Choline acetyltransferase and acetylcholinesterase in fascia dentata following lesion of the entorhinal afferents

The perforant path (entorhino-dentate fibers) which terminates in the outer parts of the molecular layer of fascia dentata, was transected in adult rats. After 2–93 days survival, serial cryostat sections were prepared and either stained for acetylcholinesterase (AChE), cell bodies (thionin) and degenerating nerve terminals (Fink-Heimer), or freeze-dried for biochemical assay of choline acetyltransferase (ChAc), AChE and glutamate decar?ylase (GAD).There was a 50–60% increase in the activities of ChAc and AChE per weight or volume of tissue in the molecular layer of fascia dentata, being specifically localized to the zones where the degenerating nerve terminals are found. The increase was already fully developed at 8 days survival. Simultaneously, there was a moderate increase in GAD per amount of tissue, significantly smaller than that of ChAc and AChE. The latter effect was probably caused by the shrinkage of tissue due to loss of perforant path elements. Concomitantly with these changes there was an increase in width of the AChE-poor zone in the inner part of the molecular layer, which normally contains the terminals of the commissural and ipsilateral afferents from hippocampus (CA3).Transection of the septal afferents showed that the nerve elements responsible for the increased ChAc and AChE activities were of the same origin as the cholinergic elements normally present. Transection of another important afferent route to the fascia dentata, the commissural fibers, led to no changes in AChE staining.The results indicate that in response to degeneration of the afferents from the entorhinal area there occurs a reorganization of the nerve elements in the molecular layer of fascia dentata, including a relative increase of the cholinergic nerve terminals and axons.     

Choline acetyltransferase and acetylcholinesterase in the developing rat spinal cord

Microchemical procedures were employed for the quantitative assay of choline acetyltransferase (ChAc; EC 2.3.1.6) and acetylcholinesterase (AChE; EC 3.1.1.7) activity in the lumbar spinal cord of the rat during late fetal and early postnatal development. ChAc activity remained low from the 13th to the 17th day of gestation, increased five-fold from the 17th day of gestation through the end of the second postnatal week, and changed little thereafter. AChE activity increased 19-fold from the 13th day of gestation through the end of the second postanatal week. The ontogenetic patterns for the two enzymes were identical after the 16th day of gestation. When these changes in enzyme activity were correlated with morphological and functional differentiation, the relationships were similar to those previously described for the chick.     

Effects of neuromuscular activity on choline acetyltransferase and acetylcholinesterase

Regeneration of the amputated hind limb of the salamander was prevented by the injection of methadone or levorphanol. Blastema failed to develop despite formation of a thick epidermal cap at the wound site. Injection of the narcotic antagonist, levallorphan, blocked blastemal development for 4 wk but normal growth then began. Phalanges appeared 4 wk later than in controls. Naloxone, a potent narcotic antagonist without agonist activity, neither altered blastemal development nor prevented normal regeneration and differentiation. Treatment with the opioids methadone or levorphanol produced some atrophy of the lingual epithelium and taste buds of the salamanders. Neither of the antagonists caused these changes.     

Choline acetyltransferase and acetylcholinesterase in muscular dystrophic mice

The activities of choline acetyltransferase (CAT) and acetylcholinesterase (AChE) were assayed in various tissues of dystrophic (dy/dy) and normal mice of Bar Harbor strain 129. The brain weights of these dystrophic mice were not significantly different from those of normal mice, but the average body weight of these dystrophic mice was only 66.8% of that of the controls. The activity of CAT (expressed as unit activity per mg of protein) was very similar in the brains of both groups of animals, but the CAT activity (per mg of protein) in the hindlimb muscles of the dystrophic mice was significantly higher than that of the controls. The patterns of AChE activity, as separated by sucrose density gradient centrifugation, were distinctly different in extracts of dystrophic and normal muscle. Compared with controls, decreased activity of the 15-S and 10-S forms of AChE, with increased activity of a 4.3-S forrn of AChE, was observed in dystrophic muscle.     

