ABSTRACT
Activation of 5-hydroxytryptamine (5-HT) 5-HT1A, 5-HT2C, 5-HT3, and 5-HT7 receptors modulates the excitability of cardiac vagal motoneurones, but the precise role of 5-HT2A/2B receptors in these phenomena is unclear. We report here the effects of intracisternal (ic) administration of selective 5-HT2A/2B antagonists on the vagal bradycardia elicited by activation of the von Bezold-Jarisch reflex with phenylbiguanide. The experiments were performed on urethane-anesthetized male Wistar rats (250-270 g, N = 7-9 per group). The animals were placed in a stereotaxic frame and their atlanto-occipital membrane was exposed to allow ic injections. The rats received atenolol (1 mg/kg, iv) to block the sympathetic component of the reflex bradycardia; 20-min later, the cardiopulmonary reflex was induced with phenylbiguanide (15 µg/kg, iv) injected at 15-min intervals until 3 similar bradycardias were obtained. Ten minutes after the last pre-drug bradycardia, R-96544 (a 5-HT2A antagonist; 0.1 µmol/kg), SB-204741 (a 5-HT2B antagonist; 0.1 µmol/kg) or vehicle was injected ic. The subsequent iv injections of phenylbiguanide were administered 5, 20, 35, and 50 min after the ic injection. The selective 5-HT2A receptor antagonism attenuated the vagal bradycardia and hypotension, with maximal effect at 35 min after the antagonist (pre-drug = -200 ± 11 bpm and -42 ± 3 mmHg; at 35 min = -84 ± 10 bpm and -33 ± 2 mmHg; P < 0.05). Neither the 5-HT2B receptor antagonists nor the vehicle changed the reflex. These data suggest that central 5-HT2A receptors modulate the central pathways of the parasympathetic component of the von Bezold-Jarisch reflex.
Subject(s)
Animals , Male , Rats , Bradycardia/physiopathology , /physiology , Reflex/drug effects , Vagus Nerve/drug effects , Analgesics/pharmacology , Atenolol/pharmacology , Biguanides/pharmacology , Bradycardia/chemically induced , Rats, Wistar , Reflex/radiation effects , Serotonin Receptor Agonists/pharmacology , Vagus Nerve/physiopathologyABSTRACT
@#ObjectiveTo observe the survival and pathway of regenerative axons of spinal motoneurons following root injury of brachial plexus (BPI) and to investigate the correlation between the pathway of regenerative axons and the recovery of motor function. Methods48 adult male SD rats were randomly divided into four groups: crush group, cut group, avulsion group and the control group. 2 months later, the functional recovery was evaluated with Grooming test. Fluorogold labeled regenerative motoneurons retrogradely when injected into the motor or sensory branch of musculocutaneous nerve. 3 d later, the C5-8 spinal cord were harvested and the regenerative motoneurons were counted. The survival neurons were counted with neutral red staining. ResultsThe number of survival neurons in the cut group (1005±89) were more than that of the avulsion group （881±76）, but less than the crush group (1126±25). The control group was the most (1900±39）. The regenerative motoneurons reinnervated motor branch were much more than that of the sensory branch in all groups. For the Grooming test, the grade in the crush group (3.42) was much higher than that of the avulsion (1.75) and cut (1.75) group. ConclusionRegenerative axons of spinal motoneurons reinnervate the motor branch after BPI. The number of survival neurons is different after different injuries, which associated with the motor functional recovery.
