Behavioural pharmacology
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Ranolazine modulates the cardiac voltage-gated sodium channel (NaV 1.5) and is approved by the FDA in the treatment of ischemic heart disease. Ranolazine also targets neuronal (NaV 1.7, 1.8) isoforms that are implicated in neuropathic pain. ⋯ Both intraperitoneal and oral administration of ranolazine dose-dependently inhibited the mechanical and cold allodynia associated with spared nerve injury, without producing ataxia or other behavioral side effects. These data warrant clinical investigation of the potential use of ranolazine in the treatment of neuropathic pain.
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Behavioural pharmacology · Dec 2009
Intradorsal hippocampal microinjection of lithium reverses morphine-induced impairment of memory in mice: interactions with dopamine receptor mechanism(s).
In this study, the influence of lithium administration on morphine-induced memory impairment and possible interactions with dopamine receptor mechanism have been investigated. Considering that the dorsal hippocampus is involved in memory, lithium and dopamine agents were injected into the CA1 regions of this site (intra-CA1). For memory assessment, a one-trial step-down inhibitory avoidance task was used in adult male mice. ⋯ In contrast, pretest intra-CA1 administration of either D1 receptor antagonist SCH23390 (0.01-1 microg/mouse) or D2 receptor antagonist sulpiride (5-10 microg/mouse) inhibited the improvement of memory retrieval by lithium (4 microg/mouse, intra-CA1). Single pretest administration of SCH23390 or sulpiride neither elicited any response, nor reversed morphine-induced amnesia. In conclusion, it can be suggested that the dorsal hippocampal dopaminergic system is involved in the improving response of lithium on morphine-induced amnesia.
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Behavioural pharmacology · Oct 2009
The selective metabotropic glutamate receptor 7 allosteric agonist AMN082 inhibits inflammatory pain-induced and incision-induced hypersensitivity in rat.
This study characterized the contribution of metabotropic glutamate receptor 7 (mGlu7 receptor) activation to the development of inflammatory hyperalgesia and allodynia, using a novel, systemically active mGlu7 receptor allosteric agonist, N, N'-dibenzhydrylethane-1,2-diamine dihydrochloride (AMN082). The effects of AMN082 (0.1, 1 or 5 mg/kg, intraperitoneally; 5 or 50 nmol, intrathecally) or diclofenac (5 mg/kg, intraperitoneally) administered 30 min preprocedure or 3 h postprocedure on hindpaw withdrawal latency (in seconds) to thermal stimulation, and response threshold (in grams) to mechanical stimulation, were measured in adult rats (n = 6-8 per group) before and up to 24 h after intradermal injection of carrageenan into the hindpaw or hindpaw incision. ⋯ Intrathecal injection of AMN082 postcarrageenan and postsurgery also significantly attenuated thermal hyperalgesia. Enhancing endogenous mGlu7 receptor activity inhibits postinjury stimulus-evoked hypersensitivity and may be of therapeutic benefit for the treatment of inflammatory and incision-induced pain.
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Behavioural pharmacology · Mar 2009
Comparative StudyAdenosine receptor antagonists improve short-term object-recognition ability of spontaneously hypertensive rats: a rodent model of attention-deficit hyperactivity disorder.
The strain of spontaneously hypertensive rats (SHR) is considered a genetic model for the study of attention-deficit hyperactivity disorder (ADHD), as it displays hyperactivity, impulsivity and poorly sustained attention. Recently, we have shown the involvement of adenosinergic neuromodulation in the SHR's short-term and long-term memory impairments. In this study, we investigated the performance of male and female SHR in a modified version of the object-recognition task (using objects with different structural complexity) and compared them with Wistar rats, a widely used outbred rat strain for the investigation of learning processes. ⋯ T-shaped object), whereas SHR only discriminated the most structurally distinct pairs of objects (cube vs. pyramid). Pretraining administration of methylphenidate [2 mg/kg, intraperitoneal (i.p.)], caffeine (1-10 mg/kg, i.p.), the selective adenosine receptor antagonists DPCPX (8-cyclopenthyl-1,3-dipropylxanthine; A1 antagonist, 5 mg/kg, i.p.) and ZM241385 (A2A antagonist, 1.0 mg/kg, i.p.), or the association of ineffective doses of DPCPX (3 mg/kg) and ZM241385 (0.5 mg/kg), improved the performance of SHR in the object-recognition task. These findings show that the discriminative learning impairments of SHR can be attenuated by the blockade of either A1 or A2A adenosine receptors, suggesting that adenosinergic antagonists might represent potentially interesting drugs for the treatment of ADHD.
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Behavioural pharmacology · Feb 2008
Chronic stress in adulthood followed by intermittent stress impairs spatial memory and the survival of newborn hippocampal cells in aging animals: prevention by FGL, a peptide mimetic of neural cell adhesion molecule.
In this study, we examined whether chronic stress in adulthood can exert long-term effects on spatial-cognitive abilities and on the survival of newborn hippocampal cells in aging animals. Male Wistar rats were subjected to chronic unpredictable stress at midlife (12 months old) and then reexposed each week to a stress stimulus. When evaluated in the water maze at the early stages of aging (18 months old), chronic unpredictable stress accelerated spatial-cognitive decline, an effect that was accompanied by a reduction in the survival of newborn cells and in the number of adult granular cells in the hippocampus. ⋯ Administration of FGL, a peptide mimetic of neural cell adhesion molecule, during the 4 weeks of continuous stress not only prevented the deleterious effects of chronic stress on spatial memory, but also reduced the survival of the newly generated hippocampal cells in aging animals. FGL treatment did not, however, prevent the decrease in the total number of granular neurons that resulted from prolonged exposure to stress. These findings suggest that the development of new drugs that mimic neural cell adhesion molecule activity might be of therapeutic relevance to treat stress-induced cognitive impairment.