Increase in nerve growth factor-like immunoreactivity and decrease in choline acetyltransferase following contusive spinal cord injury

We have previously described a graded spinal cord injury model in the rat. Mild contusive injury results in an initially severe functional deficit that is attenuated over time to reveal the mild chronic deficits that characterize this injury. In this study, we have shown that mild contusive injury also results in a significant decrease in choline acetyltransferase (ChAT) activity during the first week after injury. At 1 week ChAT activity is maximally reduced at the site of the contusion and is also significantly lowered throughout the spinal cord. ChAT activity then rebounds during the following 3 weeks, partially at the injury site where there is considerable loss of gray and white matter, and completely in rostral and caudal cord segments. The rebound in ChAT activity is temporally associated with the partial recovery of function. Further, the changes in ChAT activity after injury are mirrored by changes in nerve growth factor-like immunoreactivity (NGF-LI) as determined by a specific two-site ELISA. NGF-LI increases significantly after injury, reaching a maximum at 7 days after contusion and at the injury site. However, levels of NGF-LI are also significantly increased throughout the spinal cord. NGF-LI then decreases at 2 and 4 weeks as ChAT activity rebounds. Further experiments will be needed to examine the possibility of a role for NGF in promoting the recovery of function after spinal cord injury.     

Increased activity of choline acetyltransferase and acetylcholinesterase in actively epileptic human cerebral cortex

We measured the activities of the cholinergic marker synthetic and catabolic enzymes choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) in surgical specimens obtained from 38 patients immediately following anterior temporal lobectomy for intractable epilepsy. Samples from patients with actively spiking lateral temporal cortex were compared to non-spiking lateral temporal cortex obtained from patients in whom the epileptic discharges were confined to the hippocampus. Mean activities of ChAT and AChE were increased by 25% (P less than 0.01) and 30% (P less than 0.025) respectively in the spiking vs. non-spiking cortex. We suggest that the above-normal activity of these cholinergic marker enzymes may reflect sprouting of cholinergic nerve terminals in spontaneously spiking cortex of some patients and/or increased acetylcholine metabolism secondary to the stimulatory effect of the ongoing epileptic discharge.     

Axonal transport of norepinephrine and choline acetyltransferase in regenerating sciatic nerve of the rat.

Axonal transport of norepinephrine (NE) and choline acetyltransferase (ChAc) in the distal portion to the transected and sutured region in the rat sciatic nerve was investigated together with correlations of the contractility of the reinnervated gastrocnemius-plantaris muscle. In the fluorescence histochemical study, the initial delay and the rate of regeneration of noradrenergic fibers were found to be approximately 2 days and 4 mm/day, respectively. In the regenerating nerves, the accumulation of ChAc was about one-half that of normal at 4 weeks and returned to normal at 12 weeks. The amplitude of muscle contraction induced by stimulation of the sciatic nerves was one-half that of normal at 4 weeks and recovered to normal at 12 weeks. The accumulation of NE was still one-fourth that of normal at 12 weeks, and catecholamine fluorescence in the sural artery was still weak, fine, and scattered, compared to that in the artery innervated by the normal sciatic nerve. These results indicate that the function of cholinergic motor fibers correlates with the accumulation of ChAc and that the recovery in amount of transportable NE in the sciatic nerve is much slower than that of the cholinergic component.     

