Techniques for the autoradiography of diffusible compounds

In situ metabolomic analysis of osteonecrosis of the femoral head (ONFH) using MALDI MSI

Osteonecrosis of the femoral head (ONFH) is a common orthopedic disease characterized by disability and deformity. To better understand ONFH at molecular level and to explore the possibility of early diagnosis, instead of diagnosis based on macroscopic spatial characteristics, a matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) method was developed for ONFH disease for the first time. The most challenging step for ONFH MSI is to deal with human bone tissues which are much harder than the other biological samples studied by the reported MSI studies. In this work, the MSI sectioning method of hard bone tissues was established using tender acids and a series of test criteria. Small-molecule metabolites, such as lipids and amino acids, were detected in bone sections, realizing the in situ detection of spatial distribution of biometabolites. By comparing the distribution of metabolites from different regions of normal femoral head, ONFH bone tissue (ONBT), and adjacent ONFH bone tissue (ANBT), the whole process of femoral head from normal stage to necrosis was monitored and visualized at molecular level. Moreover, this developed MSI method was used for metabolomics study of ONFH. 72 differential metabolites were identified, suggesting that disturbances in energy metabolism and lipid metabolism affected the normal life activities of osteoblasts and osteoclasts. This study provides new perspectives for future pathological studies of ONFH.

Estrogen Receptors and Post-Receptor Markers in Human Breast Cancer: A Reappraisal

Several major defects in the estrogen receptor pathway have been evidenced in most human breast cancers by an immunofluorescence tracing of estradiol receptor complexes at the single cell level. Endogenous peroxidase seems a reliable postreceptor marker for estrogen-sensitive breast cancer cells. Since almost all human breast cancers appear to include both hormone-sensitive and autonomous cell populations, a combined use of endocrine and cytotoxic regimens is urged. The hormonal regulation of tumor growth parameters could be exploited in order to achieve a maximum recruitment of synchronized tumor cells at risk to chemotherapy.

Comparison between thaw-mounting and use of conductive tape for sample preparation in ToF-SIMS imaging of lipids in Drosophila microRNA-14 model

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging elucidates molecular distributions in tissue sections, providing useful information about the metabolic pathways linked to diseases. However, delocalization of the analytes and inadequate tissue adherence during sample preparation are among some of the unfortunate phenomena associated with this technique due to their role in the reduction of the quality, reliability, and spatial resolution of the ToF-SIMS images. For these reasons, ToF-SIMS imaging requires a more rigorous sample preparation method in order to preserve the natural state of the tissues. The traditional thaw-mounting method is particularly vulnerable to altered distributions of the analytes due to thermal effects, as well as to tissue shrinkage. In the present study, the authors made comparisons of different tissue mounting methods, including the thaw-mounting method. The authors used conductive tape as the tissue-mounting material on the substrate because it does not require heat from the finger for the tissue section to adhere to the substrate and can reduce charge accumulation during data acquisition. With the conductive-tape sampling method, they were able to acquire reproducible tissue sections and high-quality images without redistribution of the molecules. Also, the authors were successful in preserving the natural states and chemical distributions of the different components of fat metabolites such as diacylglycerol and fatty acids by using the tape-supported sampling in microRNA-14 (miR-14) deleted Drosophila models. The method highlighted here shows an improvement in the accuracy of mass spectrometric imaging of tissue samples.

Cellular changes following direct vitamin D injection into the uraemia-induced hyperplastic parathyroid gland

Background. Hyperplasia of the parathyroid gland (PTG) is associated not only with excessive secretion of parathyroid hormone (PTH) but also with changes in the parathyroid cell (PTC) characteristics (i.e. hyperproliferative activity and low contents of vitamin D and calcium-sensing receptors). The control of PTG hyperplasia is most important in the management of secondary hyperparathyroidism (SHPT), because the advanced stage of hyperplasia is considered irreversible. For the better control of the PTH level in dialysis patients with such advanced SHPT, percutaneous vitamin D injection therapy (PDIT) under ultrasonographic guidance was developed and various cellular changes caused by this treatment were also investigated using an animal model.

