Acetylcholinesterase-positive Neurons Research Articles

Postnatal development of nitrergic and cholinergic structures in rat spinal cord.

Nitric oxide (NO) is known to be a freely diffusible gaseous neurotransmitter that is not requiring synaptic connection to exert its effects. Nitric oxide synthase (NOS), the enzyme responsible for NO synthesis can be visualised by nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry. Other neurotransmitter is a classical neurotransmitter acetylcholine (ACh), regulated by enzyme acetylcholinesterase (AChE) that hydrolyses the acetylcholine after its releasing. This work is presenting results of histochemical study of the NADPH-d and AChE expression (nitrergic and cholinergic neurons) in the spinal cord (SC) during various periods in its development. Specimens from Wistar rat pups in the age ranging from 1st to 21st postnatal days (P1-P21) have been compared with those of adult rats (P90). Transverse sections of the SC were evaluated by light microscope. In adults, the NADPH-d positivity was detectable in the neurons of superficial and deep layers of the dorsal horn, pericentral area and in the area of preganglionic autonomic nuclei. AChE positive structures were seen in the same locations as previous ones with the exception of two locations: in superficial layers of the dorsal horn AChE staining was absent, while in the ventral horn the groups of AChE positive motoneurons were found. At the perinatal period both NADPH-d and AChE positive neurons were stained from slight to moderate intensity only. During later developmental periods the staining gradually increased and achieved adult level of intensity on the day P21. Our results confirmed the presence of nitrergic and cholinergic neurons in investigated areas of the SC and indicated their fully functioning of NADPH-d and AChE positive structures in SC from the third postnatal week.

Different Patterns of Vasoactive Intestinal Polypeptide (VIP)-Immunoreactive and Acetylcholinesterase (AChE)-Positive Innervation in the Internal Carotid Artery and Cerebral Arterial Tree of the Quail

The innervation pattern of vasoactive intestinal polypeptide-immunoreactive (VIP-IR) nerves in the quail internal carotid artery (ICA) and cerebral arterial tree was investigated and compared with that of acetylcholinesterase-positive (AChE-P) nerves. The supply of VIP-IR nerves to the two arterial systems was distinctly richer than that of AChE-P nerves. It was focused mainly on the walls from the distal ICA to the caudal half of the anterior ramus (AR) through the cerebral carotid artery (CCA). Indeed, double staining clearly showed that numerous VIP+/AChE-axons were distributed over these arterial regions where VIP+/AChE+ or AChE+/VIP- axons were sporadic or often lacking. The finding that nerve bundles accompanying the ICA within the carotid canal contained abundant VIP+/AChE- nerve cells suggests that cerebrovascular VIP-IR nerves in the quail have their major source at these neurons and enter the cranial cavity through the CCA. Another significant finding was that a small number of nerve cells, which were mostly stained for AChE alone and occasionally for VIP alone or both, occurred in the major arteries located more rostral than the middle AR. Thus, the quail cerebral arterial tree, at least the rostral segment of the anterior circulation, is multiply innervated by these three distinct categories of the extracranial and intracranial VIP-IR and AChE-P neurons.

Effects of amyloid-beta on cholinergic and acetylcholinesterase-positive cells in cultured basal forebrain neurons of embryonic rat brain

The neurotoxic effects of amyloid-β 1–42 and amyloid-β 25–35 (Aβ) on cholinergic and acetylcholinesterase-positive neurons were investigated in primary cultures derived from embryonic 18-day-old rat basal forebrain. After various time intervals, the cultures were treated with 1, 5, 10 or 20 μM Aβ for different time periods. The cholinergic neurons and their axon terminals were revealed by vesicular acetylcholine transporter immunohistochemistry and the cholinoceptive cells by acetylcholinesterase histochemical staining. To assess the toxic effects of these Aβ peptides on the cholinergic neurons, image analysis was applied for quantitative determination of the numbers of axon varicosities/terminals and cells. The results demonstrate that, following treatment with 1 or 5 μM Aβ for 5, 10, 30, 60 or 120 min, no changes in vesicular acetylcholine transporter immunohistochemical staining were observed. However, after treatment for 30 min with 10 or 20 μM Aβ, the number of stained axon varicosities was reduced, and treatment for 2 h they had disappeared. In contrast, vesicular acetylcholine transporter-positivity could be seen in some of the neuronal perikarya even after 3 days after treatment. The acetylcholinesterase staining was homogeneously distributed in the control neurons. After Aβ treatment, the histochemical reaction end-product was detected in some of the neuronal perikarya or in the dendritic processes near to the soma. It is concluded that the neurotoxic effects of Aβ appear more rapidly in the cholinergic axon terminals than in the cholinergic and acetylcholinesterase-positive neuronal perikarya.

