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.     

Adult outcomes of attention deficit hyperactivity disorder and conduct disorder: are the risks independent or additive?

METHODS: Data were obtained from a longitudinal study sample of 754 adoptees and categorized based on review of the available adoption agency, medical, and psychiatric records of the biological parents. Categorical data were analyzed using chi2 or Fisher's exact tests, as appropriate. Logistic regression analyses were used to assess the relative contribution of variables. RESULTS: There was not a statistically significant difference in the frequency or type of self-reported adult disruptive behavior, arrests, jail stays, felony arrests, or frequency of conduct disorder (CD) when inattentiveness, impulsivity, and hyperactivity were analyzed individually. The contributions of attention deficit hyperactivity disorder (ADHD) were independent and no additional increased risk for future illegal behavior was conferred by the combination of the disorders. While the effect of CD on illegal behavior was correlated with substance abuse and dependence, ADHD continued to be a significant contributor after controlling for substance abuse and dependence. CONCLUSIONS: Data indicated that ADHD and CD are related but different disorders conferring risk for adult illegal behavior or arrest. In this sample, inattention was the most common domain impaired among those with ADHD, followed closely by hyperactivity, with impulsivity reported least often among those endorsing symptoms of ADHD.     

Expression of interleukin-15 in human skeletal muscle – effect of exercise and muscle fibre type composition

The cytokine interleukin-15 (IL-15) has been demonstrated to have anabolic effects in cell culture systems. We tested the hypothesis that IL-15 is predominantly expressed by type 2 skeletal muscle fibres, and that resistance exercise regulates IL-15 expression in muscle. Triceps brachii, vastus lateralis quadriceps and soleus muscle biopsies were obtained from normally physically active, healthy, young male volunteers ( n = 14), because these muscles are characterized by having different fibre-type compositions. In addition, healthy, normally physically active male subjects ( n = 8) not involved in any kind of resistance exercise underwent a heavy resistance exercise protocol that stimulated the vastus lateralis muscle and biopsies were obtained from this muscle pre-exercise as well as 6, 24 and 48 h post-exercise. IL-15 mRNA levels were twofold higher in the triceps (type 2 fibre dominance) compared with the soleus muscle (type 1 fibre dominance), but Western blotting and immunohistochemistry revealed that muscle IL-15 protein content did not differ between triceps brachii, quadriceps and soleus muscles. Following resistance exercise, IL-15 mRNA levels were up-regulated twofold at 24 h of recovery without any changes in muscle IL-15 protein content or plasma IL-15 at any of the investigated time points. In conclusion, IL-15 mRNA level is enhanced in skeletal muscles dominated by type 2 fibres and resistance exercise induces increased muscular IL-15 mRNA levels. IL-15 mRNA levels in skeletal muscle were not paralleled by similar changes in muscular IL-15 protein expression suggesting that muscle IL-15 may exist in a translationally inactive pool.     

Face cooling-induced reduction of plasma prolactin response to exercise as part of an integrated response to thermal stress

Summary This study was designed to verify if the decrease in blood prolactin (PRL) induced by selective face cooling during exercise could be part of a response to specific body thermal stress. Five healthy trained male cyclists presenting a significant plasma PRL elevation to exercise were, on three occasions and at weekly interval, submitted to a submaximal exercise (approx. 65% ) on ergocycle with and without selective face cooling. In absence of face cooling a first trial served to establish reference values for workload, heart rate and plasma PRL levels, the latter increasing markedly (450% of resting values) in these conditions. On a second trial but with workload maintained at reference values (222±9 W), a significant bradycardia was observed with face cooling; furthermore, plasma PRL response to exercise was significantly reduced (to 31% of original response). On a third trial with face cooling, workload had to be significantly augmented (242±10 W) to maintain heart rate at reference level (78%HR _max); in addition, plasma PRL response to exercise was almost unchanged compared to the reference-value level. The absence of a significant face cooling-induced decrease in sympathetic tonus, as evaluated through peripheral plasma catecholamines response, does not indicate a role for the autonomic nervous system in the face cooling-induced reduction of both heart rate and PRL responses during exercise. Assay of circulating peripheral beta-endorphins could indicate that the face cooling-induced PRL blunted response does not necessarily involve an opioid mediation. It was concluded that decreased plasma PRL levels could be associated to bradycardia, hyposudation and peripheral vaso-constriction to constitute an integrated response to face cooling during thermal stress. This study was supported by grants from Natural Sciences and Engineering Research Council of Canada and from Régie de la Sécurité dans les Sports du Québec     

Decreased levels of neuropeptide Y(5) receptor binding sites in two experimental models of epilepsy