Methods. The PTGs of Sprague–Dawley rats, which had been 5/6-nephrectomized and fed a high-phosphate diet, were treated with the direct injections of vitamin D agents, and cellular effects focusing the above-mentioned characters were investigated.

Results. An adequacy of the direct injection technique into the rats’ PTGs and the successful effects of this treatment in various biochemical parameters were confirmed. Such characteristics of advanced SHPT were simultaneously improved; in particular, it was confirmed that this treatment may be effective in controlling PTG hyperplasia by, at least in part, apoptosis-induced cell death.

Conclusions. A locally high level of vitamin D strongly may suppress PTH secretion and regress hyperplasia, which is involved in the induction of apoptosis in PTCs, based on the simultaneous improvements of cellular characters of advanced SHPT. The PTH control introduced by this treatment successfully ameliorated osteitis fibrosa (high bone turnover rate).

Molecular and morphological approach of uremia-induced hyperplastic parathyroid gland following direct maxacalcitol injection

The mechanisms explaining the clinical effects of direct maxacalcitol (OCT) injection into the hyperplastic parathyroid gland (PTG) in uremic patients with advanced secondary hyperparathyroidism (SHPT) were investigated by molecular and morphological examination. PTG of uremia-induced SHPT model rats were treated by a direct injection of OCT (DI-OCT) or vehicle (DI-vehicle). The changes in serum intact parathyroid hormone (intact-PTH) level, vitamin D and Ca-sensing receptor (VDR and CaSR, respectively) expression levels in PTG, and the calcium (Ca)-PTH response curve were examined; the induction of apoptosis in parathyroid cells (PTC) was also analyzed by the TUNEL method, DNA electrophoresis, and electron microscopic examination. Serum intact-PTH level following DI-OCT significantly decreased. Upregulation of both VDR and CaSR, a clear shift to the left downward in the Ca-PTH curve, and many apoptotic PTCs were observed in the DI-OCT-treated PTGs. However, these findings were not observed in the DI-vehicle-treated PTGs. Moreover, these effects were confirmed by the DI-OCT into one PTG and DI-vehicle alone into another PTG in the same rat. DI-OCT may introduce simultaneous VDR and CaSR upregulation and the regression of hyperplastic PTG, and these effects may provide a strategy for strongly suppressing PTH level in uremia-induced advanced SHPT.

Penetration of ASM 981 in canine skin: a comparative study

ASM 981 has been developed for topical treatment of inflammatory skin diseases. It specifically inhibits the production and release of pro-inflammatory cytokines. We measured the skin penetration of ASM 981 in canine skin and compared penetration in living and frozen skin. To make penetration of ASM 981 visible in dog skin, tritium labelled ASM 981 was applied to a living dog and to defrosted skin of the same dog. Using qualitative autoradiography the radioactive molecules were detected in the lumen of the hair follicles until the infundibulum, around the superficial parts of the hair follicles and into a depth of the dermis of 200 to 500 microm. Activity could not be found in deeper parts of the hair follicles, the dermis or in the sebaceous glands. Penetration of ASM 981 is low in canine skin and is only equally spread in the upper third of the dermis 24 hours after application. Penetration in frozen skin takes even longer than in living canine skin but shows the same distribution.

Receptor microscopic autoradiography for the study of percutaneous absorption, in vivo skin penetration, and cellular-intercellular deposition

INTRODUCTION

Microscopic autoradiography with cellular resolution and preservation of in vivo conditions is potentially the method of choice to gain detailed information about sites of deposition and retention in the epidermis and of penetration to the dermis after topical application of drugs. We tested this using (3)H-Maxacalcitol.

METHODS

Dorsal skin of adult rats was treated in vivo with ointment containing 1 or 40 microg/kg body weight of the vitamin D analogue (3)H-Maxacalcitol for periods of 0.5, 2, 8, 24, 48, or 168 h. Samples of skin exposed to the ointment and control samples remote from the treatment site were excised and freeze-mounted, and 4-microm frozen sections were exposed to nuclear emulsion.