Suppression of the basic transcription element-binding protein in brain neuronal cultures inhibits thyroid hormone-induced neurite branching.

The molecular mechanisms underlying the effect of thyroid hormone (T(3)) on neurite outgrowth are unknown. We recently identified the small GC-box binding protein BTEB (basic transcription element-binding protein) as a T(3)-regulated gene in the developing rat brain. BTEB mRNAs are rapidly (by 1 h) up-regulated by T(3) in primary rat embryonic neuronal cultures. Antisense oligodeoxynucleotides (ODNs), added to the cultures, reduced by 60% the level of BTEB mRNA. Addition of BTEB antisense ODNs to the cultures, before the onset of neurite polarity, had no effect on neurite elaboration but significantly decreased, in a dose-dependent manner, the effect of T(3) on neurite branching. We then examined the effects of antisense ODNs on a thyroid hormone target neuronal population, i.e. the acetylcholinesterase-positive neurons after the onset of neurite polarity. Exposure to BTEB antisense ODNs completely abolished the effects of T(3) on neurite branching and on the elaboration of neuritic filopodia-like structures in acetylcholinesterase cells. By contrast, antisense ODNs did not alter the effect of T(3) on neurite length. Our results show that titration of BTEB levels by T(3) regulates the degree of neurite branching and that the T(3)-induced neurite elongation and the T(3)-induced neurite branching are regulated by distinct mechanisms.

Selective vulnerability of spinal cord motor neurons to non-NMDA toxicity.

We previously reported that alpha-motor neurons in organotypic cultures of rat spinal cord (OTC-SC) are resistant to excitotoxicity induced through NMDA receptors. Here we describe the effects of non-NMDA glutamate receptor agonists kainic acid (KA) and quisqualic acid (QUIS) on motor neurons in OTC-SC. Large ventral horn acetylcholinesterase-positive neurons (VHANs), most of which are motor neurons, were quite sensitive to QUIS and KA toxicity and displayed losses of 95% and 94%, respectively. Small VHANs were reduced by 41% and 61% only. Identical results were obtained in cultures stained for non-phosphorylated neurofilaments. These observations demonstrate that alpha-motor neurons are considerably more sensitive to KA and QUIS than to NMDA toxicity. The proposed excitotoxic mechanism of ALS, therefore, is most likely mediated through non-NMDA glutamate receptors.

Acetylcholinesterase positive neurons in the developing rat lumbar spinal cord

Acetylcholinesterase positive neurons in the developing rat lumbar spinal cord

Cholinoceptive neurons without acetylcholinesterase activity and enzyme-positive neurons without cholinergic synaptic innervation are present in the main olfactory bulb of adult rat.