Choline acetyltransferase, choline kinase, and acetylcholinesterase activities during the development of the chick ciliary ganglion

The specific activity of choline acetyltransferase, choline kinase, and acetylcholinesterase was measured in ciliary ganglia of chick embryos from 9 days of incubation to hatching. The specific activity of choline acetyltransferase increased eightfold during this period and the activity per cell increased from 29.5 fmol/hr/cell at 9 days to 2428 at hatching. The specific activity of both choline kinase and acetylcholinesterase was highest at 9 days of incubation although the total activity per ganglion increased nearly six- and eightfold, respectively, during the developmental period studied. The specific activity of choline acetyltransferase in the choroid cells was significantly higher than that in the ciliary cells after 16 days of incubation, with values of 767 and 589 μmol/g dry weight/hr, respectively, at 20 days of incubation. When correlated with the morphological and physiological development, the results of this study indicate that relatively low levels of acetylcholine synthetic capacity (29.5 fmol/hr) are sufficient for a functional cholinergic synapse. The major increase in choline acetyltransferase activity parallels synaptic maturation and the establishment of functional connections by the postganglionic neurons with the peripheral field.     

Choline acetyltransferase and acetylcholinesterase activities in muscles of aged mice

The activities of choline acetyltransferase (CAT) and acetylcholinesterase (AChE) were assayed in intact diaphragm, extensor digitorum longus (EDL), and soleus muscles or their homogenates of young (2-6 months) and aged (24-34 months) mice. CAT activity (per mg of protein) was significantly higher in diaphragm and soleus of old mice in comparison with the young but the age change in EDL was negligible. On the other hand, AChE activity (per mg of protein) was significantly higher in EDL of old mice but in diaphragm and soleus muscles the enzyme activity did not show any significant change statistically. The diaphragm muscle was divided into two fractions, one being neuromuscular (NM) fraction and the other the remainder of the muscle (M fraction). No appreciable change in the ratio of the enzyme activities of NM fraction to the one of M fraction was obtained between the young and aged preparations. Thus, it seems likely that there is an age-related change in CAT and AChE activities which might be affected by the degree to which muscle activity is maintained.     

局部缺血坐骨神经相关神经元胞体乙酰胆碱酯酶变化的定量分析

BACKGROUND： Peripheral nerve ischemia has been shown to result in ischemic fiber degenera-tion and axoplasmic transport disturbance. However, the effect on acetylcholinesterase （AChE） ex- pression in relevant cells following sciatic nerve ischemia remains unclear.
OBJECTIVE： To observe AChE concentration changes following peripheral nerve ischemia.
DESIGN, TIME AND SETTING： The present comparative observation, neuroanatomical experiment was performed at the Central Laboratory Animal of Chengde Medical College between 2006 and 2007.
MATERIALS： A total of 20 healthy, adult, Wistar rats were randomized into two groups （n = 10）： 8-day ischemia and 14-day ischemia.
METHODS： Ischemia injury was induced in the unilateral sciatic nerve （experimental side） through ligation of the common iliac artery. The contralateral side received no intervention, and served as the control side. Rats in the 8-day ischemia and 14-day ischemia groups were allowed to survive for 8 and 14 days, respectively.
MAIN OUTCOME MEASURES： The L5 lumbar spinal cord and the L5 dorsal root ganglion were removed from both sides and sectioned utilizing a Leica vibrating slicer. AChE cellular expression was detected using Karnovsky-Root, and the number of AChE-positive cells and average gray value were analyzed using a MiVnt image analysis system.
RESULTS： In the 8-day ischemia group, AChE-positive cell numbers were significantly less in the dorsal root ganglion and spinal cord anterior horn of the experimental side, but the average gray value was significantly greater, compared with the control side （P 〈 0.05）. These changes were more significant in the 14-day ischemia group than in the 8-day ischemia group （P 〈 0.01）.
CONCLUSION： Peripheral nerve ischemia leads to decreased AChE expression in the associated cells in a time-dependent manner.     

