Chronic unpredictable stress (CUS) was used to study the effects of a long-term treatment with either caffeine (8 mg/kg, orally) or desipramine (DMI) (10 mg/kg, intraperitoneally) in Wistar rats. The CUS procedure was applied for 6 weeks. Animals underwent a 2-week drug-free CUS procedure. Drugs were administered for 4 weeks alongside the stress and both drug and stress were continued throughout the behavioral testing period. CUS-exposed rats showed depressive-like behavior with reduced weight gain, reduced consumption of sucrose solution, increased immobility in the forced swimming test, and hypolocomotion in an open field. For the open field and elevated plus maze, calculation of an anxiety index confirmed that CUS increased anxiety, which was accompanied by an increase in the core temperature. DMI counteracted these physical and behavioral changes. Caffeine caused similar effects to DMI on weight gain, motor activity, anxiety level, and core temperature. In CUS-exposed rats, caffeine showed antidepressant and anxiolytic activity, accompanied by increased hippocampal dopamine and serotonin levels. However, no significant change in weight gain or core temperature was observed after caffeine treatment in CUS-exposed rats. These results suggest that, similar to the antidepressant DMI, long-term caffeine exposure exerts an antidepressant and anxiolytic effect in the CUS model. The involvement of the dopaminergic and serotonergic systems is discussed.
Over the last 10 years, accumulated experimental and clinical evidence has supported the idea that AT1 receptor subtype is involved in epilepsy. Recently, we have shown that the selective AT1 receptor antagonist losartan attenuates epileptogenesis and exerts neuroprotection in the CA1 area of the hippocampus in epileptic Wistar rats. This study aimed to verify the efficacy of long-term treatment with losartan (10 mg/kg) after kainate-induced status epilepticus (SE) on seizure activity, behavioral and biochemical changes, and neuronal damage in a model of co-morbid hypertension and epilepsy. Spontaneous seizures were video- and EEG-monitored in spontaneously hypertensive rats (SHRs) for a 16-week period after SE. The behavior was analyzed by open field, elevated plus maze, sugar preference test, and forced swim test. The levels of serotonin in the hippocampus and neuronal loss were estimated by HPLC and hematoxylin and eosin staining, respectively. The AT1 receptor antagonism delayed the onset of seizures and alleviated their frequency and duration during and after discontinuation of treatment. Losartan showed neuroprotection mostly in the CA3 area of the hippocampus and the septo-temporal hilus of the dentate gyrus in SHRs. However, the AT1 receptor antagonist did not exert a substantial influence on concomitant with epilepsy behavioral changes and decreased 5-HT levels in the hippocampus. Our results suggest that the antihypertensive therapy with an AT1 receptor blocker might be effective against seizure activity and neuronal damage in a co-morbid hypertension and epilepsy.
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