Evaluation of light/dark cycle in anxiety- and depressive-like behaviors after regular treatment with methylphenidate hydrochloride in rats of different ages

Abstract

Avaliação do ciclo claro e escuro no comportamento relacionado à ansiedade e à depressão em ratos de diferentes idades após tratamento crônico com hidrocloridrato de metilfenidato AbstractObjective: Methylphenidate hydrochloride is the most widely used medication for treatment and management of attention-deficit hyperactivity disorder. However, the chronic effects of methylphenidate hydrochloride on anxiety-and depressive-like rat behaviors remain poorly investigated. In this context, the present study evaluated the effects of treatment with methylphenidate hydrochloride on anxietyand depressive-like behaviors using young and adult rats during the light and the dark cycle. Method: Male Wistar rats (25 or 60 days old) received a once-daily (in either the light or dark cycle) methylphenidate hydrochloride (2mg/kg) or saline intraperitoneal injection for 28 days. We performed elevated plus maze and forced swimming test two hours after the last injection. Results: The light/dark cycle was a significant factor in the anxiety-like behaviors; however, no significant interaction between all three factors (cycle, age and methylphenidate hydrochloride) was found. Nevertheless, we observed a nominally significant interaction between the light/ dark cycle and age in the forced swimming test. Conclusion: Our results have shown that age and the light/dark cycle are more significant modulators of anxiety-and depressive-like behaviors than methylphenidate hydrochloride treatment. Descriptors

Factors influencing behavior in the forced swim test

“…A significant role of circadian rhythm has been reported in regulation of FST behavior [180,181]. In the mouse FST, the immobility duration was shorter at noon (12:00 PM–2 PM) than at midnight (12:00 AM–2:00 AM); in this experiment mice were kept under a 14/10 light/dark cycle (lights on at 4:00 AM and off at 6:00 PM) [182].…”

Methylphenidate treatment causes oxidative stress and alters energetic metabolism in an animal model of attention-deficit hyperactivity disorder

“…or saline injections were given to adults rats starting on PD 60 once daily for 28 days (last injections on PD 88). Each group had six to eight animals (23)(24)(25).…”

Methylphenidate treatment affects mitogen-activated protein kinase activation in the striatum of young rats

“…In this study, only 1 mg/kg increased the phosphorylation of ERK1 and 2 mg/kg decreased the phosphorylation of JNK1/2. Previous findings showed that MPD doses of ,5 mg/kg administered intraperitoneally better reflect those used clinically in patients (16) and previous studies showed that a dose of 2 mg/kg is utilised in studies on animals to investigate alterations in the CNS (8)(9)(10)(11)(12).…”

“…Young rats ( n = 10) were administered MPD [1, 2, 5, or 10 mg/kg; Ritalin ® (Novartis; East Hanover, NJ, USA) – racemic dextroand levo-MPD mixture dissolved in saline solution] once a day or an intraperitoneal injection of saline for 28 days (chronic treatment) or for 1 day (acute treatment). The acute treatment was at PD25 and the chronic treatment between PD25 and PD53 (8–12). Two hours after the last administration of MPD or saline, the animals were killed and their striatum was dissected and rapidly solubilised with SDS-stopping solution (4% SDS, 2 mM EDTA, 8% β-mercaptoethanol, and 50 mM Tris, pH 6.8).…”

“…The acute treatment was at PD25 and the chronic treatment between PD25 and PD53 (8)(9)(10)(11)(12). Two hours after the last administration of MPD or saline, the animals were killed and their striatum was dissected and rapidly solubilised with SDS-stopping solution (4% SDS, 2 mM EDTA, 8% bmercaptoethanol, and 50 mM Tris, pH 6.8).…”