Androgen receptor systems in the brain stem of the primate

The nuclear uptake and retention of [³H]dihydrotestosterone ([³H]DHT) or one of its metabolites was studied in the cerebellum and brain stem of the rhesus monkey. Three days before the injection of the tritiated hormone, we removed both ovaries and the right adrenal gland of 3 female rhesus monkeys under ketamine and halothane or fluothane anesthesia with aseptic surgical procedures. Two days later, we removed the left adrenal gland under similar conditions. Shortly after the second operation, each animal received 100 mg prednisolone sodium succinate. On the day of autopsy, we injected into a femoral vein of each animal 1 μg of 5α-dihydro[1,2,4,5,6,7-³H]- testosterone (107 Ci/mmol). One of these animals also received an i.v. injection of 100 μg/kg body weight of unlabeled DHT to serve as a control. One hour after injection, we rapidly exsanguinated each animal through a femoral venous catheter and perfused the vascular system with approximately 3 1 of Ringer's solution through a femoral arterial catheter. The cerebella and brain stems were removed and processed for autoradiography. Unlike in the rat, nuclear uptake and retention of [³H]DHT was found in both motor and sensory systems of these monkeys and in other areas less well defined. These data indicate that there are major species differences in the nuclear uptake and retention of androgen by the cerebellum and brain stem of rats and primates.     

Topographic distribution of progestin target cells in hamster brain and pituitary after injection of [3H]R5020

The topographic distribution of progestin concentrating cells in the female hamster brain and pituitary was studied by thaw-mount autoradiography. Fifteen minutes after injection of [3H]R5020, a synthetic progestin, nuclear uptake and concentration of radioactivity was found in certain cells of the forebrain and midbrain, as well as in the anterior pituitary. Competition studies with unlabeled R5020 abolished and with progesterone reduced the nuclear uptake of radioactivity. In the forebrain, radioactively labeled cells are observed in n. septi lateralis, n. interstitialis striae terminalis, n. preopticus medialis and lateralis, n. periventricularis hypothalami, organum subfornicale, n. arcuatus hypothalami, n. ventromedialis hypothalami, n. dorsomedialis hypothalami and n. premammillaris ventralis. In the midbrain a few labeled cells are found in the griseum centrale. In the anterior pituitary, labeled cells are identified by immunostaining as luteinizing hormone-producing cells. The results of the autoradiographic study demonstrate nuclear progestin binding sites and suggest genomic action of progestin on the labeled structures, probably related to the modulation of gonadotropin secretion and sexual behavior in the brain and pituitary.     

Androgen and estrogen receptors in adult hamster brain

Both androgen and estrogen receptors are present in the hypothalamus-preoptic area and remaining ‘brain’ regions of gonadectomized adult male and female hamsters. No quantitative or qualitative sex differences are detectable in either receptor system. According to all biochemical criteria tested, both receptors are qualitatively similar to those present in mouse and rat brain. However, there are striking species differences in both the relative concentration and distribution of both androgen and estrogen receptors in hamster brain compared to mouse and rat brain.     

Circadian rhythm of nociception in the golden hamster

The response latency of golden hamsters to nociceptive stimuli was measured under cyclic lighting conditions and during constant illumination. A day-night rhythm of nociception was demonstrated; response latencies were significantly longer during the day. A circadian rhythm of nociception was displayed by hamsters maintained for 30 days in constant dim light. Short response latencies noted under these conditions were associated with the inactive period of the animals circadian cycle (subjective day). The experiments provide data which indicate the phase relationship between the circadian rhythms of nociception and locomotor activity differs under entrained and free-running conditions.     

Midbrain distribution of neurons with strong, sustained responses to lordosis trigger stimuli in the female golden hamster

Midbrain single units in anesthetized female hamsters were examined for pronounced, sustained responses to types of somatic stimuli which control the display of lordosis during periods of sexual receptivity. Units showing strong responses to lordosis trigger stimuli were widely distributed, but tended to be most concentrated in the deep superior colliculus, ventromedial midbrain and central gray, brain regions previously implicated, by other methods, in the control of hamster lordosis.     

