sfn2003

Janssen WG, Andrews G, Tomey MI, Baxter MG, Morrison JH (2003) Combined bilateral perforant path lesions with lesions of the cholinergic system: an ultrastructural immunogold analysis of nmdar1 representation within the dentate gyrus. Neuroscience 2003 Abstracts 676.26. Society for Neuroscience, New Orleans, LA.

Summary: Alzheimer’s disease is characterized by deterioration of cholinergic input to the hippocampus, as well as degeneration of input from the entorhinal cortex to the dentate gyrus(DG). Studies have demonstrated an upregulation of the NMDA receptor subunit, NR1, following unilateral ablatement of the perforant path(pp). We hypothesized that cholinergic innervation might be essential for DG plasticity following pp ablation. Our study was designed to investigate the synaptic distribution of NR1 following combined 192 IgG-Saporin lesions of the medial septum/vertical diagonal band(MS/VDB) and bilateral(bilat) pp knife cut ablation. Animals received bilat-pp lesions 2-3 weeks days post MS/VDB and were sacrificed 17 days following pp lesion. Four groups of rats were tested: 1)MS-VDB with sham bilat-pp; 2)sham MS-VDB with bilat-pp; 3)MS-VDB with bilat-pp; 4)sham MS-VDB with sham bilat-pp. Using postembedding immunogold electron microscopy and SynBin, a program designed for quantification and compartmentalization of immunogold particles at the synaptic level, we investigated these effects in the outer molecular layer of the DG in a pilot study with 2 animals/group. Initial results suggest that the synaptic pools of NR1 within post-synaptic compartments were not affected with single MS/VDB, but that a long term synaptic down regulation of NR1 follows bilat pp lesion that is not affected by the additional removal of cholinergic input. While these combined lesions do not alter the pattern of synaptic NR1 receptor distribution following pp lesions, these data has important implications for lesion-induced hippocampal plasticity as well as structural and functional recovery.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Sherren N, Pappas BA (2003) Dendritic dysgenesis in midline cortical regions following selective acetylcholine and dopamine lesions in neonatal rats. Neuroscience 2003 Abstracts 457.11. Society for Neuroscience, New Orleans, LA.

Summary: Both acetylcholine (ACh) and dopamine (DA) afferents reach their cortical targets during periods of synaptogenesis, and are perfectly positioned to influence the cytoarchitectural development of cortical neurons. Thus the behavioural outcomes of these lesions may be related to the development of appropriate dendritic morphology in neurons from cortical regions involved in cognition. Previous studies have either used non-specific lesion techniques or have not examined long-term effects. We lesioned rat pups at P7 with either 600 ng of the selective immunotoxin 192 IgG-saporin, or 150 ug of 6-hydroxydopamine preceded by desmethylimipramine, or both, and aged them to four months. One squad of rats was sacrificed for neurochemistry and another was prepared for morphological analysis using Golgi-Cox stain. The ACh lesion caused a 32% decrease in choline acetyltransferase activity in the frontal/cingulate cortex and a 72% reduction in retrosplenial cortex (RSC). This was associated with reductions in total dendritic length of the apical tree of layer V pyramidal cells in the medial prefrontal cortex (mPFC), the apical tree of layer III pyramidal cells in the anterior cingulate cortex (ACC), and the basal tree of layer III pyramidal cells in RSC. The DA lesion caused a 76% reduction in DA levels in frontal/cingulate cortex and no change in RSC levels. This was associated with reductions in total dendritic length of the basal and apical trees of layer V pyramidal cells in mPFC, and the basal tree of layer III pyramidal cells in ACC. No changes in layer III pyramidal cells were noted in RSC following the DA lesion. These data demonstrate that ascending ACh and DA afferents play a vital role in the cytoarchitectural development of the cortex. This is particularly important considering that hypofunction in these systems is a characteristic feature of neurodevelopmental disorders involving mental retardation, such as Rett and Down syndrome.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Neale JJ, Goodchild AK, Dampney RAL, Pilowsky PM (2003) Destruction of brainstem catecholamine neurons attenuates somatosympathetic reflex and responses to cholecystokinin. Neuroscience 2003 Abstracts 501.11. Society for Neuroscience, New Orleans, LA.

