Immunocytochemical staining of cholinergic amacrine cells in rabbit retina

Cholinergic neurons of rabbit retina were labelled with an antibody against choline acetyltransferase, the synthesizing enzyme for acetylcholine. Two populations of cells are immunoreactive. Type a cell bodies lie in the inner nuclear layer (INL), their dendrites branching narrowly in sublamina a of the inner plexiform layer (IPL), while type b cell bodies lie in the ganglion cell layer (GCL) with dendrites branching in sublamina b of the IPL. The irregular networks of clustered immunoreactive dendrites are similar, but not identical, in the two sublaminae. Type b cells are more numerous than type a cells in central retina. No axons were stained. It appears that the immunoreactive neurons are normally placed and displaced starburst/cholinergic amacrine cells.     

Intense immunoreactivity for Mn-superoxide dismutase (Mn-SOD) in cholinergic and non-cholinergic neurons in the rat basal forebrain

The immunohistochemical localization of manganese (Mn)-superoxide dismutase (Mn-SOD) was studied in the rat basal forebrain using polyclonal antibodies to Mn-SOD. Neurons of the basal forebrain exhibit a high density of Mn-SOD immunoreactivity. Double immunostaining with a monoclonal antibody to choline acetyltransferase demonstrated that both cholinergic and non-cholinergic neurons in the basal forebrain are intensely immunoreactive for Mn-SOD.     

Intracerebroventricular injection of choline increases plasma oxytocin levels in conscious rats

In the present study, we examined the effect of intracerebroventricularly (i.c.v.) injected choline on both basal and stimulated oxytocin release in conscious rats. I.c.v. injection of choline (50–150 μg) caused time- and dose-dependent increases in plasma oxytocin levels under normal conditions. The increase in plasma oxytocin levels in response to i.c.v. choline (150 μg) was greatly attenuated by the pretreatment of rats with atropine (10 μg; i.c.v.), muscarinic receptor antagonist. Mecamylamine (50 μg; i.c.v.), a nicotinic receptor antagonist, failed to suppress the effect of 150 μg choline on oxytocin levels. Pretreatment of rats with 20 μg of hemicholinium-3 (HC-3), a specific inhibitor of choline uptake into nerve terminals, greatly attenuated the increase in plasma oxytocin levels in response to i.c.v. choline injection. Osmotic stimuli induced by either oral administration of 1 ml hypertonic saline (3 M) following 24-h dehydration of rats (type 1) or an i.c.v. injection of hypertonic saline (1 M) (type 2) increased plasma oxytocin levels significantly, but hemorrhage did not alter basal oxytocin concentrations. The i.c.v. injection of choline (50, 150 μg) under these conditions caused an additional and significant increase in plasma oxytocin concentrations beyond that produced by choline in normal conditions. These data show that choline can increase plasma oxytocin concentrations through the stimulation of central cholinergic muscarinic receptors by presynaptic mechanisms and enhance the stimulated oxytocin release.     

Daily changes in presynaptic cholinergic activity of rat sympathetic superior cervical ganglion

The in vitro capacity of sympathetic superior cervical ganglia (SCG) to take up [³H]choline from the extracellular medium, to synthesize acetylcholine from [³H]choline, and to release [³H]acetylcholine in response to a high K⁺ concentration, were examined in rats throughout a 24-h cycle. Both the release of [³H]acetylcholine and the synthesis of [³H]acetylcholine from [³H]choline exhibited significant diurnal variations, showing maxima during the first half of the night. After these maxima, nocturnal acetylcholine release and synthesis decayed to daytime levels and remained low until the end of the night. [³H]Choline uptake by rat SCG did not vary significantly throughout a 24-h period. A 1.5-h exposure of rats to darkness at the 5th hour of light phase of the daily photoperiod did not change significantly any parameter studied. A 20-min, 5-Hz, electrical stimulation of the preganglionic trunk of SCG excised from rats at noon increased significantly subsequent K⁺-induced [³H]acetylcholine release but did not change [³H]acetylcholine synthesis. In decentralized SCG of rats subjected to a unilateral SCG decentralization and a contralateral sham-operation 7 days earlier, [³H]acetylcholine release and synthesis were highly reduced or abolished at the decentralized side, while [³H]choline uptake remained unaltered. The present results suggest that an activation of preganglionic rat SCG neurons takes place during the first half of the scotophase.     

糖尿病早期肾损害指标的探讨

目的　探讨早期诊断糖尿病肾损害的方法。方法　采用免疫透射比浊法检测尿转铁蛋白 (TF)和尿微量白蛋白(mALB) ,速率法检测尿N 乙酰 B D 氨基葡萄糖苷酶 (NAG) ,Jaffe速率法测尿肌酐。结果　糖尿病患者尿蛋白定性阴性的尿TF、mALB、NAG均较对照组显著增高 (p <0 0 1) ,单项及双项检测TF、mALB、或NAG这三项指标阳性率偏低 ,联合三项检测阳性率可达 91 1%。结论　检测尿中TF、mALB、NAG是诊断糖尿病早期肾损害指标的敏感指标     

Characterization and autoradiographic distribution of hemicholinium-3 high-affinity choline uptake sites in mammalian brain