Postnatal development of nicotinamide adenine dinucleotide phosphate-diaphorase-positive neurons in the retina of the golden hamster

The histochemical method was used to investigate the postnatal development of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) -positive neurons in retinas of the golden hamster. NADPH-d-positive neurons were discernible in the retina at postnatal day (P)1. From P4 onward to adulthood, when the retina acquired its laminated characteristics, NADPH-d- positive neurons were observed in the inner nuclear layer (INL) and the ganglion cell layer (GCL). Results showed that NADPH-d-positive neurons in INL and GCL followed different time courses and patterns in their development. NADPH-d-positive neurons in INL underwent a sharp increase from P4 to P8 (3.6-fold), followed by a decrease to 46% of the maximum at P12. This value was maintained relatively constant to the adult level. The mean diameters of NADPH-d-positive neurons in INL, which were smaller than those in the GCL for all ages, increased from P8 to P12 and from P20 to adulthood. As for neurons in the GCL, the increase in cell number was not so apparent for the earlier postnatal days until P20; thereafter, an obvious increase to the adult level was observed. The mean diameters of the NADPH-d-positive cell bodies in the GCL increased with age, except for P16-P20, during which time there was a slight and insignificant decrease. The tendency of changes in cell density was basically similar to that of the total number for both the INL and the GCL. Between P12 and P20, the density distribution map of the NADPH-d-positive neurons underwent dramatic changes: The highest density shifted from the upper central retina at the earlier postnatal days to the lower central retina in the adult. The two waves of increase in NADPH-d-positive neurons coincide with the process of axonal elongation and synaptogenesis and the acquisition of visual function and experience. It is suggested that these NADPH-d-positive neurons are related to these two developmental events.     

Nuclear uptake and retention of 3H-dihydrotestosterone or one of its metabolites in the lower brainstem of the baboon

The nuclear uptake and retention of androgen in the lower brainstem of the baboon was examined after the injection of 3H-5 alpha-dihydrotestosterone. A specific topographical pattern of localization was observed in both motor systems and somatosensory systems. The pattern was similar to that reported in the rhesus monkey. The localization found in the primate differs from that of the rat in that the localization demonstrated in the rat is primarily restricted to motor systems.     

Aromatization of androgen to estrogen by cultured turtle brain cells

Cells obtained from turtle forebrain can be maintained in culture for at least 3 weeks. The cells are capable of aromatizing [³H]androstenedione and [³H]testosterone to estrone and estradiol and several C-19 metabolites. There are marked differences in the quality and quantity of the products formed from the two substrates. Conditions in living cells favor accumulation of 17-hydroxylated steroids. Aromatase activity as measured by estrogen yield increases with time in culture. Estrogen content of 14-day-old cultures may be enhanced or reduced by addition of natural or synthetic steroids. This system may provide a model for studying the regulation of brain aromatization, an essential step in the expression of androgen action on certain behavioral and neuroendocrine responses.     

Both neural and global androgen receptor overexpression affect sexual dimorphism in the mouse brain

Testosterone is the main endocrine mechanism mediating sexual differentiation of the mammalian brain, although testosterone signalling is complex and important mechanistic questions remain. Notably, the extent to which testosterone acts via androgen receptors (AR) in this process remains unknown and it is also not clear where testosterone acts in the body to produce sexual dimorphisms in neuroanatomy. To address these questions, we used a transgenic mouse model of Cre/loxP‐driven AR overexpression in which AR was induced selectively in neural tissue (Nestin‐cre) or in all tissues (CMV‐cre). We then studied sexually dimorphic features of several well‐characterised sexual dimorphisms: calbindin‐immunoreactive neurones in the medial preoptic area (CALB‐SDN), tyrosine hydroxylase neurones in the anteroventral periventricular nucleus, and vasopressin‐immunoreactive neurones originating in the bed nucleus of the stria terminalis and their projections in the lateral septum. We additionally evaluated oestrogen receptor α immunoreactivity in these nuclei. Briefly, we found that global but not neural overexpression of AR resulted in masculinisation of CALB‐SDN nucleus volume, cell number and cell size in transgenic females. Furthermore, neural AR overexpression resulted in increased oestrogen receptor α staining in females compared to males in the medial preoptic area. AR overexpression did not affect other measures. Overall, the results of the present study provide support for the hypothesis that androgenic mechanisms external to the nervous system can affect sexual differentiation of the brain.     

