Experimental neurology
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Experimental neurology · Jun 2011
Postnatal challenge dose of methamphetamine amplifies anticonvulsant effects of prenatal methamphetamine exposure on epileptiform activity induced by electrical stimulation in adult male rats.
Administration of psychostimulants is often associated with increased seizure susceptibility. In our previous studies prenatal methamphetamine (MA) exposure increased seizure susceptibility of adult rats in models of primarily or secondarily generalized seizures induced by convulsant drugs. The effect of a single MA challenge dose in adulthood on chemically induced generalized seizures however, depends on the prenatal MA exposure history. ⋯ Our data demonstrate that daily injection of MA (5 mg/kg) within prenatal period decreased the occurrence of WDS and SADs, and shortened the duration of ADs and SADs suggesting anticonvulsant effects. Moreover, the challenge dose of MA (1 mg/kg) increased seizure threshold in all groups of rats, shortened duration of ADs in controls and prenatally saline-exposed animals, shortened duration of SADs in prenatally saline-exposed rats and totally eliminated WDS in all groups. Thus, the present study demonstrates that both chronic prenatal MA exposure and a single dose of MA in adulthood decrease focally induced epileptiform activity in adult male rats.
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Experimental neurology · May 2011
Comparative StudyOlfactory ensheathing cells enhance Schwann cell-mediated anatomical and functional repair after sciatic nerve injury in adult rats.
Sciatic nerve injury results in axon damage, muscle degeneration, and loss of function. We compared the potential of Schwann cell (SC), olfactory ensheathing cell (OEC), or mixed SC/OEC transplants for anatomical and functional restoration after adult rat sciatic nerve transection. The cells were seeded into a 20mm long macroporous poly(dl-lactide-co-glycolide) acid conduit and grafted between the sciatic nerve stumps. ⋯ Our results revealed that OEC synergistically improve SC mediated sciatic nerve repair. The data emphasized the promise of SC/OEC transplants as artificial nerves for peripheral nerve repair. This article is part of a Special Issue entitled: Understanding olfactory ensheathing glia and their prospect for nervous system repair.
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Experimental neurology · Apr 2011
Comparative StudySex-related differences in descending norepinephrine and serotonin controls of spinal withdrawal reflex during intramuscular saline induced muscle nociception in rats.
Sex-associated differences in the perception and modulation of pain have widely been reported in humans as well as animals. The aim of the present study performed in conscious rats of both sexes was to systematically investigate the role of sex in endogenous descending controls of nociceptive paw withdrawal reflex during experimental muscle pain elicited by intramuscular (i.m.) injection with different doses (0.1-0.4 ml of 0.9-5.8%) of saline. Ipsilateral i.m. injection of 0.2-0.4 ml, but not 0.1 ml, isotonic (0.9%, IT) saline elicited long lasting (about 7d), secondary and contralateral mechanical hyperalgesia in female rats, whereas male rats exhibited a bilateral, short-term (less than 1d) mechanical hyperalgesia only during the exposure to 0.4 ml IT saline injection (P < 0.05). ⋯ In conclusion, sex-related differences are important in descending modulations of pain and anesthesia. Less noxious stimuli could activate descending inhibition in males but not females, whereas less noxious afferents may elicit descending facilitation in female, but not male rats. Central noradrenergic and serotonergic pathways are differently involved in the action of descending modulations of nociception in rats of both sexes.
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Experimental neurology · Apr 2011
Lesion of cholinergic neurons in nucleus basalis enhances response to general anesthetics.
Acetylcholine in the brain has been associated with consciousness and general anesthesia effects. We tested the hypothesis that the integrity of the nucleus basalis magnocellularis (NBM) affects the response to general anesthetics. Cholinergic neurons in NBM were selectively lesioned by bilateral infusion of 192IgG-saporin in adult, male Long-Evans rats, and control rats were infused with saline. ⋯ However, the behavioral excitation, as indicated by horizontal movements, induced by halothane was reduced in lesioned as compared to control rats. Reversible inactivation of NBM with GABA(A) receptor agonist muscimol increased slow waves in the neocortex during awake immobility, and prolonged the duration of LORR and loss of tail-pinch response after propofol, pentobarbital and halothane. In summary, lesion of NBM cholinergic neurons or inactivation of the NBM prolonged the LORR response to general anesthetic drugs.
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Experimental neurology · Mar 2011
Comparative StudyChronic dizocilpine or apomorphine and development of neuropathy in two rat models I: behavioral effects and role of nucleus accumbens.
Dopaminergic and glutamatergic inputs converge on nucleus accumbens (NAC) and affect the neuropathic pain. We tested the effects of daily systemic administration of dizocilpine (MK-801), a N-methyl-d-Aspartate (NMDA) noncompetitive receptor antagonist, or apomorphine (APO), a dopamine (DA) D1 and D2 receptor agonist, on neuropathic manifestations in the chronic constriction injury (CCI) and the spared nerve injury (SNI) models of mononeuropathy in rats. Six groups of rats were subjected to CCI or SNI neuropathy and 5-7 days later received daily intraperitoneal (ip) injections of saline, MK-801, or APO for two weeks. ⋯ Systemic daily injections of MK-801 and APO markedly attenuated the neuropathic manifestations in the CCI and SNI models with a minimal effect on cold allodynia. The same results were seen in the SNI model with chronic perfusion of NAC. Our results suggest that daily systemic administration of DA agonists and NMDA antagonists can attenuate neuropathic pain manifestations and that the NAC is involved in the modulation of neuropathic-like behaviors.