RESULTS

Two penetration routes to the dermis could be distinguished: one via epidermal cell layers and the other via hair follicles. Highest uptake and retention of radiolabeled steroid was observed in stratum corneum and in intercellular spaces of stratum granulosum. By contrast, cell boundaries and intercellular spaces in the stratum spinosum and basale contained low levels of radioactivity. Keratinocytes in these layers showed high concentration in the cytoplasm at early time intervals, when surrounding radioactivity levels were high, but high nuclear and low or no cytoplasmic concentration at late time intervals, when surrounding radioactivity levels were low.

DISCUSSION

The autoradiographic method provides detailed information on time- and dose-related distribution of radiolabeled compound at the cellular level that is not obtainable with common radioassays and biochemical procedures. A sustained concentration and retention of radiolabeled steroid in the stratum corneum and intercellular space of the stratum granulosum indicate a selective deposition in components of secreted-membrane-coating granules and suggest a temporary barrier and depot for slow release. The differential cytoplasmic-nuclear distribution in the stratum Malpighi suggests functional correlation to a toxic-hormetic reversal of action on cell proliferation, from high-dose inhibitory effects associated with high extranuclear concentration as utilized in the treatment of psoriasis, to low-dose stimulatory effects associated with high nuclear and low cytoplasmic concentration as applicable in wound healing.

Freeze-substitution: origins and applications

Freeze-substitution is a physicochemical process in which biological specimens are immobilized and stabilized for microscopy. Water frozen within cells is replaced by organic solvents at subzero temperatures. Freeze-substitution is widely used for ultrastructural and immunocytochemical analyses of cells by transmission and scanning electron microscopy. Less well recognized is its superiority over conventional chemical fixation in preserving labile and rare tissue antigens for immunocytochemistry by light microscopy. In the postgenome era, the focus of molecular genetics will shift from analyzing DNA sequence structure to elucidating the function of gene networks, the intercellular effects of polygenetic diseases, and the conformational rearrangements of proteins in situ. Novel strategies will be needed to integrate knowledge of chemical structures of normal and abnormal macromolecules with the physiology and developmental biology of cells and tissues from whole organisms. This review summarizes the progress and future prospects of freeze-substitution for such explorations.

In vivo dose-related receptor binding of the vitamin D analogue [3H]-1,25-dihydroxy-22-oxavitamin D3 (OCT) in rat parathyroid, kidney distal and proximal tubules, duodenum, and skin, studied by quantitative receptor autoradiography

1,25-Dihydroxy-22-oxavitamin D3 (OCT) is a new synthetic analogue of 1,25(OH)2D3 with a low calcemic effect. This study utilized quantitative receptor autoradiography to determine the dose-related receptor binding and saturation among the vitamin D target cells: parathyroid chief cells, kidney distal and proximal tubule epithelium, duodenal absorptive epithelium, and epidermal keratinocytes. Rats were injected with 0.25, 0.5, 1.0, 2.0, 4.0, 8.0, or 16.0 microgram/kg bw of [26-3H]-OCT and sacrificed 1 hr afterwards. Then autoradiographs were prepared under identical conditions. In these target cells, nuclear uptake of radioactivity increased with dose and then achieved a plateau. However, their saturation doses showed differences: parathyroid chief cells 1-2 microgram duodenal absorptive epithelium, distal tubule epithelium, and epidermal keratinocytes 4-6 microgram proximal tubule epithelium 8 microgram (per kg bw). In contrast, in nontarget cells, such as liver and duodenal smooth muscle, radioactivity did not concentrate in the nuclei but increased in the cytoplasm with dose, without plateauing. These results provide the first information on the relative saturabilities of various target cell populations with a vitamin D ligand. Parathyroid chief cells required the relatively lowest receptor saturation dose. This suggests a high sensitivity and response to OCT treatment with related therapeutic potential for the regulation of parathyroid function.

