Quantitative immunohistochemical distribution of choline acetyltransferase in the rostral forebrain of the rat

Alterations in cognitive function in prepubertal mice with protein malnutrition: Relationship to changes in choline acetyltransferase

We have found that protein malnutrition (PM) causes a significant impairment of memory-related behavior on the 15th and 20th day after the start of PM (5% casein) feeding in prepubertal mice but not in postpubertal mice, as measured by a passive-avoidance task. This impairment was almost completely reversed by merely switching to a standard protein (20% casein) diet on the 10th day after the start of PM. However, the reversal was not observed when the switching to a standard protein regimen was done on the 15th day of the PM diet. Interestingly, the impairment of memory-related behavior on the 20th day was improved by the chronic administration of physostigmine (0.1 mg/kg/day x last 10 days, i.p.), a cholinesterase inhibitor. To correlate brain cholinergic neuron function with the memory-related behavior impairment induced by PM, microphotometry was used to determine the histological distribution of the imunofluorescence intensity for choline acetyltransferase (ChAT), a functional marker of presynapse in cholinergic neurons. The change in the intensity of fluorescence indicated that ChAT protein was decreased in the hippocampus (CA1, CA3 and dentate gyrus) on the 20th day after PM feeding in comparison with controls. These results suggest the possibility that the memory-related behavior deficits observed in prepubertal mice with PM are caused by a dysfunction of the cholinergic neurons in the hippocampus.

Characteristics of changes in cholinergic function and impairment of learning and memory-related behavior induced by olfactory bulbectomy

Memory function after olfactory bulbectomy (OBX) was examined in two tasks, namely, step-through passive avoidance task and elevated plus-maze task. OBX mice showed a significant impairment of learning and memory-related behavior on the 7th and 14th day, as measured by passive avoidance task but not elevated plus maze task. The impairment of learning and memory-related behavior on the 14th day was improved by administration of the cholinesterase inhibitor physostigmine (0.1 mg/kg, i.p.), the non-selective muscarinic agonist oxotremorine (0.1 mg/kg, i.p.) or the selective muscarinic M(1) agonist McN-A-343 (10 microg/mouse, i.c.v.). In contrast, administration of the nicotinic agonist lobeline (5-9.8 mg/kg, i.p.) or the selective muscarinic M(2) antagonist methoctramine (2.25-18 microg/mouse, i.c.v.) has no effect on the impairment of learning and memory-related behavior induced by OBX. In addition, we have demonstrated that the intensity of choline acetyltransferase (ChAT) fluorescence is significantly decreased in the cortex, hippocampus and amygdala on the 14th day after OBX. These results suggest that the impairment of learning and memory-related behavior induced by OBX may be caused by degeneration of cholinergic neurons and muscarinic M(1) receptors play an important role in the improvement process.

Comparison analysis of distributions of tyrosine hydroxylase, calmodulin and calcium/calmodulin-dependent protein kinase II in a triple stained slice of rat brain

The immunohistochemical distributions of tyrosine hydroxylase (TH), calmodulin (CaM) and calcium/CaM-dependent protein kinase II (CaMKII) in the rat forebrain were compared quantitatively to confirm our previous finding that TH activity and dopamine synthesis in the brain are regulated by a calcium/CaM-dependent system. The same slice was triply stained and the above substances were detected immunohistochemically. Their distributions in the slice were measured using a brain mapping analyzer which is a microphotometry system for the analysis of the distribution of neurochemicals in a large tissue slice. Each coronal section was divided into approximately 250000 to 310000 microareas at 20-microm intervals, and the immunohistochemical fluorescence intensities of the three substances in these microareas were analyzed independently. Quantitative images of the distributions were reconstructed from the data, and the distribution of each substance was investigated. Immunoreactive staining of TH, CaM and CaMKII was observed in almost all areas of the brain, but the intensities varied. Markedly intense TH-, CaM- and CaMKII-like immunoreactivities were distributed in the anterior dorsolateral and posterior areas of the neostriatum, nucleus accumbens and olfactory tubercle. In the previous study, the amount of dopamine was increased by the intracerebroventricular administration of calcium chloride in the neostriatum and nucleus accumbens. Combining these results with those previously reported, it is suggested that TH activity and dopamine synthesis in these regions are regulated by calcium ions via CaM and CaMKII. This method is a powerful technique for quantitative and comparative analysis of the distributions of various neurochemicals in the same slice, and we believe that it will facilitate investigation of the functions of the central nervous system and disorders thereof in various diseases.