Uptake of L-threo-dihydroxyphenylserine into human brain synaptosomes

Summary Out of four diastereoisomers of 3,4-dihydroxyphenylserine (DOPS), L-threo- and L-erythro-isomer were found to be taken up into human brain synaptosomes. The uptake of L-threo-DOPS was dependent on the temperature and sensitive to the metabolic inhibitors. The L-threo-DOPS uptake proved to be saturable and carrier-mediated transport with two different kinetic characteristics; a high-affinity and low-capacity and a low-affinity and high-capacity system. The apparent K_m values of these two systems were obtained to be 28.6M and 2.47 mM, respectively. The high-affinity transport was inhibited by glycine, L-tyrosine, L-proline, L-serine, L-Dopa, L-tryptophan, and L-phenylalanine. The inhibition by L-tyrosine was competitive in regard to L-threo-DOPS. The L-threo-DOPS uptake was inhibited by 2,4-dinitrophenol, sodium cyanide and other uncouplers of oxidative phosphorylation and by ouabain, an inhibitor of Na⁺, K⁺-ATPase, indicating that the uptake is coupled to ATP hydrolysis. On the other hand, L-threo-DOPS uptake by the low-affinity systerm was not inhibited by metabolic inhibitors, indicating that it may be facilitated diffusion common to high concentrations of L-amino acids.     

An autoradiographic study of the localization of androgen concentrating cells in the chaffinch

The distribution of labeled cells in the chaffinch brain has been examined by autoradiography after an intramuscular injection of [³H]testosterone. In the telencephalon labeled cells were particularly concentrated in nucleus magnocellularis neostriatalis anterioris, nucleus septalis lateralis, and hyperstriatum ventrale, pars caudale. In the diencephalon the nucleus periventricularis magnocellularis, the nucleus magnocellularis posterioris and the area infundibularis contained many heavily labeled cells. In the mesencephalon and medulla, labeled cells were found in the nucleus intercollicularis and in the nucleus nervi hypoglossi, respectively. Measurements of the density of grains per cell revealed (1) clear quantitative differences in the extent of labeling in different regions of the brain and (2) a wide variation in the density of labeling of individual cells within a region.The relationship between these sites of hormone binding and known sites of androgen action in the avian brain is discussed.     

Tyrosine hydroxylase neurons in the male hamster chemosensory pathway contain androgen receptors and are influenced by gonadal hormones

Chemosensory and hormonal signals, both of which are essential for mating in the male Syrian hamster, are relayed through a distinct forebrain circuit. Immunocytochemistry for tyrosine hydroxylase, a catecholamine biosynthetic enzyme, previously revealed immunoreactive neurons in the anterior and posterior medial amygdaloid nucleus, one of the nuclei within this pathway. In addition, dopamine-immunoreactive neurons were located in the posterior, but not hte anterior, medial amygdala. In the present study, tyrosine hydroxylase-immunostained neurons were also observed in other areas of the chemosensory pathway, including the posteromedial bed nucleus of the stria terminalis and the posterior, lateral part of the medial preoptic area, while dopamine immunostaining was only seen in the posteromedial bed nucleus of the stria terminalis. The colocalization of tyrosine hydroxylase and androgen receptors was examined in these four tyrosine hydroxylase cell groups by a double immunoperoxidase technique. The percentage of tyrosine hydroxylase-immunolabeled neurons that were also androgen receptor-immunoreactive was highest in the posterior medial amygdaloid nucleus (74%) and the bed nucleus of the stria terminalis (79%). Fewer tyrosine hydroxylase-immunostained neurons in the anterior medial amygdala (33%) and the medial preoptic area (4%) contained androgen receptors. Surprisingly, castration resulted in a significant decrease in the number of tyrosine hydroxylase-immunoreactive neurons only in the anterior medial amygdaloid nucleus, and this effect was transient. Six weeks after castratio, the anterior medial amygdala contained 61% fewer tyrosine hydroxylase-immunolabeled neurons, but 12 weeks after gonadectomy, immunostaining returned to intact values. The number of immunostained neurons in testosterone-replaced, castrated hamsters was not significantly different from that of intact or castrated animals at any time. The results of this study indicate that a substantial number of tyrosine hydroxylase-immunostained neurons in the chemosensory pathway are influenced by androgens; the majority of these neurons in the posterior medial amygdala and the posteromedial bed nucleus of the stria terminalis produce androgen receptors, and tyrosine hydroxylase immunoreactivity is altered by castration in the anterior medial amygdala. © 1993 Wiley-Liss, Inc.     