Summary: The integrity of the rostral ventrolateral medulla (RVLM) is essential for the expression of many sympathetic reflexes and the maintenance of vasomotor tone. The RVLM contains bulbospinal neurons, of which about half are catecholaminergic (C1). Destruction of bulbospinal C1 neurons leads to attenuation or abolition of the sympathetic baroreflex and chemoreflex, respectively. This study examines the effects of such destruction on blood pressure (BP), the somatosympathetic reflex and responses to intravenous (i.v) cholecystokinin (CCK) in urethane-anaesthetised, paralysed and ventilated Sprague-Dawley rats. Eighty percent of the spinally projecting C1 neurons in the RVLM were destroyed by bilateral microinjections of the immunotoxin, anti-DBH-saporin (12ng/100nl), into the intermediolateral cell column of the thoracic spinal cord (T1-2). Following treatment with the neurotoxin, systolic BP was measured for 3-5 weeks before testing the reflexes. No significant changes in systolic BP were observed. In the present study destruction of bulbospinal C1 neurons attenuated the baroreflex, replicating the findings of Schreihofer and Guyenet (2000, Am J Physiol 279:R729-R742). Activation of the somatosympathetic reflex by electrical stimulation of the tibial nerve normally elicits two peaks in averaged splanchnic sympathetic nerve activity. Following destruction of C1 neurons, the threshold voltage was reduced and the second peak was either markedly attenuated or abolished at two times threshold voltage. Intravenous injection of CCK (1, 10 and 100mg/kg) elicited depressor and sympathoinhibitory responses that were significantly reduced following destruction of bulbospinal C1 neurons. These results demonstrate a key role of bulbospinal C1 neurons in the somatosympathetic reflex and the sympathetic responses to i.v CCK but not in the tonic control of blood pressure.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Recabarren MP, Valdes JL, Seron-Ferre M, Torrealba F (2003) Tuberomammillary nucleus lesion decreases the anticipatory events induced by restricted feeding in rats. Neuroscience 2003 Abstracts 510.19. Society for Neuroscience, New Orleans, LA.

Summary: Our previous studies indicate that the histamine-containing neurons of the tuberomammillary nucleus (TMN) become active in anticipation to feeding time in rats under a restricted feeding schedule. To assess the role of the TMN in this anticipatory activity in rats, we lesioned the TMN bilaterally with stereotaxic injections of 50ng ORX-SAP (Advanced Targeting System, CA). We analyzed the locomotor activity, core temperature and the feeding frequency exhibited by these animals during a restricted feeding protocol, where food was available between 10:00 h and 12:00 h for at least 2 weeks. Rats were implanted in the abdominal cavity with telemetric sensors (Minimitter, OR) to measure locomotor activity and core temperature. During the whole experiment rats were maintained in individual cages and under controlled photoperiod of 12 hours light and 12 hours dark, light were on at 07:00 h. We analyzed the 3 hours preceding food arrival. We checked the extent of TMN destruction by immunostaining the brain sections with antibody against adenosine diaminase (ADA), which colocalize with histaminergic neurons in the TMN. Control rats were subjected to the same procedures except for the injection of the ORX-SAP toxin. Results: Lesion rats showed a significant decrease in the number of ADA-ir neurons in the TMN, as well as a decreased anticipatory activity under restricted feeding in comparison with control rats. Lesion rats although awake before food arrival, were less eager to feed compared to controls, as assessed by food bin approaches. Control rats were slightly more active than lesion rats during restriction. In conclusion, the functional integrity of the TMN is required for the full expression of the anticipatory events that are stimulated by a restricted feeding schedule.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Hunter CL, Quintero EM, Gilstrap L, Bhat NR, Granholm AE (2003) Neuroinflammatory response to mu p75-saporin immunotoxin-induced degeneration of basal forebrain cholinergic neurons. Neuroscience 2003 Abstracts 527.15. Society for Neuroscience, New Orleans, LA.

Summary: Basal forebrain cholinergic neurons, which provide the major cholinergic innervation to the cortical regions and play a key role in the processing of information involved in cognitive processes, degenerate during both normal aging and Alzheimer’s disease. Neuroinflammation, specifically the activation of microglia, is known to affect the progression of neuronal degeneration. Activated microglia produce inflammatory mediators that have neuropathic as well as neuroprotective actions, and it has been suggested that inflammatory mediators produced by activated microglia may play a role in the decline of specific neuronal sub-types in neurodegenerative diseases. The immunotoxin mu p75-SAP has been shown to selectively destroy cholinergic neurons in the basal forebrain of mice, resulting in reduced choline acetyl-transferase activity and cognitive impairments. To characterize the inflammatory response to mu p75-SAP lesions, 3 month-old mice received icv injections of mu p75-SAP (3.6 mg) followed by treatment with an anti-inflammatory agent, minocycline (45 mg/kg i.p.), or saline. Seven days after lesioning, immunohistochemistry was used to analyze markers for cholinergic and non-cholinergic neurons and inflammation. Cholinergic lesioning resulted in a dramatic increase in CD45, a microglial marker, but no change in GFAP, an astroglial marker, in the basal forebrain region. Lesioned animals had elevated levels of phosphorylated p38, a MAP kinase protein involved in inflammatory pathways. Minocycline treatment reduced this inflammatory response. Furthermore, preliminary results suggest that animals treated with minocycline after mu p75-SAP lesioning are partially protected from cholinergic degeneration.