Receptor localization of steroid hormones and drugs: discoveries through the use of thaw-mount and dry-mount autoradiography

The history of receptor autoradiography, its development and applications, testify to the utility of this histochemical technique for localizing radiolabeled hormones and drugs at cellular and subcellular sites of action in intact tissues. Localization of diffusible compounds has been a challenge that was met through the introduction of the "thaw-mount" and "dry-mount" autoradiographic techniques thirty years ago. With this cellular receptor autoradiography, used alone or combined with other histochemical techniques, sites of specific binding and deposition in vivo and in vitro have been characterized. Numerous discoveries, some reviewed in this article, provided information that led to new concepts and opened new areas of research. As an example, in recent years more than fifty target tissues for vitamin D have been specified, challenging the conventional view about the main biological role of vitamin D. The functions of most of these vitamin D target tissues are unrelated to the regulation of systemic calcium homeostasis, but pertain to the (seasonal) regulation of endo- and exocrine secretion, cell proliferation, reproduction, neural, immune and cardiovascular responses, and adaptation to stress. Receptor autoradiography with cellular resolution has become an indispensable tool in drug research and development, since information can be obtained that is difficult or impossible to gain otherwise.

Nuclear receptors for 1,25-dihydroxy-22-oxavitamin D3 (OCT) and 1,25-dihydroxyvitamin D3 in gastric gland neck mucous cells and gastrin enteroendocrine cells

22-Oxacalcitriol the analog with low calcemic effect and the original hormone 1,25(OH)2 vitamin D3 were localized by autoradiography in mouse stomach at different time intervals after intravenous injection. Both compounds showed a distinct nuclear concentration and retention in neck mucous cells of gastric and pyloric glands, and in dispersed endocrine cells in the antrum region. When the nuclear binding of radioactively labelled compound was compared between gastric neck cells and duodenal absorptive cells, binding was low but sustained in neck cells. Peak uptake after the injection was between 8 and 12 h in neck cells, but between 15 min and 30 min in duodenal villous epithelium. In the duodenum, weak nuclear labelling appeared at 8 h and was undetectable at 12 h under the conditions of the experiment. Nuclear labelling of neck cells remained detectable at 12 h and even after 24 h, similarly for both OCT and 1,25(OH)2 vitamin D3. These results suggest that the stomach is an important target tissue for vitamin D and its analog OCT. Regulation of neck cell functions is suggested, such as proliferation and differentiation of surface epithelium and gastric gland epithelium, and neck cell secretion of acidic mucus. Regulation is also indicated of G-cell gastrin secretion associated with gastrin paracrine effects on parietal cell HCl and intrinsic factor secretion, chief cell pepsinogen secretion, neck cell proliferation, as well as endocrine effects on systemic calcium homeostasis.

Distribution of 1,25-dihydroxyvitamin D3[22-oxa] in vivo receptor binding in adult and developing skin

Because of the therapeutic potential of oxacalcitriol (OCT, 22-oxa-dihydroxyvitamin D3), in vivo studies were conducted in adult and neonatal rats to identify the nuclear receptor sites of action in different tissues of the skin. Results were compared with those for 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and oestradiol from previous studies. Autoradiograms were prepared from the dorsal skin of adult rats and the skin of the leg and head regions of neonatal rats 1 or 2 h after the injection of 3H-OCT. Specific nuclear concentrations of radioactivity, eliminated by competition with unlabelled OCT or 1,25(OH)2D3, were found in cells of the epidermis, outer hair sheath, hair bulb and sebaceous glands, but were absent or low in most fibroblasts of the dermis and hypodermis. The strongest nuclear binding of OCT was conspicuous in outer hair sheaths, where it was 1.5 to 3.2 times higher than in keratinocytes of the epidermis. The distribution of nuclear receptors for OCT was similar to that for 1,25(OH)2D3 but in part dissimilar to that for oestradiol. Oestradiol binding was found in the epidermis and hair sheaths, and also predominantly in fibroblasts of the dermis and hair dermal papillae. The results suggest genomic regulatory effects of OCT, similar to the effects of vitamin D, on proliferation, differentiation and activity of keratinocytes, growth and maintenance of hair, and proliferation and secretion of sebaceous glands. This may be utilized therapeutically, since OCT has a lower calcaemic effect than 1,25(OH)2D3.

