Dominant-subordinate relationships in castrated male mice bearing testosterone implants

This study tested the hypothesis that subordination in male mice is directly related to reduced levels of circulating testosterone. Several measures of aggressiveness and submissiveness were quantified during or after daily encounters between pairs of intact males, castrated males, or castrated males bearing testosterone implants that were designed to maintain plasma testosterone titers at levels slightly above those of intact males. Behavioral measures included the total amount of fighting that resulted from daily pairing, the tendency for subordinates to fight back, and the relative frequency of urine marking. In all these regards, pairs of testosterone-implanted, castrated males formed dominant-subordinate relationships that involved apparently normal submissive behavior (compared to intact control pairs). Thus we found no evidence that submissive behavior was directly related to a reduction in circulating testosterone titers.     

Beta-endorphin and corticotropin immunoreactivity and specific binding in the neuromuscular system of obese-diabetic mice.

Immunoreactivity for two derivatives of pro-opiomelanocortin, beta-endorphin and alpha-melanocortin (or corticotropin), was demonstrated, using a conventional immunoperoxidase method, in some of the intramuscular nerves in muscle sections from obese diabetic (ob/ob) mice and homozygous lean (+/+) mice. The endplate regions were visualized in the sections by staining for acetylcholinesterase reaction product. The proportion of muscle endplates with beta-endorphin-immunoreactive motor nerves was approximately 2.5-fold higher in soleus and extensor digitorum longus muscles and approximately 1.5-fold higher in the diaphragm of the obese (ob/ob) mice compared to the normal lean mice. The proportion of muscle endplates with alpha-melanotropin-immunoreactive motor nerves was between 30 and 53% lower, depending on the muscle type, in the ob/ob mice compared to the lean mice. The muscles of ob/ob and lean mice were investigated for the presence of specific binding sites for [125I]beta-endorphin and for [125I]corticotropin, using autoradiography. Some muscle fibres in soleus, extensor digitorum longus and diaphragm in both the ob/ob and the lean mice exhibited specific binding sites for the radioactive ligands. The binding sites were distributed over the entire surface in these muscle fibres. In the ob/ob mice the number of muscle fibres with specific [125I]beta-endorphin binding sites was six-fold higher in soleus and approximately 10-fold higher in extensor digitorum longus and diaphragm, than in the corresponding muscles of the lean mice. In contrast, the number of muscle fibres with specific [125I]corticotropin binding sites was similar in obese (ob/ob) and lean mice.(ABSTRACT TRUNCATED AT 250 WORDS)     

新生小鼠脑内移植荧光标记的孤雌胚胎干细胞的研究

目的通过将孤雌胚胎干细胞(parthenogenetic embryonic stem cells,PgESCs)移植到新生鼠脑内,观察其增殖及向神经细胞方向分化的形态特点。方法分别向出生24h及72h小鼠脑内注射增强型绿色荧光蛋白(enhanced green fluorescence protein,EGFP)标记的孤雌胚胎干细胞,并于移植3d和7d后进行取材、观察。结果与对照组相比,出生24h和72h后进行干细胞移植的新生鼠中,移植3d后,孤雌胚胎干细胞可以稳定的在小鼠脑内生长,形态和分布无明显变化;7d后能够分化为具有神经细胞样突起的细胞团。结论 PgESCs具有胚胎干细胞相似的体内分化潜能,为中枢神经系统疾病的细胞替代治疗奠定理论基础。     

Age-related deficits in brain androgen binding and metabolism, testosterone, and sexual behavior of male rats

Brain androgen binding and metabolism, serum testosterone (T), and sexual behavior were measured in old and young male Fischer 344 rats. After completion of sexual behavior tests, blood was collected for T assay and brains were removed for simultaneous measurements of cytosolic (ARc) and nuclear (ARn) androgen receptors and aromatase activity (AA) in the preoptic area (POA), hypothalamus (HYP) and amygdala (AMG). In Experiment 1, old and young intact males were examined. None of the old males ejaculated in any of the tests of sexual behavior whereas all of the young males ejaculated. The old males had lower levels of serum T, lower levels of ARn in the POA and HYP and lower levels of AA in the POA. The ARc levels of the old and young males did not differ. Experiment 2 was designed to determine if the deficits in brain androgen binding and metabolism were due to low levels of T. Old and young T-treated gonadectomized (GX-T) males and young intact (I) males were examined. T levels were comparable in the young and old GX-T males and were higher in each of these groups than in the young I males. In sexual behavior tests, all of the young but only 25% of the old GX-T males ejaculated. Although ARn levels in the old GX-T males were lower than in the young GX-T males, they were comparable to the young I male levels. No age-related differences in T induction of AA were observed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Autoradiographic distribution of non-dopaminergic binding sites labeled by [3H]haloperidol in rat brain