Light and electron microscopic histochemistry revealed acetylcholinesterase-positive and acetylcholinesterase-negative neurons in the main olfactory bulb of adult rat. Their distribution patterns on various neuron types have been analysed in detail. (1) No acetylcholinesterase staining could be demonstrated in the granule cells which receive a large number of the cholinergic synapses. (2) In contrast, enzyme activity was present in the soma and dendrites in most of the non-cholinergic and non-cholinoceptive relay cells (mitral cells and tufted cells) and in a subset of short-axon interneurons, where cholinergic synapses could not be detected. (3) Within the neuropil of glomeruli, two compartments were present, one of which was free of acetylcholinesterase-positive structures, while many enzyme-positive neuronal elements were seen in the other. (4) Characteristically, cholinergic and non-cholinergic neuronal structures showed triadic arrangements. (5) The axonal release of acetylcholinesterase from cholinergic axons is probable. It is suggested that, in the olfactory bulb, acetylcholinesterase is release by cholinergic afferent axons, and it is the cholinergic synapses that determine which postsynaptic neurons are cholinoceptive rather than the intraneuronal presence of acetylcholinesterase. In the main olfactory bulb, the acetylcholinesterase present in the relay cells therefore appears to have functions other than the hydrolysis of acetylcholine.

Initial increase and subsequent loss of vasoactive intestinal polypeptide immunoreactivity in acetylcholinesterase-positive neurons of mouse islets transplanted to the kidney.

Collagenase-isolated pancreatic islets from C57BL/6J mice were cultured overnight and transplanted under the kidney capsule of non-diabetic syngeneic hosts. Cryostat sections of grafts and fresh islets were stained for acetylcholinesterase (AChE) and vasoactive intestinal polypeptide-like immunoreactivity (VIP-LI). Immediately after isolation, as well as 2-5 days after transplantation, VIP-LI- and AChE-positive nerve cell bodies were clearly seen in the periphery of the islets. Grafts 3-5 days old exhibited a transient and marked increase in VIP-LI nerve cell bodies and fibres. Seven days after transplantation VIP-LI nerve structures began to decrease in number and after 26-52 weeks they were no longer detectable. In contrast, AChE-positive nerve cell bodies and fibers, which showed a relatively constant pattern of distribution, were observed throughout the entire observation period. Restaining experiments demonstrated the coexistence of VIP-LI and AChE activity in the neurons. It is concluded that the grafts were extensively equipped with an intrinsic VIP-ergic and AChE-positive innervation. The initial, transient enhancement of VIP-LI expression probably reflects an adaptation of the neuro-insular complex to the preganglionic denervation, or to the ectopic environment, or both.

Transforming growth factor α differentially affects GABAergic and cholinergic neurons in rat medial septal cell cultures

The effects of transforming growth factor α (TGFα) on low and high density cultures of fetal (embryonic day 17) rat medial septal cells were investigated and in some instances, compared to those of epidermal growth factor (EGF). In high density cultures, TGFα induces a significant increase in the number of astroglia and microglia. While the effects of TGFα on the astroglia are more pronounced when compared to EGF, those on the microglia are less notable. In addition, TGFα produces a time- and dose-dependent decrease in the activity of choline acetyltransferase (EC 2.3.1.6) and a proportional decrease in the number of acetylcholinesterase-positive neurons in these high density cultures. However, although both EGF and TGFα decreased choline acetyltransferase activity maximally at the same concentration (10 ng/ml), the latter was consistently more potent. TGFα does not affect cholinergic cell survival but the expression of their chemical phenotype and does so indirectly via the glial cells. On the other hand, TGFα directly induces a dose and time-dependent increase in glutamic acid decarboxylase activity in these high density cultures without affecting the number of glutamic acid decarboxylase immunoreactive neurons. In low density cultures, TGFα acts as a general neuronal survival factor, affecting both cholinergic and GABAergic neurons. Here TGFα's neurotrophic activity is more evident than its effects on their chemical phenotype. These results suggest that TGFα exerts distinct and differential effects on the biochemical expression of two neuronal populations in the developing medial septum maintained in high density culture. Finally, as TGFα acts as a general neuronal survival factor in low density cultures, cell to cell interactions appear to be important in the ultimate response of these cells to this growth factor.

An immunohistochemical study on the innervation of two peptidergic (NPY and VIP) nerves in the cerebral arterial tree and choroid plexus of the newt (Amphibia: Urodela).