1,25-Dihydroxyvitamin D3 and 22-oxa-1,25-dihydroxyvitamin D3 in vivo nuclear receptor binding in developing bone during endochondral and intramembranous ossification

Target cells for 3H-labeled 1 alpha, 25(OH)2 vitamin D3 [1,25(OH)2D3, vitamin D] and its analog 3H-labeled 22-oxa-1 alpha, 25(OH)2 vitamin D3 (OCT) have been identified during endochondral and intramembranous ossification in developing, undecalcified, unembedded bone, using thaw-mount autoradiography. Two-day-old neonatal rats were injected with [3H]1,25(OH)2D3 or [3H]OCT; after 2 h leg, spine, and head were frozen and sectioned. In the epiphyseal-metaphyseal region specific nuclear concentrations of [3H]1,25(OH)2D3 and [3H]OCT were observed in identical cell populations, being low in cells of the articular and resting zone, intermediate in the proliferating zone, and highest in hypertrophic chondrocytes and in osteoblasts and precursor cells. In the primary spongiosa intertrabecular spaces there were a large number of cells with nuclear labeling--probably osteoblasts and precursor cells. In contrast, in the secondary spongiosa intertrabecular spaces, apparent blood-forming cells were mostly unlabeled. Osteoblasts along bone spicules and compact bone in long bones, vertebrae, and head also showed strong nuclear labeling, as did cells of the periosteum. These data suggest that 1,25(OH)2D3 and OCT regulate development, differentiation, and activities of chondrocytes and osteoblasts, including differentiation of resting chondrocytes into proliferating and hypertrophic chondrocytes that involve "chondroclastic" enlargement of lacunae and "trans-differentiation" of surviving hypertrophic chondrocytes; differentiation of stroma cells into osteoblasts; and in periosteum and other regions of intramembranous ossification differentiation of precursor cells and osteoblasts. Nuclear receptor binding and their selective and hierarchical distribution during cell differentiation appear to correspond to multiple genomic effects toward growth, regeneration and repair. The findings indicate a physiological significance and therapeutic potential of 1,25(OH)2D3 and in particular of its less hypercalcemic analog OCT.

Vitamin D3 (soltriol) nuclear receptors in abdominal scent gland and skin of Siberian hamster (Phodopus sungorus) localized by autoradiography and immunohistochemistry

In vivo autoradiography with [3H]1,25-dihydroxycholecalciferol (vitamin D, soltriol) and immunostaining with antibodies to vitamin D receptor were applied to identify specific binding sites in the abdominal scent gland of male Siberian hamster (Phodopus sungorus). Nuclear concentration of radiolabeled hormone and receptor antibodies was observed in the corresponding cell types including basal cells of sebaceous glands, cells of the outer hair sheaths and hair bulbs, and also keratinocytes in the epidermis. Cells of the hair dermal papillae and fibroblasts of the dermis did not show nuclear labeling. There was good correspondence between the autoradiographic and immunohistochemical data. The results indicate the presence of receptors for vitamin D-soltriol and suggest a seasonal regulation of scent gland marking activities by this steroid hormone of sunlight in cooperation with the sex steroid testosterone.

Dexamethasone target sites in the central nervous system and their potential relevance to mental illness

1. The topical distribution of tritiated dexamethasone (DEX), a potent synthetic glucocorticoid of widespread use in the diagnosis and assessment of mental illness, was studied in rat CNS by autoradiography to obtain information on potential target sites for feedback and other centrally mediated effects of glucocorticoids. 2. The cells of the arcuate nucleus of the hypothalamus and the lateral thalamic nuclei displayed the most concentrated nuclear accumulation of silver grains. 3. Significant accumulation, exceeding that found in the hippocampal formation, also occurred in the cells of the ventromedial, periventricular, and paraventricular nuclei of the hypothalamus, the locus ceruleus, the nucleus tractus solitarii, and the area postrema, none of which are targeted by corticosterone, the native glucocorticoid of the rat. 4. Nuclear accumulation of silver grains was prominent in neural and glial cells of the cerebral cortex, the olfactory nucleus, the dorsolateral septum, the amygdala, the subfornical organ, the lateral parabrachial, medial trapezoid, and dorsal reticular nuclei, the nucleus centralis of the raphe, the cerebellum, and vascular tissues. 5. The localization of DEX in hypothalamic and brain-stem nuclei coincided with that of the glucocorticoid receptor, possibly implicating these sites in direct or modulating effects of glucocorticoids in various forms of mental disturbance, including depression, anxiety, panic disorders, and alcohol withdrawal. 6. The extent to which various CNS regions targeted by DEX feature in negative feedback control of adrenocortical secretion remains to be defined, as does the site of impaired feedback disclosed by the dexamethasone suppression test in psychiatric patients.