Immunohistochemical estimation of brain choline acetyltransferase and somatostatin related to the impairment of avoidance learning induced by thiamine deficiency

We have found that thiamine-deficient (TD) rats show significant impairment of avoidance learning on the 25th day after the start of TD diet, as measured by passive-avoidance task. Administration of physostigmine (0.1 mg/kg, i.p.) from the 14th day after the start of TD diet improved the impairment of avoidance learning to the pair-fed (PF) control level by the 25th day. However, the recovery effect of physostigmine did not occur on the 25th day when the treatment was begun on the 21st day. To ascertain the correlation between the cholinergic neuronal function in rat brain and the avoidance learning impairment induced by TD, the immunohistochemical distribution of brain choline acetyltransferase (ChAT) was determined by fluorescence intensity using two-dimensional microphotometry. The intensity of the ChAT fluorescence started to decrease in the cortex and hippocampus on the 14th day and showed a marked decrease in the cortex, hippocampus and thalamus on the 25th day of TD feeding in comparison with PF controls. The intensity of the somatostatin (SST) fluorescence was unchanged on the 14th day of TD feeding, but on the 25th day, SST was significantly decreased in comparison with PF controls. Furthermore, physostigmine treatment from 14th day after the start of TD diet reversed SST fluorescence intensity to the control level by the 25th day. These results suggest that the impairment of avoidance learning induced by TD may involve not only cholinergic but also somatostatinergic systems.

Quantitative imaging of substance P in the human brain using a brain mapping analyzer

The distribution of substance P (SP)-like immunoreactive neurons in the brains of aged normal human was analyzed quantitatively. Consecutive coronal sections in which the striatum and the substantia nigra were exposed widely, were obtained from the right hemisphere and stained immunohistochemically for SP. Each stained section was divided into approximately three million microareas and the immunohistochemical fluorescence intensity in each area was measured using a human brain mapping analyzer, which is a microphotometry system for analysis of the distribution of neurochemicals in a large tissue slice. These distributions are displayed in color and monochromatic graphics. In the analyzed brain regions, conspicuously intense SP-like immunoreactivity was observed in the substantia nigra and the internal segment of the globus pallidus. Within the substantia nigra, the SP-like immunoreactive intensity in the pars compacta was 25%, higher than that in the pars reticulata, and the distribution of melanin-containing neurons corresponded well to the distribution of the SP-containing structures. SP-like immunoreactive intensity in the internal segment of the globus pallidus, which was lower than that in the substantia nigra, was approximately twice as high as that in the external segment of the globus pallidus. Very intense immunoreactivity was localized at the most medial area of the internal segment of the globus pallidus. The SP-like immunoreactive intensity in the caudate nucleus and putamen was moderate, and the distribution was heterogeneous and observed in patches.

Quantitative mapping analyzer for determining the distribution of neurochemicals in the human brain

We developed a human brain mapping analyzer to determine the quantitative distribution of specific molecules, such as neurotransmitters or neuromodulators, based on a fluorescence microphotometry system that we had previously developed. The immunohistochemical fluorescence emitted from each microarea of a brain slice is collected into a photomultiplier tube through the pinhole and objective lens of a microscope. The brain slice is moved in the x- or y-direction by a motorized scanning stage under the objective lens, and the fluorescence intensities are measured quantitatively. The scanning speed is approximately 100 microareas/s, the maximum stage motion is 150 x 150 mm, and an unlimited amount of data can be gathered continuously by transfer to external memory devices. In this paper, this analyzer is characterized in detail, and the methods used for the preparation and analysis of human brain slices are described. As an example, the cholinergic distribution in hemispheric coronal slices of the adult human brain is analyzed. Each slice, immunohistochemically stained for choline acetyltransferase, was divided into approximately 3 million microareas (one area is 50 microm in diameter), and the distribution of the cholinergic neurons is shown.