The pattern of neuropeptide Y (NPY)- and vasoactive intestinal polypeptide (VIP)-immunoreactive (IR) innervation was investigated in the cerebral arterial tree and choroid plexus of the newt by the use of an indirect immunofluorescence technique combined with chemical sympathectomy (6-OHDA). The data presented here, in conjunction with histochemical data reported previously, showed the following characteristic features of cerebrovascular innervation in this urodelan species. (1) The cerebral arterial tree and choroid plexus had unbalanced NPY-IR and VIP-IR innervation, characterized by the absence or a markedly lesser density of VIP-IR nerves. (2) All or nearly all of the NPY-IR nerves were sympathetic in nature. (3) A few cerebral perivascular NPY-IR nerves in some individuals originated from the sympathetic NPY-IR nerve cells intrinsic to the major cerebral arteries of the anterior circulatory system. (4) Acetylcholinesterase-positive neurons lacking both NPY and VIP immunoreactivities are a major nerve type in cerebrovascular parasympathetic innervation. The preferential NPY-IR innervation of the plexus microvascular-epithelial regions must be considered in relation to its special functions, such as the regulation of microcirculation, and cerebrospinal fluid (CSF) production and transportation. CSF is vital for the movement of nutrients and metabolites in the newt brain.

Innervation Pattern of Noradrenergic and Acetylcholinesterase-Positive Nerves in the Extracranial Internal Carotid Artery and Cerebral Arterial Tree of the Japanese Quail.

The density and distribution of noradrenergic (NA) and acetylcholinesterase-positive (AChE) nerves in the extracranial part of the internal carotid artery (eICA) and cerebral arterial tree of the Japanese quail were investigated using specific histochemical techniques. The eICA and the major cerebral arteries in this bird were richly supplied with a large number of NA nerves, but had a very poor or no supply of ACNE nerves. The cerebral arteries located more caudally than the proximal part of the anterior ramus were generally devoid of ACNE nerves, while the internal ethmoidal artery (IEA) was usually equipped with fiber bundles positive for AChE. The above finding suggests that all or nearly all of cerebral perivascular AChE nerves path through the ethmoidal foramen, and project to the cerebral arterial system via the IEA. This differs from the cerebrovascular NA Innervation in that NA nerves enter the cranial cavity through the IEA, ICA and the vertebral artery, mainly via the ICA. A significant finding is that a few AChE nerve cells are present on the major cerebral arteries of the internal carotid system, mainly the IEA. Thus, the quail cerebral arterial system is dually innervated by the axons from extrinsic and intrinsic AChE neurons in some individuals. The unique NA and AChE innervation in the eICA and cerebral arteries of the quail must be considered in relation to the presence of NA and cholinergic vasomotor mechanisms responsible for the regulation characteristic of cerebral circulation in this bird.

(-)-Nicotine Protects against Systemic Kainic Acid-Induced Excitotoxic Effects

(-)-Nicotine was shown to produce in vivo protection against neurobehavioral effects caused by systemically administered kainic acid (KA), an excitotoxin that has been widely used to induce temporal lobe convulsions including "wet dog shakes" in experimental animals. Rats pretreated with (-)-nicotine (0.5 mg/kg sc) 15 min before receiving KA (12.0 mg/kg sc) exhibited a marked reduction ( P < 0.5) in the number of wet dog shakes when compared to saline-pretreated rats. Similarly, little visible brain damage was found in the (-)-nicotine-pretreated rats, but a widespread reduction in acetylcholinesterase-positive neurons was noted in the hippocampal areas of the saline-pretreated animals. While the mechanism of neuroprotection of (-)-nicotine is still not known, these findings suggest that (-)-nicotine may act as a therapeutic agent for putative excitotoxin-mediated disorders.

The effect of nitric oxide synthase inhibition on quinolinic acid toxicity in the rat striatum.