Nuclear receptor sites for vitamin D-soltriol in midbrain and hindbrain of Siberian hamster (Phodopus sungorus) assessed by autoradiography

Autoradiograms were prepared from midbrains and hindbrains of male and female Siberian hamsters (Phodopus sungorus), kept under short-day or long-day illumination, after injection of tritium-labeled 1,25-dihydroxycholecalciferol (vitamin D, soltriol). Concentration and retention of radioactivity was noted in nuclei of certain neurons, glial cells, and ependymal cells, and in choroid epithelium. Labeled neurons of varying intensity were found throughout the brainstem in distinct populations at characteristic topographical sites, which include cranial nerve motor nuclei, the nucleus (n.) reticularis tegmenti pontis, the caudoventral region of the n. raphe dorsalis, the n. trapezoides, the n. vestibularis lateralis and n. vestibularis superior, neurons in the various nuclei of the sensory trigeminus, accessory optic nuclei, scattered neurons in nuclei of the reticular formation, the n. ambiguus, certain cells in the area postrema, and many others. Glial cells with nuclear labeling, probably microglia, were scattered predominantly in or near myelinated nerve fascicles. The choroid epithelium showed strong nuclear labeling throughout the ventricle. Nuclear labeling of ependyma was variable and weak, mainly at ventral and lateral extensions (recesses) of the ventricle. The extensive presence of nuclear binding in select neural structures indicates that vitamin D exerts specific genomic effects on cell populations that are known to be involved in the regulation of motor, sensory, autonomic, neuroendocrine, metabolic, and immune functions. The results of these studies, in conjunction with those from other brain and peripheral tissues, recognize vitamin D-soltriol as a steroid hormone with a wide scope of hormone-specific target cells, similar to estrogen, androgen, and adrenal steroids, and which are topographically distinct and characteristic for its functions as the steroid hormone of sunlight.

Ecdysteroid binding sites in gastrolith forming tissue and stomach during the molting cycle of crayfish Procambarus clarkii

The distribution of ecdysteroid binding sites in the stomach and gastrolith disc tissue of crayfish (Procambarus clarkii) was examined in relation to the molting stage by thaw-mount autoradiography. The radiolabeled hormone analogue ponasterone A (25-deoxy-20-hydroxyecdysone) was used. Ecdysteroid binding sites were demonstrated only in certain molting stages, the small gastrolith period and the aftermolt stage. In gastrolith epithelium, ponasterone A binding sites first appeared in the cytoplasm, and then in the nuclei and cytoplasm. In the stomach epithelium, many nuclear binding sites were detectable during the period of gastrolith secretion. These periodical changes in specific ponasterone A binding when correlated with the molting stages clearly show that ecdysteroids may function as an initiator for gastrolith formation and reabsorption. The findings also suggest that ecdysteroids control calcium transport in the stomach epithelium. The time-related and functional differences of cytoplasmic and nuclear concentration of ecdysteroid receptors indicate the presence of cytoplasmic and nuclear receptors associated with specific actions.

Vitamin D receptors in heart: effects on atrial natriuretic factor

We report that receptors for vitamin D exist in distinct regions of the heart in female and male mice, predominantly in the right atrium where most of the cardial atrial natriuretic peptide (ANF) is produced. Tritiated 1,25-dihydroxyvitamin D3 (1,25-D3, vitamin D, soltriol) and ANF are colocalized in nuclei and cytoplasm respectively in identical cardiomyocytes. Changes of ANF tissue and blood levels under dietary deficiency and treatment with 1,25-D3 suggest direct genomic actions of vitamin D on myoendocrine cells of the atrium for the regulation of ANF manufacture and secretion. These results were obtained by combining thaw-mount autoradiography with immunocytochemistry using tritiated 1,25-D3 and an antibody against rat ANF. This antibody was also used in a radioimmunoassay to determine atrial natriuretic factor in plasma, atria and ventricles of normal or vitamin D-deficient mice.