It has been suggested that the anticonvulsant effects of neuropeptide Y (NPY) could be mediated by the activation of Y(2) and/or Y(5) receptors. NPY Y(1) receptor levels are known to decrease and Y(2) to increase in rat models of epilepsy. By using an autoradiographic approach, we investigated whether epilepsy models (kainic acid and kindling) are also associated with changes in Y(5) receptors. Compared with naive controls, [125I][Leu(31), Pro(34)]PYY/BIBP3226-insensitive (Y(5)) binding sites in the hippocampus (strata oriens and radiatum of CA3 and CA1) and in the neocortex (superficial layers) were unchanged in sham-stimulated rats, but reduced by approximately 50% in kindled rats (seven days after the last stimulus evokes seizure), and further reduced (to approximately -90%) 1h after a kindled seizure. Additionally, Y(5) receptor binding sites in the hippocampus and in the neocortex were unchanged 6h after kainic acid injection, but were highly reduced at 12 and 24h. No changes in Y(5) binding levels were found in the dentate gyrus and the pyramidal cell layer of the hippocampus.The present data suggest that changes in Y(5) receptor levels occur in epilepsy models. These changes may play a role in seizure expression and/or in the maintenance of kindling hyperexcitability.     

Estrogen effects on object memory and cholinergic receptors in young and old female mice.

We investigated whether object recognition memory is modulated by estrogen in young (5 month) and aged (24 month) female C57Bl/6J mice, and if cholinergic muscarinic receptors might contribute to this response. Mice that were ovariectomized, or ovariectomized plus estradiol-treated three weeks before behavioral testing or quantitative autoradiography were compared to intact mice. Memory for a previously encountered object deteriorated significantly between 3 and 6h after initial exposure, regardless of animal age. In both young and aged mice, estradiol-treated mice showed significantly greater recall than did ovariectomized mice. In both age groups, the apparent number of [(3)H]pirenzepine/M(1)-like and [(3)H]AFDX384/M(2)-like muscarinic receptor binding sites was reduced in the basal forebrain as well as its projection areas following ovariectomy, but this decrease was not alleviated by estrogen. Aging poorly affected object memory, but reduced muscarinic binding in some cortical subregions and in the caudate nucleus. These findings suggest that estrogen effects on memory in C57Bl/6J mice are not due to changes in the number of muscarinic receptors.     

Cloning,sequencing and analysis of the yeastS. uvarum ERG10 gene encoding acetoacetyl CoA thiolase

Summary TheERG10 gene specific toS. uvarum, a brewing yeast, has been cloned by complementation of anS. cerevisiae erg10 mutant.S. uvarum contains two differentERG10 genes. One of these is similar to theS. cerevisiae ERG10 gene; they are structurally different, but functionally homologous. The clonedERG10 gene has been located on chromosome XVI, and we have shown that it is allelic to the previously isolatedtsm0115 mutants. Northern blot and sequence analysis indicate that theERG10 gene is highly expressed, and biochemical and genetic evidence show that it encodes the cytoplasmic acetoacetyl CoA thiolase.     

Acetylcholine release is elicited in the visual cortex, but not in the prefrontal cortex, by patterned visual stimulation: a dual in vivo microdialysis study with functional correlates in the rat brain

By its projections to the primary visual and the prefrontal cortices, the basal forebrain cholinergic system is involved in cognitive processing of sensory stimuli. It has been suggested that visual stimulus-induced cholinergic activation of the visual cortex may exert a permissive role on thalamocortical inputs. However, it is not known if visual stimulation elicits cholinergic activation of high-order brain areas in the absence of attentional need. In the present study, we measured the effects of patterned visual stimulation (horizontal grating) on the release of acetylcholine with dual-probe in vivo microdialysis in the visual and the prefrontal cortices of anesthetized rats. We also used retrograde tracing to determine the anatomical relationships of cholinergic neurons with neurons of the visual system and the prefrontal cortex. Finally, we evaluated a functional correlate of this stimulation, namely c-fos immunolabeling. Patterned visual stimulation elicited significant increases in acetylcholine release in the visual cortex, accompanied by an increased number of c-fos immunoreactive neurons in this brain area. In contrast, in the prefrontal cortex, neither the level of acetylcholine release nor the number of c-fos immunoreactive neurons was significantly changed because of the stimulation. Cholinergic basal forebrain neurons projecting to the visual or the prefrontal cortices were both localized within the horizontal limb of the diagonal band of Broca but were not immunoreactive for c-fos during visual stimulation. No parts of the visual system were found to directly project to these basal forebrain neurons. These results suggest the differential involvement of cholinergic projections in the integration of sensory stimuli, depending on the level of activity of the targeted cortical area.     

Ontogeny of substance P receptor binding sites in rat brain

The ontogeny of substance P (SP) receptor binding sites in rat brain has been studied using both membrane binding assays and in vitro receptor autoradiography. The density of SP binding sites is maximal 1 d before birth and decreases thereafter to reach adult values 14 d after birth. During the early postnatal period, the distribution of SP binding sites undergoes major modifications. For example, very high densities of SP binding sites are present in most brain stem nuclei from 1 to 14 d after birth, while it is not the case in adults. In the striatum, SP receptors are distributed in a "patchy" manner early after birth, while it is much more homogeneous in the adult. This demonstrates that SP receptors undergo major redistributions during postnatal development. The very high density of SP binding sites present in the brain at its early stages of development may indicate that SP could be an important factor involved in the early organization of the CNS.