ABSTRACT
Este estudio analizó el efecto de la infección aguda con Trypanosoma cruzi sobre la histología del sistema nervioso central de ratas durante la gestación. Las ratas Wistar fueron infectadas por inoculación intraperitoneal de 5x10(4) tripanosomas sanguícolas de la cepa M/HOM/Bra/53/Y. Para obtener la preñez durante el ascenso de la parasitemia, las ratas en estrus del ciclo menstrual fueron apareadas con los machos a los 12 días posinfección (pi). Ratas vírgenes/infectadas, vírgenes/sanas y sanas/preñadas fueron usadas como controles. Altos niveles de parasitemia patente (PP), de 36 ± 2,9 a 55 ± 3,0 tripanosomas/mm³ de sangre en las ratas con 16 y 22 días de infección y con 6 y 12 días de gestación respectivamente fueron observados. La comparación de la PP entre las ratas infectadas/preñadas y vírgenes/infectadas fue significativa al 1 por ciento. A los 30 días pi las ratas fueron sacrificadas y el cerebro (C) y las regiones cervical (RC), torácica (RT), lumbar (RL) y sacra (RS) de la ME fueron fijadas en formalina al 10 por ciento, deshidratadas e incluidas con Paraplast. Los cortes de 7 μm coloreados con hematoxilina y eosina mostraron reacción inflamatoria de células polimorfonucleares, mononucleares y plasmocitos en contacto con los cuerpos neuronales del C de las ratas infectadas/preñadas. La comparación entre el número de linfocitos en los hemisferios derecho (HD) e izquierdo (HI) de 65 ± 6,3 y 48 ± 4,5 linfocitos en las ratas infectadas/preñadas y de 20 ± 2,0 y 13 ± 1,1 linfocitos en las ratas sanas/preñadas fue significativa (P<0,05). La comparación del número de linfocitos en los HD y HI de las ratas vírgenes/sanas vírgenes/infectadas no reveló diferencias. La disminución de motoneuronas (MN) de 35 ± 3,4 a 16 ± 1,7 en la RC, de 33 ± 3,1 a 21 ± 3,0 en la RT y de 31± 3,8 a 10 ± 1,8 en la RL, de la ME de las ratas infectadas/preñadas fue significativa (P<0,05) en comparación con el número de MN en la ME de las ratas sanas/preñadas....
This study analyzed the effect of acute infection with Trypanosoma cruzi on the histology of Central Nervous System (CNS) of rats during pregnancy. Wistar rats were infected by intraperitonealy inoculation of 5x10(4) blood trypomastigotes of the M/HOM/Bra/53/Y strain. To obtain pregnancies during the ascending phase of parasitemia, rats in estrus of its menstrual cycle were matched with males at days 12 after infection (pi). Virgin/infected, virgin/healthy and healthy/pregnant rats were used as controls. High levels of patent parasitemia (PP) of 36 ± 2.9 to 55 ± 3.0 tripanosomas/mm³ blood, were observed in rats between 16 and 22 infection days and between 6 and 12 pregnancy days respectively. The comparison of the PP between infected/ pregnant rats and virgin/infected rats was significant at 1 percent. At the 30 days pi rats were sacrificed. Brain (B) and regions cervical (CR), thoracic (TR), lumbar (LR) and sacra (SR) of Spinal cord (SC) samples were obtained and fixed in formalin to 10 percent, dehydrated and embedded in Paraplast. The sections (7 μm) stained with Hematoxylin and Eosin showed inflammatory reaction of polymorphonuclear and mononuclear cells and plasmocytes in contact with neurons of B of the infected/pregnant rats. The comparison between lymphocytes number in the right (HR) (65 ± 6.3) and left (HL) (48 ± 4.5) cerebral hemispheres of infected/pregnant rats and of 20 ± 2.0 and 13 ± 1.1 lymphocytes in healthy/pregnant rats was significant (P<0.05). The comparison between lymphocyte number in the HR y HL of the virgin/healthy rats and virgin/infected rats not showed differences. Motoneurons (MN) reduction of 35 ± 3.4 to 16 ± 1.7 in CR, of 33 ± 3.1 to 21 ± 3.0 in TR and of 31± 3.8 to 10 ± 1.8 in LR of the SC of infected/pregnant rats was significant (P<0.05), when they were compared with MN number in SC of healthy/pregnant rats. Reduction of MN of 53 ± 4.9 to 35 ± 3.4 in the CR and of 37 ± 3.3 to 22 ± 1.9 in the SR...