Ecdysteroid receptors in the central nervous system of Manduca sexta: their changes in distribution and quantity during larval-pupal development

Ecdysteroids act initially by binding to nuclear and possibly also extranuclear receptors. The presence and expression of these receptors in the insect brain was investigated in the present study as a means of defining these neurons involved in ecdysteroid-regulated processes at different developmental stages. Early in the fifth larval stadium of Manduca sexta, when endogenous ecdysteroid levels are low, receptors for ecdysteroids in cerebral neurons are either absent or present at low levels. Receptors can be reliably detected only on day 0 and are not found again until day 3.5, at the beginning of the commitment peak in the ecdysteroid titer, when they occur in a small stage-specific population of cells. At this time, ecdysteroid receptors are found mainly in nuclei but are also observed at low levels in cytoplasm. By day 4.8, ecdysteroid receptors are exclusively nuclear, and the number of target cells has increased dramatically in several brain regions, including those with known neurosecretory cell groups. This population and organization of ecdysteroid target cells is constant up to day 6, after which time the number of target neurons declines. By day 7.8, only 10% of the number of labelled neurons seen on days 4.8-6.8 remain in peripheral areas. In the pupal brains, ecdysteroid receptors reappear in a new population of neurons. The results indicate changes in the genomic regulation of a varying neuron population by ecdysteroids during fifth stadium development.

Autoradiographic analysis of the in vivo distribution of 3H-imipramine and 3H-desipramine in brain: comparison to in vitro binding patterns

Using high resolution autoradiographic techniques, the distribution of radioactivity in forebrain and brainstem was assessed after IV injection of 3H-impramine or 3H-desipramine. Results were compared with regional binding of the drugs to brain sections in vitro. Similar topographic binding of 3H-imipramine and 3H-desipramine was observed in vitro among brain regions, except in the paraventricular nucleus of the hypothalamus and locus coeruleus, where binding was greater for 3H-desipramine. For both 3H-desipramine and 3H-imipramine, some brain regions that exhibited high binding in vitro also showed high accumulation after in vivo injection. However, certain regions that contained high densities of binding sites for the antidepressant drugs as measured by in vitro binding showed very low accumulation of radioactivity after in vivo treatment. Such regions included the dentate gyrus of the hippocampus, layer 1 of piriform cortex, caudate-putamen, pontine and midbrain central gray, and cerebellar granular layer. Compared to in vitro binding of the drugs, the distribution of imipramine and desipramine in vivo appears more anatomically selective. For imipramine, primary sites of action in vivo, as indicated by the topographic distribution in brain, appear to be the locus coeruleus, hippocampus, lateral septal nucleus, and amygdala. For desipramine, the greatest accumulation in vivo was found in the locus coeruleus, paraventricular nucleus of the hypothalamus, and anterior thalamic nuclei.

Ecdysteroid binding sites localized by autoradiography in the central nervous system of precommitment fifth-stadium Manduca sexta larvae

Brains and subesophageal ganglia from day 3.5 fifth stadium larvae of Manduca sexta were incubated in vitro with 4 nM tritiated ponasterone A, a 20-hydroxyecdysone analog, to determine whether uptake and specific binding of ecdysteroids occur at a cellular level. These tissues, which were taken just prior to the commitment peak in the hemolymph-ecdysteroid titer, showed saturable uptake of 3H-ponasterone A after 40-60 min of incubation. Uptake was blocked by the addition of 400 nM unlabelled ponasterone A, or of 500 nM or 1000 nM 20-hydroxyecdysone. RH 5849, a synthetic 20-hydroxyecdysone agonist with a long half-life, for which ecdysteroid receptors have low affinity, also reduced ponasterone A uptake at a concentration of 10 microM. Autoradiographs of 4 microns sections of brains revealed distinct nuclear concentrations of silver grains over cell populations in the pars intercerebralis, pars lateralis, and ventral tritocerebrum. Nuclear labelling was also found in many small cells around the mushroom bodies and the neuropil, and between the inner and outer larval optic lobes. Nuclear labelling of cells in the subesophageal ganglion was observed in the fronto-medial and lateral regions, in small cells around the neuropil, and caudally in a few large neurons. In addition to cells with nuclear labelling, both brains and ganglia at this development stage contained cells with exclusively cytoplasmic or both nuclear and cytoplasmic labelling. None of these apparent binding sites were observed in the competition experiments, suggesting that the binding is specific.