The regional distribution of binding sites labeled by [3H]haloperidol, in the presence of excess spiroperidol, was compared to the regional distribution of receptors labeled by [3H]SCH 23390 and [3H]sulpiride, [3H]SCH 23390 and [3H]sulpiride labeled distinct nuclei, such as the olfactory tubercle, caudate, globus pallidus, substantia nigra, and inferior and superior colliculi. In contrast, the distribution of binding sites labeled by [3H]haloperidol, in the presence of excess spiroperidol, were much more extensive. Some areas containing the highest density of sites labeled by [3H]haloperidol were the external plexiform layer of the olfactory bulb, the cerebral cortex, the paraventricular nuclei, the interpeduncular nucleus and the superior colliculus. The distribution of non-dopaminergic binding sites labeled by haloperidol was clearly quite different from that labeled by dopaminergic ligands.     

Characterization of specific binding sites for high-density lipoproteins on rat hepatocytes: Effects of estradiol and testosterone

Two types of binding sites for high-density lipoproteins (HDL): P₁ and P₂ K_dl=20 and K_d2=2.5μg/ml, N₁=130 and N₂=35 ng/mg cell protein) are identified on the surface of rat hepatocytes. Conditions for predominant determination of P₂ are created by employing radiolabeled lipoproteins (¹²⁵I-HDL) with a high specific activity (1000 dpm) and the differences in the kinetics of the P₁-and P₂-¹²⁵I-HDL complex formation. P₂ predominate on hepatocytes from females. The addition of estradiol to a culture of hepatocytes from males increases the content of P₂, while the addition of testosterone to hepatocytes from females decreases the content of P₂ to the levels determined in males. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 12, pp. 629–634, December, 1996     

Receptor autoradiographic evidence of specific brain natriuretic peptide binding sites in the porcine subfornical organ

Specific binding sites of brain natriuretic peptide (BNP), a newly discovered peptide in the subfornical organ (SFO) of porcine brain were investigated, following incubation of related tissue sections with 125I-BNP, then using autoradiography and an image analysis coupled with computer-assisted microdensitometry. Specific 125I-BNP binding sites were found to be localized in the SFO, an area densely labeled by 125I-alpha-rat atrial natriuretic peptide and 125I-(Sar1,Ile8)-angiotensin II. Specific 125I-BNP binding to the SFO was displaced by unlabeled BNP, with a high affinity, and was calculated to be Ka = 0.385 x 10(-9) M and Bmax = 40.1 fmol/mg using a LIGAND computer program. Acquisition of these present findings enhances our knowledge of the physiology of BNP, atrial natriuretic peptides and angiotensin II system in the SFO.     

Host-parasite relationships between Echinostoma caproni and RAG-2-deficient mice

The RAG-2-deficient mouse, a strain of genetically altered mice lacking B- and T-lymphocytes, was used as a host for Echinostoma caproni. In all, 12 male RAG mice were exposed to 25 cysts each, and 12 served as uninfected controls. Mice were necropsied at 2 and 3 weeks postinfection (p.i.). The mean number  ±SE (9.7 ± 2.4) of worms recovered from infected mice at 2 weeks p.i. was not significantly different from that recovered at 3 weeks p.i. (6.5 ± 2.2). The intestinal circumference of infected RAG mice was significantly greater than that of the controls at 2 and 3 weeks p.i. A significant goblet cell hyperplasia occurred at 2 weeks p.i., but the response was not effective in eliminating worms from the RAG mice. The effect of a high cyst burden was examined by exposure of 8 RAG and 8 ICR mice to 100 cysts each. The body length and area and the oral sucker area of worms grown in RAG mice were significantly greater than those of worms grown in ICR mice. Worm recovery at up to 3 months p.i. was examined in RAG mice exposed to 25 cysts and necropsied every 2 weeks p.i. The mean worm recovery recorded at 2 weeks p.i. was significantly greater than that noted at 12 weeks p.i., at which time worm rejection from the RAG mouse host first occurred. The RAG mouse is a useful host for studies on E. caproni in a murine host that lacks B- and T-lymphocytes. Received: 7 August 1998 / Accepted: 1 October 1998     