Neurons containing reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase and acetylcholinesterase in the striatum are spared in Huntington's disease. It has been claimed that these neurons are also spared after intrastriatal injection of the N-methyl-D-aspartate receptor agonist, quinolinic acid. In the present study the effects of intrastriatal injection of quinolinic acid (15, 30 and 60 nmol) on neurons containing NADPH diaphorase and acetylcholinesterase were examined in rats. Neurons identified histochemically were counted in whole striatal sections at the level of the injection site and at 400 microns intervals anterior and posterior to the injection site. There was a dose-related reduction in the total number of NADPH diaphorase-containing neurons counted in these levels, but only a mild loss of acetylcholinesterase-containing neurons. Acetylcholinesterase-positive neurons were observed near the injection site following administration of all doses. The effects of the nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (50 mg/kg, i.p. twice daily for seven days), on quinolinic acid (30 nmol. day 5)-induced toxicity were also investigated. Striatal sections were stained for NADPH diaphorase-, nitric oxide synthase- and acetylcholinesterase-containing neurons and cells were counted in whole striatal sections at the level of the injection site and at four levels posterior to the injection site. Nitric oxide synthase activity was measured in striatal homogenates. NG-Nitro-L-arginine methyl ester did not protect against or potentiate the loss of NADPH diaphorase-, nitric oxide synthase- or acetylcholinesterase-containing neurons or the loss in nitric oxide synthase activity. Acute intrastriatal injection of quinolinic acid may not be a suitable model for Huntington's disease and a role for nitric oxide in quinolinic acid-induced toxicity is not supported in this model.

Expression of cholinergic phenotype by embryonic ventral horn neurons transplanted into the spinal cord in the rat

Solid grafts of E12 embryonic spinal ventral horn were transplanted into motoneuron-depleted adult lumbar spinal cord in the rat. A muscle was implanted parallel to the vertebral column with its nerve inserted into the lumbar cord at the site of transplantation so as to provide a target for innervation by the grafted neurons. Previous retrograde labelling studies have shown that modest numbers of grafted motoneuron-like cells participate in the muscle's reinnervation and these are often found outside the graft within the host spinal cord. However, Nissl stained sections show that larger numbers of neurons survive within tissue recognisable as being of graft origin. In this study we have examined the expression of acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) by neurons within the graft. These enzymes are involved in cholinergic neurotransmission and are characteristic of motoneurons. Thirty-four to seventy days following transplantation the grafts contained numerous neurons with acetylcholinesterase (AChE) activity. Different patterns of AChE staining were observed which probably reflected the degree of differentiation and maturation within the graft. AChE positive neurons were found in isolation or in groups resembling developing motor pools. Most of the AChE-positive neurons appeared immature with scant cytoplasm. However, neurons could be found which appeared relatively mature with a regularly shaped nucleus, prominent nucleolus and Nissl bodies. The grafts contained few AChE-positive axons and no dense plexuses of varicose fibres around the neurons such as are found around motoneurons in the mature ventral horn. Comparisons between the size of AChE-positive neurons in the graft and the size of AChE-positive neurons in the developing ventral horn found that the size of grafted neurons to be intermediate between the sizes of spinal motoneurons at E19 and P0. Far fewer grafted neurons were found to be immunoreactive for choline acetyltransferase (ChAT) than histochemically reactive for AChE. This was consistent with our findings in the spinal cord during normal development where we found that fixation and staining procedures which labelled adult motoneurons failed to reliably demonstrate ChAT immunoreactivety in normal motoneurons prenatally, although AChE histochemical reactivity could be demonstrated as early as E16. We conclude that the grafts contain numbers of immature motoneurons which fail to proceed beyond a certain stage of development, perhaps because of a failure to form appropriate efferent and afferent connections.

Excitotoxic lesions of rat basal forebrain: Differential effects on choline acetyltransferase in the cortex and amygdala