Aβ1～42对不同年龄组大鼠ChAT和AchE活性变化的实验研究

目的 观察大鼠海马注射Aβ1～42后行为学习记忆和ChAT、AchE活性的变化情况。方法 采用Y迷宫测试行为学习记忆情况和比色法测定ChAT、AchE活性变化。结果 成年、老年模型组出现了行为学习记忆障碍,同时基底前脑ChAT活性降低（P〈0．05）,而海马AchE活性变化不明显（P〉0．05）。幼年模型组基底前脑ChAT活性变化不明显（P〉0．05）,但海马区AchE活性降低（P〈0．05）。结论 ChAT活性的变化在Aβ机制中起重要作用,提高ChAT活性是治疗AD的靶点之一。     

Topochemical localization of choline acetyltransferase and acetylcholinesterase in mouse brain

We provide evidence that callosal projections within the primary somatosensory cortex of the rat are distributed in a detailed pattern which is complementary to the pattern of specific thalamocortical projections to this cortical region.     

trkB-like immunoreactivity in rat dorsal root ganglia following sciatic nerve injury

The expression of full-length trkB protein, the functional high affinity receptor for BDNF and NT-4, was examined by immunohistochemistry in adult rat L4–L5 dorsal root ganglia after different types of sciatic nerve lesions. In normal ganglia, 52.5% of the neurons showed trkB-like immunoreactivity. Size measurements demonstrated that trkB-like immunoreactivity was seen predominantly in small- and medium-sized cells. This was confirmed by the finding that 28% of all trkB-positive neurons showed affinity to RT97, an antibody which lanels a neurofilament epitope specific for medium-sized and large primary afferent neurons. After crush, section or neuroma formation of the sciatic nerve, the proportion of trkB-positive cells was 64.5%, 58% and 61.9%, respectively. Since trkB-receptors are present in regenerating primary afferent neurons, these data could indicate that BDNF and/or NT-4 are involved in sensory nerve fiber regeneration after adult injury.     

Astrocytes in the aged rat spinal cord fail to increase GFAP mRNA following sciatic nerve axotomy

Aging in the brain is associated with specific changes in the astrocyte population. The present study establishes that similar changes occur in the aging spinal cord. The levels of glial fibrillary acidic protein (GFAP) mRNA were significantly increased 0.4-fold in aged 8- to 17-month-old rats compared to young 2-month-old rats. The ability of astrocytes in the aging spinal cord to respond to a non-invasive CNS injury was compared to young rats 4 days following sciatic nerve axotomy. The level of GFAP mRNA was significantly increased 0.5-fold in the young rats in response to axotomy. In contrast, the level of GFAP mRNA in aged rats did not increase following injury above that present in non-axotomized rats of the same age.     

Compensatory projection of primary nociceptors and c-fos induction in the spinal dorsal horn following neonatal sciatic nerve lesion

The sciatic nerve was cut in newborn rats, and prevented from regenerating for 8 weeks. The number of dorsal root ganglion (DRG) neurons in L4 and L5, the distribution of central axon terminals of primary nociceptors, and the activity of secondary nociceptors were examined in the lumbar dorsal horn. The neonatal sciatic lesion caused about 60% reduction of DRG neurons. The central terminal field of the sciatic primary nociceptors negatively labeled by in situ binding of Bandeiraea simplicifolia isolectin B4 (BsIB4) markedly shriveled. Instead, the central representation of the saphenous nerve and the posterior cutaneous nerve of the thigh (PC) expanded. The laminae I/II neuropil in the medialmost (1/4) of the L3 dorsal horn and in the second lateral (1/4) around the L4/5 junction was occupied by the BsIB4 binding sites derived from the saphenous and the PC primary neurons, respectively. Noxious stimuli applied to the receptive fields of the saphenous and the PC nerves induced c-Fos-like immunoreactivity in many neurons in the expanded central terminal fields of the nerves. The collateral sprouts of uninjured primary nociceptors did not only invade the deafferented area of the dorsal horn but also established functional synaptic connections.     