视觉保持测验对无症状性脑梗死患者认知损害的测定

目的　评估视觉保持测验 (VRT)在无症状性脑梗死 (SBI)中的应用价值。方法　比较 4 7例SBI和 31例正常人在VRT、韦氏成人智力量表 (WAIS RC)和简易智力状态量表 (MMSE)中的差异 ,并以WAIS RC为效标 ,评价VRT的效度。结果　SBI组的VRT得分以及WAIS RC总智商 (FIQ)、知觉组织因子 (POSs)和记忆 /注意因子 (MFSs)标准分显著低于正常组 (P =0 0 0 0～ 0 0 0 2 ) ,两组MMSE分数无显著性差异 (P =0 397)。VRT得分与WAIS RC三种智商的相关系数为 0 6 79～ 0 85 8。结论　VRT检测SBI的认知损害具有较好的临床效度 ,临床简单易行 ,可作为SBI认知损害的筛选测验。     

Expression of isotocin is male‐specifically up‐regulated by gonadal androgen in the medaka brain

Oxytocin, a mammalian neuropeptide primarily synthesised in the supraoptic and paraventricular nuclei of the hypothalamus, mediates a variety of physiological and behavioural processes, ranging from parturition and lactation to affiliation and prosociality. Multiple studies in rodents have shown that the expression of the oxytocin gene (Oxt) is stimulated by oestrogen, whereas androgen has no apparent effect. However, this finding is not consistent across all studies, and no study has examined sex steroid regulation of Oxt or its orthologues in other animals. In the present study, we show that, in the teleost fish, medaka (Oryzias latipes), the expression of the isotocin gene (it), the teleost orthologue of Oxt, in the parvocellular preoptic nuclei (homologous to the mammalian supraoptic nucleus) is male‐specifically up‐regulated by gonadal androgen, whereas it expression in the magnocellular/gigantocellular preoptic nuclei (homologous to the mammalian paraventricular nucleus) is independent of sex steroids in both sexes. None of the it‐expressing neurones appear to co‐express androgen receptors, suggesting that the effect of androgen on it expression is indirect. We found that the expression of a kisspeptin gene, kiss2, in the male brain is dependent on gonadal androgen, raising the possibility that the androgen‐dependent expression of it may be mediated by kiss2 neurones. Our data also show that the isotocin peptide synthesised in response to androgen is axonally transported to the posterior pituitary to act peripherally. Given that levels of it expression are higher in females than in males, androgen may serve to compensate for the female‐biased it expression to ensure a role for isotocin that is equally important for both sexes. These results are unexpectedly quite different from those reported in rodents, indicating that the regulatory role of sex steroids in Oxt/it expression has diverged during evolution, possibly with accompanying changes in the role of oxytocin/isotocin.     

(3H) glycine-accumulating neurons of the human retina

Isolated human retinas were incubated in physiological saline containing micromolar (3H) glycine. The types, distributions, and synaptologies of glycine-accumulating neurons were determined by light and electron microscope autoradiography. Two types of amacrine cells were discriminated on the bases of number of processes descending into the inner plexiform layer, density of label in light-microscope autoradiographs, size, and synaptic features: (1) Gly1 amacrine cells have moderate labeling, several oblique dendrites arising from the soma, and electron lucent synaptic terminals containing large presynaptic specializations, nd (2) Gly2 amacrine cells have dense labeling, a single proximal dendrite, and moderately electron-dense terminals with small presynaptic specializations. Gly1 amacrine cells constitute approximately 15% and Gly2 amacrine cells approximately 38% of all cells in the amacrine cell layer. The laminar distribution of label in the inner plexiform layer was measured by scanning microdensitometry, which provided a format for categorizing types of synaptic contacts. Many features of glycine-accumulating amacrine cell contacts were similar to those of cat AII/Gly2 amacrine cells: a diffuse yet bisublaminar distribution of label, concentration of synaptic output in sublamina a, rod bipolar cell input in sublamina b and gap junctions in mid-inner plexiform layer involving labeled cells. The evidence seems to indicate that human Gly2 amacrine cells and cat AII/Gly2 amacrine cells are homologous cell types. finally, some cone bipolar cells were labeled.     