Previous studies have shown that basal forebrain lesions using different excitotoxins produce similar decreases in cortical choline acetyltransferase, but differential effects on memory. However, basal forebrain cholinergic neurons send efferents to the amygdala and cortex. The present studies compared the effects of several excitotoxins on choline acetyltransferase levels in both of these structures. Lesions of the basal forebrain were made in rats by infusing different doses of either α-amine-3-hydroxy-5-methyl-4-isoxazole propionic acid, ibotenic acid, quisqualic acid, quinolinic acid or N- methyl- d-aspartic acid and measuring choline acetyltransferase seven days later. All of the excitotoxins exerted a differential response on cholinergic neurons of the basal forebrain projecting to the cortex or amygdala. Quinolinic acid was a more potent neurotoxin to cholinergic neurons innervating the amygdala than those projecting to the cortex. In contrast, quisqualic acid and α-amine-3-hydroxy-5-methyl-4-isoxazole were more potent neurotoxins to the cortical projection. α-Amine-3-hydroxy-5-methyl-4-isozazole propionic acid was the most potent excitotoxin for destroying cholinergic neurons innervating either the cortex or amygdala. A parallel neurotoxic response was obtained in the cortex and amygdala following infusion of ibotenic acid or N- methyl- d-aspartic acid with little selectivity for choline acetyltransferase depletion in the cortex or amygdala. Histological analysis of the injection site revealed that acetylcholinesterase-positive neurons were destroyed by the excitotoxins in a dose-dependent manner. Excitotoxins (ibotenic acid, quinolinic acid, N- methyl- d-aspartic acid) that produce the greatest impairments in memory were found to produce the greatest depletion of choline acetyltransferase in the amygdala. These results might suggest that cholinergic neurons projecting to the amygdala play an important role in memory.

Epidermal growth factor affects both glia and cholinergic neurons in septal cell cultures

The effects of epidermal growth factor on high density primary cultures of fetal (embryonic day 17) rat septal cells were examined. Under serum-free conditions, the continuous exposure of these cultures to epidermal growth factor for seven days significantly decreased choline acetyltransferase (EC 2.3.1.6) activity in a dose-dependent manner. Maximal decreases were observed from 1 to 10 ng/ml epidermal growth factor. This effect was completely abolished by the addition of anti-epidermal growth factor antibodies. The epidermal growth factor-mediated decrease in choline acetyltransferase activity was culture-time dependent, being first detectable after five days of factor application and may likely represent an inhibition of the spontaneous increase in enzyme activity that occurs with time in culture. Concomitant with changes in enzyme activity, epidermal growth factor produced a significant and proportional decrease in the number of acetylcholinesterase-positive neurons. This decrease in acetylcholinesterase-positive cells did not reflect a decrease in cholinergic cell survival as nerve growth factor could restore the number of acetylcholinesterase-positive neurons in epidermal growth factor-treated cultures to control levels. Furthermore, in these high-density cultures, epidermal growth factor did not affect general neuronal survival, while it did produce an increase in the number and intensity of glial fibrillary acidic protein-immunoreactive astroglia as well as in the number of macrophage-like cells. The proliferative response of these non-neuronal cells to epidermal growth factor, as assessed by [ 3H]thymidine incorporation, was evident after three days of epidermal growth factor application, persisted thereafter, and could be antagonized by the inclusion of the antimitotic 5-fluorodeoxyuridine. Furthermore, 5-fluorodeoxyuridine completely blocked the epidermal growth factor-mediated decrease in choline acetyltransferase activity. However, when epidermal growth factor was tested in pure glial cultures, it only directly induced proliferation of astrocytes. These results suggest that the proliferative response of either one or both of these glial cell types in the mixed cultures may be indirectly affecting cholinergic cell expression.

Interleukin-6 and leukemia inhibitory factor promote the survival of acetylcholinesterase-positive neurons in culture from embryonic rat spinal cord.

Interleukin-6 (IL-6) and leukemia inhibitory factor (LIF) promoted the survival of acetylcholinesterase (AChE)-positive neurons in culture from embryonic E15 rat spinal cord. Half of the AChE-positive neurons died during 3-7 days in culture in the absence of IL-6 and LIF. However, IL-6 at a concentration of 5 ng/ml completely prevented the death of AChE-positive neurons. LIF at a concentration of 5 U/ml also stimulated the survival of neurons, although to a lesser extent than IL-6. IL-6 and LIF also increased the numbers of process-bearing neuron-like cells in culture. The dose-dependencies of IL-6 and LIF with regard to the survival of total neuron-like cells were different from those for AChE-positive neurons.