Gangliosides modulate glutamate receptor binding in rat brain synaptic plasma membranes

The influence of gangliosides on the binding of L-[3H]glutamate (Glu) to its receptor(s) on isolated rat brain synaptic plasma membranes was investigated in two different buffer systems using an in vitro filter binding assay. It was found that the tested pure monosialogangliosides GM1 and GM2 as well as the polysialogangliosides GT1b and GD1a enhanced binding by up to about 100%, but only in the presence of 5 mM calcium. The binding site involved was sensitive to quisqualate but insensitive to N-methyl-D-aspartate and kainate. GM1 did exert its stimulating effect by increasing the number of binding sites on the membranes whereas the receptor's affinity for L-Glu was unchanged. Regional differences in rat brain were found: while the hippocampus and cortex exhibited significant Ca/GM1-induced stimulation of Glu binding, the cerebellum was unaffected. Our results suggest modulation of at least one subtype of the Glu receptor by gangliosides.     

暴发性肝损伤肝性脑病大鼠血浆及脑游离氨基酸变化的相关分析

本文测定了D-氨基半乳糖所致暴发性肝损伤肝性脑病大鼠血浆及脑勺浆游离氨基酸含量的变化,并作相应的相关分析。结果表明,正常大鼠血浆及脑内各种氨基酸含量间均无相关。肝性脑病大鼠血浆及脑勺浆多种氨基酸水平均有增高,脑内大多数氨基酸含量与血浆相应氨基酸的变化无相关关系,但一些与肝性脑病发生相关的氨基酸水平与其相应的血浆含量呈显著相关。提示肝性脑病的发生与血脑屏障氨基酸转运功能选择性改变有关。     

Correlation between brain tryptophan hydroxylase activity and catalepsy in mice

Laboratory of Phenogenetics of Behavior, Institute of Cytology and Genetics, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. (Presented by Academician of the Academy of Medical Sciences of the USSR V. A. Matyukhin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 108, No. 9, pp. 269–271, September, 1989.     

Development of specific connectivity between premotor neurons and motoneurons in the brain stem and spinal cord

Astounding progress has been made during the past decade in understanding the general principles governing the development of the nervous system. An area of prime physiological interest that is being elucidated is how the neural circuitry that governs movement is established. The concerted application of molecular biological, anatomical, and electrophysiological techniques to this problem is yielding gratifying insight into how motoneuron, interneuron, and sensory neuron identities are determined, how these different neuron types establish specific axonal projections, and how they recognize and synapse upon each other in patterns that enable the nervous system to exercise precise control over skeletal musculature. This review is an attempt to convey to the physiologist some of the exciting discoveries that have been made, within a context that is intended to link molecular mechanism to behavioral realization. The focus is restricted to the development of monosynaptic connections onto skeletal motoneurons. Principal topics include the inductive mechanisms that pattern the placement and differentiation of motoneurons, Ia sensory afferents, and premotor interneurons; the molecular guidance mechanisms that pattern the projection of premotor axons in the brain stem and spinal cord; and the precision with which initial synaptic connections onto motoneurons are established, with emphasis on the relative roles played by cellular recognition versus electrical activity. It is hoped that this review will provide a guide to understanding both the existing literature and the advances that await this rapidly developing topic.     

Parsing relationships between dimensions of anxiety and action monitoring brain potentials in female undergraduates

Anxiety is associated with enhanced action monitoring. Research to date, however, has employed extreme group designs that fail to address the full spectrum of anxiety, and in which overlapping and co-occurring symptoms obscure the exact nature of the relationships between anxiety and action monitoring. To address these limitations, relationships between distinct dimensions of anxiety and neural indicators of action monitoring were examined in a sample of female undergraduates. Results revealed that higher anxious apprehension (i.e., worry) was associated with enhanced early action monitoring activity, as indexed by the error-related negativity/correct-response negativity. Anxious arousal (i.e., somatic tension) on the other hand, was unrelated to measures of action monitoring. These findings suggest that the anxiety-action monitoring link holds along the continuum of severity and is specific to the worry component of anxiety.