Subject(s)
Animals , Rats , Animals, Laboratory , Chagas Disease , Laboratory Infection , Spinal Cord/anatomy & histology , Central Nervous System/anatomy & histology , Trypanosoma cruziABSTRACT
Calbindin D-28K (CALB) is one of the calcium-binding proteins which is assumed to be buffering, transport of Ca2+, and regulation of various enzyme systems. In the spinal cord, a subpopulation of calbindin-immunoreactive neurons located in the ventral portion of lamina VII, medial to the motoneuron column, has recently been proposed to be Renshaw cells (RCs), that mediate recurrent inhibition of spinal alpha-motoneurons, based on the anatomical location. In this study, we have performed to investigate the correlation between RCs containing high levels of CALB and motoneurons in the ventral horn of lumbar spinal cord of the ataxic pogo mice, that characterized by a failures of interlimb coordination, and prolonged excessive tone of hindlimb extensor muscles. We have shown that CALB immunoreactive RCs was significantly decreased in the ventral horn of lumbar spinal cord of the ataxic pogo mice (p.0.05), when compared with the control mice. Whereas, CALB immunoreactivity expression levels were no difference in the dorsal horn. Furthermore, CALB protein was significantly decreased in the lumbar spinal cord of the ataxic pogo mice (p.0.01). However, there were no difference in the cervical and thoracic spinal cord of the between control and pogo mice. These results suggest that motoneurons of ventral horn of the lumbar spinal cord might be more excited state, results in the decreased CALB immunoreactive RCs have not mediated a motoneuron excitability, in the atxic mice, pogo.
Subject(s)
Animals , Mice , S100 Calcium Binding Protein G , Calcium-Binding Proteins , Hindlimb , Horns , Muscles , Neurons , Spinal CordABSTRACT
Objective To measure Ihe effect on rats spinal neuron flow according nerve roots repair time.Methods We adopted the experimental rats on the root avulsion and extravertebral foramen nerve root divison of C_(5～7).We divided them into four groupsin each which there were 16 ratsaccording the type of nerves root injury and repair timeGroup AC:the avulsed roots were reimplanted into the spinal cord and the transeeted roots were sutured to the proximal stump immediately.Group B,Dthe avulsed roots and the transected roots were reimplanted into the spinal cord or were sutured to the proximal stump in delayed 3 weeks each with 16 rats.At the different time point(3 weeks3 months6 months)through pathological examina- tion and immunohistological lechniques and nerve tracing techniqueswe examined the spinal cord and distal nerve trunk in order to observe the pathologic changes and axonal regeneration.Results Group A、C were much better than group B、D in the numberthe conformation and the degree of abatement of spinal motoneu- rons and nissl body.It is the same on the number and the development level of regenerating nerve fiber. Conclusion It had the advantage of neuronal protection and nerve regeneration that reparing the injured nerve roots earlv after nerve roots injury.
ABSTRACT
Objective To study the neurotrophic activity of Schwann cells derived neurotrophic factor (SDNF) on developing motoneurons Methods The right facial nerve of 14 neonatal SD rats was transected neonatal SD rats was transected. The rats were randomly divided into two groups. SDNF (10?g/d) was applied for 7 days in experimental group and PBS(loul) was received in contral group. The mounts and morphology of motoneurons were studied. Results The number and morphometry of experimental group was better than that of controlled group significantly. Conclusion SDNF could save facial motoneurons fron axotomy induced cell death in neonatal rats.
ABSTRACT
Objective To compare the effect of natural antioxidants TA9001 and EGb761 on c-jun, NOS expression and survival of spinal motoneurons following brachial roots avulsion. Methods One hundred and eighty adult Sprague-Dawley female rats were randomly divided into TA9001, ECb761 and control groups. The right C 5～T 1 nerve roots were avulsed and then the introperitoneal injection of 1ml of 0.5% TA9001, 0.5% EGb761 or normal saline was given immediately and once daily to the rats, respectively. The rats were killed after survival for 4 h, 12 h 1 d,3 d,5 d,and 1 week, 2 weeks, 4 weeks and 6 weeks. The cryostat sections of C 7 segment were prepared and carried with c-jun immunocytochemistry, NADPH-d histochemistry and neutral red counter stain. Results The c-jun and nNOS gene expression was only appeared in injured motoneurons. c-jun was first appeared at 4 h, reached its maximum at 1 d, and grandually decreased till 2 weeks. NOS was first checked at 5 d, mostly at 2 weeks and decreased until 6 weeks. Avulsed motoneuron death started at 2 weeks, reached its peak at 4～6 weeks. Both TA9001 and EGb761 can cause c-jun up-regulation, nNOS down-regulation and more motoneuron survival as compared to control. Furthermore, EGb761 had more power to enhance c-jun expression than TA9901 at each time point. Conclusion It seems that nNOS is more important in motoneuron death mechanism than c-jun. Treatment of either TA9901 or EGb761 can protect the injured motoneurons following root avulsion.