Differential effects of insulin on choline acetyltransferase and glutamic acid decarboxylase activities in neuron-rich striatal cultures.

We studied the effects of insulin, nerve growth factor (NGF), and tetrodotoxin (TTX) on cellular metabolism and the activity of glutamic acid decarboxylase (GAD) and choline acetyltransferase (ChAT) in neuron-rich cultures prepared from embryonic day 15 rat striatum. Insulin (5 micrograms/ml) increased glucose utilization, protein synthesis, and GAD activity in cultures plated over a range of cell densities (2,800-8,400 cells/mm2). TTX reduced GAD activity; NGF had no effect on GAD activity. Insulin treatment reversibly reduced ChAT activity in cultures plated at densities of greater than 4,000 cells/mm2, and the extent of this reduction increased with increasing cell density. The number of acetylcholinesterase-positive neurons was not reduced by insulin, suggesting that insulin acts by down-regulating ChAT rather than by killing cholinergic neurons. Insulin-like growth factor-1 (IGF-1) reduced ChAT activity at concentrations 10-fold lower than insulin, suggesting that insulin's effect on ChAT may involve the IGF-1 receptor. NGF increased ChAT activity; TTX had no effect on ChAT activity. These results suggest that striatal cholinergic and GABAergic neurons are subject to differential trophic control.

Acetylcholinesterase-containing neurons, substance P and enkephalin fibers in the ventral horns of developing human embryos and fetuses

The presence of the acetylcholinesterase neurons and substance P-like and enkephalin-like fibers in the various nuclear columns of the ventral horns of the spinal cords was studied in the developing human by acetylcholinesterase histochemistry and substance P and enkephalin immunohistochemistry. Acetylcholinesterase-positive neurons initially appeared in the lateral neuronal columns and eventually were also observed in the medial columns as well as the median columns at various levels of the spinal cord by 10 weeks' gestation. Acetylcholinesterase-positive neurons in the lower sacral levels were not detected until 11–12 weeks' gestation. Diffused substance P- and enkephalin-like fibers were demonstrated as early as 10 weeks' gestation but did not align with any particular nuclear column until after 15 weeks' gestation. These fibers further increased in length and adopted reticular branching patterns and many of these tended to surround the cell bodies of the nuclear columns. Possible interaction of acetylcholinesterase neurons and substance P and enkephalin fibers would commence by 15 weeks' gestation.

Ganglioside AGF2 prevents the cognitive impairments and cholinergic cell loss following intraventricular colchicine

Ganglioside AGF2 prevented the cognitive and locomotor alterations induced by intraventricular colchicine. Adult male rats were initially trained to perform a standard radial arm maze (RAM) task. Following training, they were injected intraperitoneally with 10 mg/kg AGF2 ( COL AGF2 ), cerebrospinal fluid ( CSF) AGF2 ) or the saline vehicle ( COL SAL , CSF SAL ) for 3 days prior to and for 14 days following the bilateral injection of colchicine ( 7 μ g 0.5 μ l ) or artificial CSF into the lateral ventricles. Colchicine ( COL SAL ) impaired performance of the standard RAM task as well as a working memory version of the task in which various delays were imposed between the fourth and fifth arm choices. Colchicine also produced a transient hyperactivity which subsided within 10 weeks following surgery. In contrast, AGF2 ( COL AGF2 ) prevented the impairments in RAM performance and the alterations in locomotor behavior. Colchicine also produced significant decreases in hippocampal ChAT activity and high affinity choline uptake that were prevented by prior treatment with AGF2. Finally, colchicine produced a 35% decrease in the number of acetylcholinesterase-positive (cholinergic) neurons in the medial septum and vertical limb of the diagonal band ( MS VLDB ) which was also prevented by AGF2. Thus, the behavioral and neurochemical protection afforded by AGF2 was paralleled by a prevention of the loss of hippocampal cholinergic parameters and cholinergic neurons in the MS VLDB .