In vitro measurement of cytosol and cell nuclear androgen receptors in male rat brain and pituitary

An in vitro assay procedure is described for measuring androgen receptor binding in cytosol and cell nuclei of brain and pituitary tissue using [³H]R1881 as ligand. The cell nuclear assay uses the exchange method, which permits assessment of endogenous occupancy of androgen receptors in brain and pituitary. Competition and saturation analysis indicated that [³H]R1881 binding has the specificity and nanomolar affinity expected of an androgen receptor.Moreover, we demonstrated that androgen receptor binding predominated in cytosol from castrated rats and in cell nuclei of male rats treated in vivo with testosterone. Furthermore, as expected, testicular feminized male rats showed low levels of putative androgen receptors in both cytosol and cell nuclei.     

Properties of superior colliculus neurons in the golden hamster

A laminar representation of sensory modalities was present in the hamster superior colliculus (SC) with upper laminar cells being exclusively visual, while intermediate and deeper layer cells were visual, somatic acoustic or multimodal. Receptive field (RF) properties of visual SC cells were studied quantitatively with stationary spots and moving bars of light of various sizes, velocities and directions of movement. The most effective stimuli were usually less than half of the diameter of the RF. Increasing stimulus size beyond a critical range produced progressively lower discharge rates even though the stimulus was confined within the borders of the RF. Low velocities (10–50°/sec) were most frequently optimal for both upper and lower laminar cells and the majority of cells were directionally selective. Movements in the upper nasal direction usually elicited the highest discharge rates and were thus preferred most frequently. However, directional preferences often could be minimized, or obliterated, by employing nonoptimal stimulus sizes and/or velocities. Most intermediate and deeper laminar somatic cells could be activated by gentle cutaneous stimuli and a general somatotopic plan, which was in register with the overlying visuotopy, was noted. Cells optimally, or solely, activated by noxious stimuli were also located, but RFs of such cells were extensive and a somatotopic plan was not apparent. Although species differences are apparent, the similarities between the organization and the RF properties of SC cells of the hamster and distantly related species are striking. Apparently the same SC system is adaptive in diverse species despite the very different behavioral repertories of these animals and their different ecological niches.     

Photoperiod and androgens act independently to induce spinal nucleus of the bulbocavernosus neuromuscular plasticity in the Siberian hamster,Phodopus sungorus

In the Siberian hamster, Phodopus sungorus, short-day photoperiods induce the winter phenotype, which in males includes a decrease in the production of androgens and changes in physiology to inhibit reproduction. Motoneurones of the spinal nucleus of the bulbocavernosus (SNB) and their target muscles, the bulbocavernosus and the levator ani, a neuromuscular system involved in male copulation, also display seasonal plasticity in P. sungorus. It is not known whether the plasticity seen in the SNB system of gonadally intact hamsters is due to the effects of photoperiod per se, or to the photoperiod-induced changes in androgen production. To answer this question, we castrated adult male hamsters from long days and then implanted them with capsules containing either testosterone or blanks. Half of the hamsters from each hormone condition were moved into short photoperiod (8 : 16 h light/dark cycle) while the rest were maintained under long-day conditions (15 : 9 h light/dark cycle). After 15 weeks, many measures of the SNB system, such as somata size and weight of target muscles, responded only to androgen, not to photoperiod. However, there were effects of photoperiod on the neuromuscular junctions (NMJs) that were independent of androgen status. For example, the number of synaptic zones per NMJ and the area of the NMJs were significantly increased by short days and/or testosterone treatment. The two factors exerted an additive, rather than an interactive, effect on these measures. Another striated muscle, the extensor digitorum longus, which is present in both sexes and plays no specialized role in reproduction, displayed neither an effect of androgen nor of photoperiod on fibre size or NMJ structure. These results suggest that, in addition to androgenic effects on SNB plasticity, there is also an androgen-independent effect of photoperiod on the SNB neuromuscular system.