Related Products: mu p75-SAP (Cat. #IT-16)

Richerson GB, Nattie EE, Deneris ES, Lauder JM (2003) Serotonergic neurons and development: implications for normal brain function and human disease. Neuroscience 2003 Abstracts 329. Society for Neuroscience, New Orleans, LA.

Summary: Symposium. Serotonergic neurons have widely divergent projections to virtually all of the CNS, and are involved in a variety of brain functions. This symposium will focus on how dysfunction of 5-HT neurons during development can influence brain function throughout life. G Richerson will discuss pH chemosensitivity of 5-HT neurons, how this changes during development, and the emerging hypothesis that these neurons induce arousal, a feeling of suffocation and hyperventilation in response to increased CO2. E Nattie has used focal manipulations of the raphe in vivo, including cell specific killing with an antibody to the serotonin transporter conjugated to the toxin saporin, to show that dysfunction of 5-HT neurons may lead to a defect in physiologic regulatory processes that are important during development. E Deneris will discuss mutant mice lacking the Pet-1 ETS gene, in which the majority of CNS 5-HT neurons are missing. 25-30% of Pet-1 nulls die during the first postnatal week, which may result from abnormal respiration. Surviving adults display anxiety-like and aggressive behavior. J Lauder will discuss 5-HT as a differentiation signal in prenatal brain development and as a morphogen in craniofacial development. Effects of prenatal exposure to serotonergic drugs or neurotoxins on postnatal outcome will be described. The speakers will introduce new hypotheses about how dysregulation of 5-HT neurons and 5-HT receptors during development may lead to a variety of brain disorders such as SIDS, migraine, autism, panic attacks and anxiety.

Related Products: Anti-SERT-SAP (Cat. #IT-23)

Cooper-Kuhn CM, Winkler J, Kuhn H (2003) Altered neurogenesis after cholinergic forebrain lesion in the adult rat. Neuroscience 2003 Abstracts 348.9. Society for Neuroscience, New Orleans, LA.

Summary: Adult hippocampal neurogenesis has been shown to be functionally connected to learning and memory and at the same time to be regulated by a multitude of extracellular cues, including hormones, growth factors, and neurotransmitters. The cholinergic forebrain system is one of the key transmitter systems for learning and memory. Within the hippocampus and olfactory bulb, two regions of adult neurogenesis, cholinergic innervation is quite extensive. This experiment aims at defining the role of cholinergic input during adult neurogenesis by using an immunotoxic lesion approach. The immunotoxin 192IgG-saporin was infused into the lateral ventricle of adult rats to selectively lesion the cholinergic neurons of the cholinergic basal forebrain (CBF), which project to the dentate gyrus and the olfactory bulb. Five weeks after lesion the rate of neurogenesis declined significantly in the dentate gyrus and olfactory bulb granule cell layers, whereas the generation of neurons in the periglomerular region of the olfactory bulb was unaffected. The number of apoptotic cells increased specifically in the progenitor region of the dentate gyrus as well as in the periglomerular layer of the olfactory bulb. Therefore, one of the possible mechanisms by which acetylcholine could promote neurogenesis is by increasing the survival of progenitor and immature neurons. Neurotransmitters can alter the microenvironment of neural progenitor cells, whether directly or indirectly, and these changes lead to significant alterations in neurogenesis. In principle, the data suggest that acetylcholine is stimulatory to adult hippocampal neurogenesis, since neurotoxin lesions specific to this neurotransmitter system lead to a reduced number of new neurons.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Co C, Yin X, Johnson WE, Martin TJ, Smith JE (2003) The effects of IgG-192-saporin lesions of limbic forebrain on rat cocaine self-administration. Neuroscience 2003 Abstracts 422.3. Society for Neuroscience, New Orleans, LA.

