ABSTRACT
BACKGROUND: Patients with chronic pain frequently suffer affective disorders, particularly anxiety and depression. Although clinical research on the relationship between pain and depressive symptoms has been done, it is not clear whether pain causes depression or depression exaggerates pain. To investigate the relation between pain and affect, we measured anxiety and depression-related behaviors in mice after spinal nerve ligation using classical behavioral tests. METHODS: After unilateral ligation of the left fifth lumbar nerve, we measured pain behaviors using von Frey and radiant heat tests. Activity level, anxiety-related behaviors, and depression-related behaviors were tested with open field, light-dark exploration, elevated plus-maze, and forced swim tests. RESULTS: Sensory hypersensitivity was observed within a few days after ligation. Anxiety and depression-related behaviors were not seen 2 and 7 days after ligation. However, 15 and 30 days after ligation we found clear evidence of anxiety and depression-related behaviors, without loss of mobility. CONCLUSIONS: Nerve injury can trigger affective disturbances in mice that appear much later than sensory hypersensitivity.
Subject(s)
Anxiety/psychology , Behavior, Animal , Depression/psychology , Peripheral Nervous System Diseases/psychology , Animals , Anxiety/etiology , Anxiety/physiopathology , Behavior, Animal/physiology , Depression/etiology , Depression/physiopathology , Male , Mice , Mice, Inbred C57BL , Peripheral Nervous System Diseases/complications , Peripheral Nervous System Diseases/physiopathologyABSTRACT
The aim of the study was to assess a new expiratory support (ES) system in resolving air trapping in the lungs during mechanical ventilation. The ES system consisted of a cylinder and two valves that were connected to the ventilatory circuit. The movements of them were synchronized with the ventilator. The cylinder aspirated gas during expiration. We compared the effects of the ES on air trapping between a narrower and an ordinary size endotracheal tube (ETT) (internal diameter (ID): 5 and 8 mm). In addition, we compared the effects of the ES on air trapping between normal and high airway resistance of the lungs (5 and 20 cm H(2)O/L/s). The ventilatory settings were as follows: volume controlled ventilation with constant inspiratory flow rate; tidal volume, 0.5 L; inspiratory time, 1.0 s; expiratory time, 1.0, 1.5, or 2.0 s; and PEEP, 0 cm H(2)O. The ES normalized the end-expiratory alveolar pressure of the 5 mm ID ETT at a level similar to that of the 8 mm ID ETT. The ES also resolved the air trapping induced by the high airway resistance of the lungs. In conclusion, the ES system resolved the air trapping associated with a narrow endotracheal tube and high airway resistance of the lungs.