Changes in choline acetyltransferase activity and distribution following incomplete cervical spinal cord injury in the rat

Incomplete cervical spinal cord injuries were produced in rats by placing 10 g or 20 g weight on exposed dura at the C6 level for 5 min (Mild or Moderate injury). These two degrees of the injury resulted in initial motor functional deficits, followed by recoveries. In this study, changes in choline acetyltransferase activity and distribution following the incomplete cervical cord injuries were investigated using radioenzyme assay, and fluorescence microphotometry. We demonstrated that mild injury led to a transient decrease of choline acetyltransferase activity in the compressed spinal cord segment, but showed almost no histologic change at two days after injury. Although a low level of choline acetyltransferase immunofluorescence was found in the ventrolateral anterior horn at two days after injury, it recovered completely by one week after injury. These findings suggest that there was a strong correlation between the transient motor functional deficit and the decrease in choline acetyltransferase activity following mild injury. Moderate injury resulted in persistent low level of choline acetyltransferase activity in the compressed spinal cord segment accompanied by a striking loss of gray matter. On the other hand, at seven, 14 and 28 days after injury, over-expression of choline acetyltransferase activity was found in the neighboring spinal cord segments located both rostral and caudal to the injury, which showed no histologic change. In addition, excessively high levels of choline acetyltransferase immunofluorescence were found in the ventrolateral anterior horn of these segments. A strong correlation was found between the motor functional recovery and the late, excessive high levels of choline acetyltransferase activity in the neighboring regions. These results suggest that cholinergic neurons, especially spinal motor neurons may play an important role in the motor functional recovery following incomplete cervical spinal cord injury.

Changes in choline acetyltransferase distribution in the cervical spinal cord after reversible cervical spinal cord injury

Reversible spinal cord injury (SCI) at C6 level in rats, produced by the weight-placed method, resulted in a severe motor functional deficit initially, followed by a gradual recovery. During the recovery, choline acetyltransferase (CAT) distribution in the cervical spinal cord was investigated at 2, 4, 7, 14 and 28 days after the injury by quantitative immunohistochemistry with a fluorescence microphotometry system. At C6 level, the fluorescence intensity of the ventrolateral anterior horn (VLAH), which reflected the concentration of CAT, decreased to approximately 50% of that of the sham-operated group at 2 days. It then recovered to 60% at 4 days after the injury, and remained unchanged thereafter. Fluorescence intensities in VLAH at C4-5 and C7-8 levels decreased to approximately 60-70% at 2 days after the injury, but it recovered and increased to 110-130% thereafter.

Quantitative analysis of immunohistochemical distributions of cholinergic and catecholaminergic systems in the human brain

The distributions of the cholinergic system and catecholaminergic system in the normal human brain were analysed quantitatively by a microphotometry system. Consecutive coronal sections were obtained from the anterior area of the left hemisphere and were stained alternately with fluorescent immunohistochemical staining for choline acetyltransferase or tyrosine hydroxylase. Each stained section was divided into approximately 120,000 areas and the fluorescence intensity in each area was measured by a fluorescence microphotometry system which is a measuring microscope for distribution of fluorescence intensity in the tissue slice. Nonspecific autofluorescence was distributed in myelinated nerve fiber throughout the entire area, which was subtracted from the fluorescence intensity value in each measuring area. The obtained immunohistochemical fluorescence intensities of choline acetyltransferase and tyrosine hydroxylase were classified into eight ranks and were indicated by color graphics. Also, the intensity values of actual immunohistochemical fluorescence in the various brain regions were presented. The choline acetyltransferase and tyrosine hydroxylase concentrations varied greatly depending on the brain region. Relatively high levels of choline acetyltransferase and tyrosine hydroxylase were distributed in the putamen, caudate nucleus, claustrum, insula and some cortical regions. The immunohistochemical level of tyrosine hydroxylase was lower than that of choline acetyltransferase in a few brain regions such as the globus pallidus and amygdala. High levels of choline acetyltransferase and tyrosine hydroxylase were localized in the one area of the basal ganglia which developed from the telencephalic area, whereas middle levels of these were distributed in another, part of which developed from the diencephalic area.(ABSTRACT TRUNCATED AT 250 WORDS)