Summary: The involvement of cholinergic neurons in cocaine self-administration has been recently demonstrated. This study was undertaken to further assess the role of cholinergic innervations of/ or interneurons in limbic brain regions previously shown to receive enhanced dopamine input during cocaine self-administration. Rats were trained to self-administer cocaine on an FR2 schedule using a within session dose intake procedure (3½ hour session with 1 hour access each to 0.17, 0.33 and 0.67 mg/infusion). The doses were then decreased systematically to threshold levels where only the highest dose was self-administered during the session. The cholinergic neurotoxin IgG-192-saporin (0.25 µg in 1 µl) or vehicle was then bilaterally administered into the posterior nucleus accumbens (NAcc) – ventral pallidum (VP). The saporin lesion resulted in a shift to the left in the dose intake relationship for cocaine self-administration with all three doses maintaining responding. The sham-vehicle treated rats continued to only sample the higher dose. Real time RT-PCR was used to assess the magnitude and extent of the lesion. Gene expression for p75 (the target for 192 IgG) and choline acetyltransferase (ChAT) were assessed in the NAcc, VP, caudate nucleus (CP) and diagonal band (DB) of these rats. Significant reductions in p75 and ChAT gene expression were seen in the DB and VP while only small decreases were seen in the NAcc and CP of the saporin treated rats. These data suggest that the overall influence of cholinergic neurons in the DB and VP are inhibitory to the processes underlying cocaine self-administration.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Parikh T, Lee S, Walker BR (2003) Inhibition within the nucleus tractus solitarius (NTS) ameliorates social deficits due to specific acetylcholine (ACh) or Purkinje cell lesions. Neuroscience 2003 Abstracts 423.18. Society for Neuroscience, New Orleans, LA.

Summary: Previously, we demonstrated that enhancement of GABA transmission, or blockade of ionotropic glutamate within rat brainstem structures, which mediate limbic-motor seizure control, attenuated behavioral deficits, which were similar to those seen in human patients with autism, due to developmental cerebellum lesions. Evidence suggests that within autism spectrum disorders, there is a decrease in cholinergic neurons in the forebrain and/or a loss of purkinje cells in the cerebellum which might account for these behavioral deficits. Therefore, in the present study, we tested the hypothesis that specific lesions to the rat ACh system or reduction of purkinje cells in the rat cerebellum would lead to specific alterations of social behavior. Furthermore, alterations in GABA and glutamate transmission within the NTS would correct these social deficits. We examined the effect of ACh or purkinje cell lesions on social behavior in rats by recording social interactions before and after bilateral saporin injections (192-IgG or OX-7; 2 µg/side). As compared to preinjection behavior, saporin injections decreased social interaction of adult rats. Bilateral microinjections of the GABA agonist muscimol (256 pmol) into the mNTS at least 10 minutes prior to behavioral testing returned the amount of social investigation of the lesioned animals to pre-saporin levels. These findings suggest that specific neuronal populations are responsible for mediating social behavior in rats, and that there is a functional connection between those systems and the brainstem structures utilized for seizure control.

Related Products: 192-IgG-SAP (Cat. #IT-01), OX7-SAP (Cat. #IT-02)

Ukairo OT, Arshad S, Gibbs RB, Johnson DA (2003) Selective cholinergic lesion of the medial septum impairs retention but not acquisition of a passive avoidance memory task. Neuroscience 2003 Abstracts 425.16. Society for Neuroscience, New Orleans, LA.

Summary: Infusion of 192 IgG-saporin (SAP) into the medial septum (MS) selectively destroys cholinergic neurons projecting to the hippocampus. This study examined the effect of such lesions on acquisition and retention using a passive avoidance paradigm. Male Sprague-Dawley rats received either SAP (.22 μg in 1 μl) or vehicle directly into the MS. Passive avoidance training began two weeks later. Training consisted of placing an animal into the lighted chamber of the apparatus and then delivering footshock (.75 mA, 1 sec.) when the animal moved into the adjacent darkened chamber. Training was repeated until animals avoided the dark chamber for 2 consecutive trials of 5 min. duration. Retention (latency to enter the dark chamber) was tested 1 week later. Results showed no effect of SAP lesion on the number of trials necessary to acquire avoidance behavior. In contrast, SAP-lesioned animals showed a significant impairment in retention, as evidenced by a 72% decrease in crossover latency one week following training. These results suggest that selective destruction of cholinergic septo-hippocampal projections impairs retention, but not acquisition, of passive avoidance behavior to aversive stimuli.

Related Products: 192-IgG-SAP (Cat. #IT-01)