Choline acetyltransferase activity in the nucleus tractus solitarius: Regulation by the afferent vagus nerve

The influence of nodose ganglionectomy or transection of the peripheral branches of the afferent vagus nerve on choline acetyltransferase (ChAT) activity in the nucleus tractus solitarius (NTS) was studied. ChAT activity was reduced in the microdissected caudal and intermediate portions of the NTS in vagotomized as well as ganglionectomized rats. However, only the ganglionectomy resulted in the degeneration of medullary nerve fibers. These results suggest that the changes in ChAT activity in the NTS are independent of neuronal degeneration and may be due to transynaptic modulation of ChAT activity by afferent vagal impulses. The presence of ChAT in the sensory nodose projection to the NTS, however, cannot be ruled out.     

Transport of choline acetyltransferase and acetylcholinesterase in the central stump and isolated segments of a peripheral nerve.

Axonal transport of choline acetyltransferase (ChAc, E.E.:2.3.1.6) and acetyl cholinesterase (AChE, E.C.:3.1.1.7) was studied in the peroneal fascicles of rabbit sciatic nerves. The accumulation of ChAc in the central nerve stump proceeded 5 times more slowly than that of AChE and occurred at a distanct of 2-4 mm proximally from the end, whereas AChE accumulated in the last 2 mm of the stump. In double-ligated segments of the nerve in situ the activity of ChAc decreased at the proximal and increased at the distal end; the activity of AChE rose at both ends, The increase of ChAc activity did not cease until 22 h, whereas that of AChE stopped before 10 h. The intensity of ChAc transport is considerably diminished in the part of axon separated from the nerve cell body. Differences between the behavior of ChAc and AChE are interpreted by the assumption that the axonal transport of ChAc is slow, unidirectional, concerns all of the enzyme in the nerve, and that most of the transported enzyme is not associated with intraaxonal organelles. In contrast to ChAc, the transport of AChE is fast, bidirectional, and concerns a minor proportion of enzyme in the nerve; the transported enzyme is associated with organelles. The rate of proximodistal transport of ChAc is estimated at 4 mm/day (based on the assumption that 100% of the enzyme moves proximo-distally) and that of AChE at 480 mm/day (based on the extimate that 5% of enzyme moved proximo-distally in the present experiments).     

Development of cholinergic markers in mouse forebrain. I. Choline acetyltransferase enzyme activity and acetylcholinesterase histochemistry

Measurements of choline acetyltransferase (ChAT) activity were made during the development of the neocortical cholinergic innervation, and correlated with the development of the acetylcholinesterase (AChE) staining pattern in mouse cerebral cortex and several other areas of the forebrain between the time of initial onset and maturity ChAT activity can first be measured on postnatal day 6 (P6). The enzyme reaches 40% of adult activity by P18 and adult values by 7 weeks postnatal. The onset of AChE staining varies for different regions of the forebrain and for various areas within the cerebral cortex. The earliest appearance of AChE is seen in several basal forebrain nuclei including the striatum, the ventromedial region of the globus pallidus and the hypothalamus on embryonic day 18 (E18). In neocortex and olfactory cortex, AChE-stained axons are seen in the white matter before birth, but do not enter cingulate cortex and hippocampus until P2. By P2. almost all areas of the basal forebrain and diencephalon have acquired some AChE staining pattern. The adult distribution of AChE staining is reached by 3 weeks postnatal in all areas of the forebrain. Adult cerebral cortex shows a characteristic pattern of alternating AChE dense and AChE sparse bands which vary in depth depending on the cortical area. The cortical banding pattern develops in an 'inside-out' fashion, starting in layer VI and gradually entering more superficial layers. In parallel with the AChE pattern of development in cortex, transient AChE staining can be observed in some thalamic nuclei and in some forebrain fiber systems. In the neostriatum patches of intense AChE staining first develop along the ventrolateral border, then spread throughout the whole nucleus and finally coalesce to a uniform high density over the entire neostriatum. We discuss the close spatial and temporal correspondence between AChE pattern development and reported data on synapse formation, and speculate on the role of the cortical cholinergic system in development.