Differential effects of corticotropin-releasing hormone on central dopaminergic and noradrenergic neurons

Corticotropin-releasing hormone (CRH) has been shown to be a central mediator for most, if not all, stress-induced responses. Since stressful stimuli may decrease hypothalamic tuberoinfundibular and tuberohypophysial dopaminergic neuronal activities, we aimed to determine whether CRH is involved. Using central administration of various doses of ovine CRH (oCRH; 1, 3 and 10 µg/rat) into the lateral cerebroventricle of either male or female rats, the neurochemical changes in various parts of the central nervous system, including the hypothalamus, were determined by high-performance liquid chromatography at various times after the injection (30, 60, 120 and 240 min). The concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC) and 3-methoxy-4-hydroxy-phenylethyleneglycol (MHPG), two major metabolites of dopamine and norepinephrine, respectively, in discrete brain regions were used as indices for catecholaminergic neuron activity. Plasma corticosterone levels increased significantly after all doses of oCRH and at all time points studied. oCRH also exerted significant stimulatory effects on noradrenergic neuron terminals in the frontal cortex, and on dopaminergic neuron terminals in the nucleus accumbens, hypothalamic paraventricular and periventricular nuclei, and intermediate pituitary lobe. Dopaminergic neuron terminals in the median eminence and the neural lobe of the pituitary, however, were not affected. There was no major difference in the responses between male and female rats. We conclude that CRH has a differential effect on central catecholaminergic neurons.     

c-fos expression in the amygdala:In vivo antisense modulation and role in anxiety

Summary 1. The amygdaloid complex is a key structure in mechanisms of fear and anxiety. Expression of the immediate-early gene c-fos has been reported in the central nucleus of the amygdala following various stressors, but the functional role of this phenomenon has remained unknown.2. c-fos expression was observed in the central nucleus when rats were subjected to a pharmacologically validated animal model of anxiety, the Vogel conflict test, but not after mere exposure to the test apparatus. Bilateral amygdala injection of a 15-mer phosphorothioate c-fos antisense oligodeoxynucleotide prior to testing blocked conflict-induced c-fos expression and had behavioral effects similar to those of established antianxiety drugs.3. Separate experiments determined that antisense treatment did not affect conflict behavior by acting on shock thresholds or drinking motivation.4. These findings provide evidence that neuronal activation and c-fos induction in the amygdala may be of importance for mechanisms of fear and anxiety.     

Calcium and calcium-binding proteins in the nucleus

Calcium has long been known to play a role as a key cytoplasmic second messenger, but until relatively recently its possible involvement in nuclear signal transduction and the regulation of nuclear events has not been extensively studied. Evidence revealing the presence of transmembrane nuclear Ca²⁺ gradients and a variety of intranuclear Ca²⁺ binding proteins has fueled renewed interest in this key ion and its involvement in cell-cycle timing and division, gene expression, and protein activation. This review will offer an overview of the current state of knowledge and theory regarding calcium orchestration of nuclear functions and events and discuss possible future directions in this field of study.     

The Effect of Old Age on the Free-Running Period of Circadian Rhythms in Rat

The free-running period is regarded to be an exclusive feature of the endogenous circadian clock. Changes during aging in the free-running period may therefore reflect age-related changes in the internal organization of this clock. However, the literature on alterations in the free-running period in aging is not unequivocal. In the present study, with various confounding factors kept to a minimum, it was found that the free-running periods for active wakefulness, body temperature, and drinking behavior were significantly shorter (by 12-17 min) in old than in young rats. In addition, it was found that the day-to-day stability of the different sleep states was reduced in old rats, whereas that of the drinking rhythm was enhanced. Transient cycles were not observed, nor were there any age-related differences in daily totals of the various sleep-wake states. The amplitudes of the circadian rhythms of active wakefulness, quiet sleep, and temperature were reduced, whereas those of paradoxical sleep and quiet wakefulness remained unchanged.     

谷子显性雄性不育基因“Ms~（ch）”的细胞质转换

通过种间杂交和连续置换回交,选育出具有轮生狗尾草（Ｓ,ｖｅｒｔｉｃｉｌｌａｔａ（Ｌ．）Ｂｅａｕｖ．）细胞质的谷子（Ｓｅｔａｒｉａｉｔａｌｉｃａ（Ｌ．）Ｂｅａｕｖ．）核质杂种,以带有上位基因Ｒｆ的显性核不育植株为父本与此核质杂种杂交,已将显性核不育基因导入轮生狗尾草细胞质中,从其分离后代中选出了具有显性核不育基因的新核质杂种,为谷子的三系选育和细胞质研究创造了新工具,也为核互作杂优利用增加了核质互作优势新机制。     

陕西关中小麦品种更替中性状演变及其发展方向

以关中地区四十年代到九十年代推广种植的主要代表品种及品系为材料,对其分蘖动态、生育期、株高因素、穗部性状、产量、生物学产量、经济系数及冬春性等２０个性状进行了研究,其结果表明关中地区四十代到九十年代小麦品种性状演变的趋势是：冬、春季分蘖变化不大,冬季分蘖趋向略增;春季分蘖趋向略减;成穗数趋向降低,拨节,抽穗和开花期有趋早倾向,而成熟期和总生育天数无明显变化,株高降低极明显（１３７．７－８５．２ｃｍ     