[3H]hemicholinium-3 (HC-3) binding characteristics have been investigated using membrane binding assays and in vitro receptor autoradiography. In rat brain membrane preparations, [3H]HC-3 binds with high affinity to an apparent single class of sites. [3H]HC-3 binding is Na+-dependent. The ligand selectivity pattern strongly suggests that [3H]HC-3 selectivity labels the high affinity choline uptake (HACU) in brain membranes (HC-3 greater than choline greater than carbamylcholine greater than acetylcholine). This hypothesis is also supported by quantitative autoradiographic data which demonstrate that the discrete distribution of [3H]HC-3 binding sites correlates very well with the known distribution of other cholinergic markers such as choline acetyltransferase (ChAT), acetylcholinesterase (AChE), HACU, and [3H]AH-5183 (blocker of the vesicular transport of acetylcholine). For example, high densities of labelling are observed for these different markers in the interpeduncular nucleus, anteroventral nucleus of the thalamus, striatum, basolateral nucleus of the amygdala, and an exquisite laminar distribution in the hippocampus. Similar autoradiographic distributions of [3H]HC-3 binding sites are observed in other mammalian species such as guinea pig and monkey. Finally, 7-day unilateral kainic acid lesions of the nucleus basalis magnocellularis (nbm) decrease cortical [3H]HC-3 binding and ChAT activity, although not to a similar extent. In summary, these results demonstrate that [3H]HC-3 is a selective ligand of the HACU in mammalian brain. Thus, it is now possible to characterize precisely various structural components of the cholinergic synapses using markers such as [3H]HC-3, ChAT, HACU, [3H]AH-5183, and selective muscarinic and nicotinic receptor radioligands.     

Effects of opiates on the growth of neuron-enriched cultures from chick embryonic brain

Neuron-enriched cultures derived from 6-day-old chick embryo cerebral hemispheres were treated with morphine or methadone, 10(-5) M or 10(-6) M, on days 4-6 or 6-8 in culture and were evaluated morphologically and biochemically at day 9 using phase contrast microscopy and choline acetyltransferase activity (ChAT) as a cholinergic marker. The treatment of the cultures with morphine markedly affected their growth pattern; specifically, we observed an increased number of flat cells presumptively glia, and aggregates sided by flat cells and devoid of thick bundles of neuritic processes that normally characterize neuron-enriched cultures. These morphologic changes were reflected in a drastic decrease of ChAT activity in cultures treated from day 4 to day 6 but not from 6 to 8. In contrast to morphine, exposure to 10(-6) M methadone from day 4 to day 6 resulted in reduced ChAT activity but the growth pattern of the cultures remained morphologically intact. We suggest that morphine exerts a general neurotoxic effect whereas methadone may affect some specific cholinergic function.     

DSP-4, a noradrenergic neurotoxin, produces more severe biochemical and functional deficits in aged than young rats

The present study examines the effects of noradrenergic lesions (either DSP-4 i.p. or 6-hydroxydopamine (6-OHDA) into the dorsal noradrenergic bundle on biochemical (noradrenaline (NA), dopamine (DA), serotonin (5-HT) and choline acetyltransferase (ChAT) activity) and cortical EEG (quantitative EEG (qEEG) and high-voltage spindle (HVS) activity in young and aged rats. Near complete 6-OHDA NA lesions, but not partial DSP-4 NA lesions, increased HVS activity in young rats. DSP-4 and 6-OHDA lesions produced no significant changes in the 5-HT or DA levels or in the ChAT activity in young rats. In some of the aged rats, DSP-4 produced similar biochemical and HVS effects, as it induced in young rats. In the remainder of the aged rats, NA levels were greatly and 5-HT levels slightly decreased. DA levels and ChAT activity were unaltered in either set of aged rats. HVS activity was increased only in that group of aged rats with the greatly lowered NA content. These results suggest that: (1) some of the aged rats are more sensitive to DSP-4 treatment than young adult rats; and (2) NA depletions have to be complete to produce an increase in HVS activity in young and aged rats.     

Decreased [H]hemicholinium binding to high-affinity choline uptake sites in aged rat brain

The binding of [³H]hemicholinium ([³H]HCh-3) to sodium-dependent high-affinity choline uptake sites provides a useful neuroanatomical and functional marker of the cholinergic system. We examined the autoradiographic distribution of [³H]HCh-3 binding sites in the forebrain of young (4–6 months) and old (32 months) rats. There was a widespread reduction of [³H]HCh-3 binding site density in the aged rat brain. This loss presented regional differences with maximal reduction in the medial and posterior striatum (55%) and in the dentate gyrus (47%), in limbic areas such as basolateral amygdala, tubercle olfactorium and piriform cortex the autoradiographic signal was about 25–30% lower. In aged hippocampus and cerebral cortex the density of [³H]HCh-3 binding sites was about 40% lower, the difference between young and senescent animals being less evident in the medial septum and basal nucleus. No significant alterations were observed in interpeduncular nucleus from old rats. These data are in agreement with the functional results obtained by measuring other cholinergic parameters in the aged rat and confirm the vulnerability of cholinergic system during aging     

Relaxation times of choline, creatine and N-acetyl aspartate in human cerebral white matter at 1.5 T

Several studies have investigated the T1 and T2 relaxation time of choline, creatine and N-acetyl aspartate in cerebral white matter in normal human subjects. However, these studies demonstrate a large variation in T1 and T2 values. In the present study, relaxation times of choline, creatine and N-acetyl aspartate were determined in cerebral white matter in 15 control subjects (age 21 +/- 2 y, mean +/- SD) at 1.5 T. Using PRESS, seven or eight data points were obtained to fit the T1 and T2 relaxation curves to, respectively. The mean voxel size was 14 cm3. The T1 relaxation times of choline, creatine and N-acetyl aspartate were 1091 +/- 132 (mean +/- SD), 1363 +/- 137 and 1276 +/- 132 ms. The T2 relaxation times were 352 +/- 52, 219 +/- 29 and 336 +/- 46 ms, respectively.