels were significantly increased in the groups receiving anti-cytokine treatment.

CONCLUSIONS

Our findings suggest that long-term peripheral TNF-alpha and IL-6 inhibition improves anxiety and cognitive function in rats and leads to an increased BDNF expression in the brain.

Infliximab and Tocilizumab Reduce Anxiety-Like Behaviour and Improve Cognitive Performance in a Juvenile Collagen-Induced Arthritis Rat Model

Anxiety disorders and cognitive decline are highly prevalent in rheumatic diseases, including Juvenile Idiopathic Arthritis (JIA). In this study, we investigated the effect of long-term treatment with infliximab and tocilizumab on anxiety-like behaviour and cognitive performance in a juvenile collagen-induced arthritis (CIA) rat model. Forty-nine rats with established moderate arthritis were randomly allocated into 7 equal groups: negative control, vehicle, methotrexate, infliximab, tocilizumab, methotrexate + infliximab and methotrexate + tocilizumab groups. Behavioural tests were performed to evaluate anxiety-like behaviour and cognitive function. Neuropathological changes were investigated by histological examination at the level of the hippocampus, the amygdala and the prefrontal cortex. Also, the expression of Brain-Derived Neurotrophic Factor (BDNF), a biomarker associated with neuronal survival and plasticity, was determined in the hippocampus and the amygdala by RT-qPCR. We found that both infliximab and tocilizumab reduced anxiety-like behaviour in the elevated-plus and elevated-zero maze tests. Tocilizumab, also, improved cognitive function in the olfactory social memory and passive avoidance tests. Anti-cytokine treatment reversed the histopathological changes in the brain induced by CIA. BDNF expression was higher in all treatment groups and especially those receiving monoclonal antibodies combined with methotrexate. Our data provide evidence that chronic infliximab and tocilizumab treatment reduces anxiety-like behaviour, improves cognitive function, reverses neuropathological changes and increases central BDNF expression in a juvenile arthritis rat model. These findings may be translated to humans to address behavioural comorbidities associated with JIA.

Furosemide modifies heart hypertrophy and glycosaminoglycan myocardium content in a rat model of neurogenic hypertension

Hypertension is a major risk factor for atherogenesis and heart hypertrophy, both of which are associated with specific morphological and functional changes of the myocardium. Glycosaminoglycans (GAGs) are complex molecules involved both in tissue morphology and function. In the present study, we investigated the effects of neurogenic hypertension and subsequent antihypertensive treatment with furosemide, on heart hypertrophy and the content of GAGs in the myocardium. Neurogenic hypertension was achieved in male Wistar rats by bilateral aortic denervation (bAD). At days 2, 7 and 15 after surgery, animals were sacrificed and the hearts were dissected away, weighted, and homogenized. Total GAGs were assessed by measuring the uronic acid content colorimetrically and individual GAGs were isolated and characterized by enzymatic treatment, with GAG-degrading enzymes, using electrophoresis on polyacrylamide gradient gels and cellulose acetate membranes. In bAD-animals blood pressure, blood pressure lability, heart rate and heart weight were significantly increased 15 days postoperatively. These effects were prevented by treatment with furosemide. Major GAGs identified in the heart were chondroitin sulphates, heparin (H), heparan sulphate (HS) and hyaluronic acid. The content of uronic and the relative content of H and HS in the heart in bAD animals significantly decreased from day 2 to day 15 postoperatively. Furosemide prevented the bAD induced decrease in GAG content. Considering that H and HS are potent inhibitors of cardiomyocyte hypertrophy, our results indicate that heart hypertrophy induced by neurogenic hypertension may be associated with decreases in the relative content of heparin and heparan sulphate in the heart.