Selective Axonal Argentaffin Staining in Rat Central Nervous System after Protein Mercuration

The mercury-silver (Hg-Ag) argentaffin technique, known to stain specifically proteins in the lateral components of triads/diads in striated muscle cells, was applied to the central nervous system of adult rats. Following fixation in glutaraldehyde, axons in white and gray matter were selectively stained, but not perikarya or their proximal axon and dendrites. Neural tissues were postfixed 24 hr in 5% (w/v) mercuric acetate in 2% (v/v) acetic acid in distilled water, stained for 12-24 hr in darkness at 37-43 C with ammoniacal silver nitrate solution, freshly prepared by adding concentrated ammonia to 60% (w/v) silver nitrate solution until a small amount of silver oxide precipitate remained undissolved. Samples were then washed with freshly prepared 5% (w/v) sodium sulfite and distilled water. All steps were carried out using dark-colored glass flasks. Samples were dehydrated with ethanol and embedded in Paraplast or Poly Bed. Electron microscopy showed the silver-reducing protein inside the axons. Methylation abolished Hg-Ag axonal reactivity indicating that carboxyl groups were necessary for silver staining. Proteins with solubility properties characteristic of neurofilament proteins were involved in Hg-Ag staining. In the cerebellum the plexus of parallel fibers in the molecular layer were not stained, while basket cell axonal processes reacted intensely. The method appears to distinguish neuronal protein variants related to cytotypic differences in cytoskeletal neurofilaments.     

Newly established cell lines fromDrosophila larval CNS express neural specific characteristics

Summary From the central nervous system ofDrosophila melanogaster 3rd instar larvae, eight continuous cell lines have been established (named ML-DmBG1 to 8). Using ML-DmBG2, single colony isolation was carried out and six colonial clones were obtained. All reacted to the antibody to horseradish peroxidase, which is a neuronal marker in insects. Acetylcholine, a known neurotransmitter inDrosophila, was detected in three of the colonial clones by high performance liquid chromatography. Therefore, it is concluded that the established colonial clones are neural cells originating in the larval central nervous system. Among them, some variation was observed with respect to morphology, acetylcholine content, and reactivity to anti-HRP. The variation may reflect the heterogeneity of cells composing the central nervous system.     

Evidence for a GABAergic Projection from the Dorsal Nucleus of the Lateral Lemniscus to the Inferior Colliculus

Abstract: This study attempts to determine whether the pathways from the guinea pig dorsal nucleus of the lateral lemniscus (DNLL) to the inferior colliculus (IC) use γ-aminobutyric acid (GABA) as a transmitter. Injections of kainic acid (KA) were used to destroy neurons in the left DNLL. Two to 4 days after the injection, Nissl-stained sections through the lesion site showed destruction of the DNLL neurons. The lesions varied in size; 12–100% of the DNLL neurons were destroyed on the injected side without damage to the ipsilateral IC. Two to 4 days after the injection, the electrically evoked, Ca²⁺-dependent release and high-affinity uptake of [³H]GABA were measured in dissected pieces of the left and right IC. These activities were compared with those in the IC taken from unlesioned controls and from sham controls, which received injections of saline instead of KA. Each IC was divided into a dorsal piece, which contained the dorsal cortex and dorsomedial nucleus, and a ventral piece, which contained the central and lateral nuclei. Lesions of the left DNLL depressed the release and uptake of [³H]GABA in the ventral pieces of the IC, but there was a greater depression in the ventral IC contralateral to the lesioned DNLL. There were good correlations between the percentage of neuronal loss in the left DNLL and deficits in [³H]GABA release and uptake activities in the ipsi- and contralateral ventral IC. By contrast, there was no depression of [³H]GABA release and uptake in the dorsal pieces of the IC. The localization of the deficits in release and uptake appears to match the distribution of the synaptic endings of the DNLL pathways in the IC. This correspondence associates GABA release and uptake activities with the DNLL projections to the IC and, therefore, suggests that GABA may be a transmitter of these pathways. The release and uptake of [¹⁴C]glycine was also measured to determine whether glycine might be a transmitter of the DNLL pathways to the IC. Lesions of the left DNLL failed to alter the Ca²⁺-dependent release or the uptake of [¹⁴C]glycine, suggesting that DNLL neurons are unlikely to use this compound as a transmitter.     

Demonstration of melatonin-binding sites in cyclohexylamine-formaldehyde-fixed brain tissues

This study shows for the first time that perfusion of rat or hamster brain with a cyclohexylamine-paraformaldehyde mixture makes possible the observation by autoradiography of melatonin binding sites in structurally well-preserved fixed tissues. This result is a first step in the identification of melatonin-receptor-containing cell types by cytoautoradiography.