Estradiol distribution and penetration in rat skin after topical application, studied by high resolution autoradiography

Transdermal pathways and targets in the skin for estradiol were investigated using dry-mount autoradiography. 3H-estradiol-17 beta was applied at doses of 30.1 pmol, 120.4 pmol and 301 pmol/cm2 to shaved rat skin in the dorsal neck region. Vehicles were DMSO, ethylene glycol or sesame oil. After 2 h of topical treatment with 30.1 pmol 3H-estradiol x cm-2 dissolved in DMSO a distinct cellular distribution was apparent. Target cells with concentrations of radioactivity were found in epidermis, sebaceous glands, dermal papillae of hair and fibroblasts. After treatment with 120.4 and 301 pmol/cm2, a penetration gradient of radioactivity was recognizable however it masked specific cellular and subcellular uptake. The stratum corneum accumulated and retained radioactivity, apparently forming a depot for the hormone. Strong concentration and retention of the hormone was conspicuous in sebaceous glands for more than 24 h, suggesting that sebaceous glands serve as a second storage site for the hormone. In all autoradiograms two penetration pathways to the dermis were visible: one through the stratum corneum and epidermis, the other through the hair canals and hair sheaths.

Binding of radiolabeled estrogens by human cells in vitro: implications to the development of a new diagnostic and therapeutic modality in the treatment of malignancies with estrogen receptors

An in vitro technique was employed to demonstrate the binding of Auger electron-emitting nuclide-labeled estrogenic compounds by a variety of human cell types. Human granulosa cells, endometrium, and MCF-7 breast cancer cells were incubated with either 16 alpha-[I125]-iodoestradiol-17 beta or 16 alpha-[I123]-iodoestradiol-17 beta in vitro. Autoradiographic techniques were subsequently utilized and revealed that binding of these estrogenic compounds by all three types of cells did occur and that this binding was inhibited by excess unlabeled estradiol. Histologic examination was not able to demonstrate nuclear-specific binding in all instances, however. These compounds are potentially useful in both diagnostic and therapeutic settings and this study is the first to provide such data from human tissue.

1,25(OH)2 vitamin D3 sites of action in spinal cord and sensory ganglion

Autoradiographic studies revealed concentration of 3H 1,25(OH)2 vitamin D3 in nuclei of certain neurons in the spinal cord of adult and neonatal mice, fed a normal or a vitamin D deficient diet. Nuclear uptake and retention was strongest in motor neurons in lamina IX. Nuclear concentration also existed in neurons of lamina II, lamina VIII, lamina X and intermediate nucleus of the lateral column. The results indicate that these neurons are target neurons which contain nuclear receptors for 1,25(OH)2 vitamin D3. This suggests that 1,25(OH)2 vitamin D3 has direct genomic actions on the innervation of skeletal muscle by exerting related trophic, secretory, and electrophysiological effects. In addition, these data point to direct genomic actions of 1,25(OH)2 vitamin D3 on spinal sensory perception, and on certain autonomic functions. Nuclear binding in certain neurons in the peripheral ganglion of the trigeminal nerve further suggests that sensory perception is influenced by 1,25(OH)2 vitamin D3 not only at the level of the substantia gelatinosa, but also at the level of spinal ganglia.

Pyloric gastrin-producing cells and pyloric sphincter muscle cells are nuclear targets for 3H 1,25(OH)2 vitamin D3. Studied by autoradiography and immunohistochemistry

Autoradiographic studies were conducted to identify and characterize target cells for 1,25(OH)2 vitamin D3 in the pyloric region of rats and mice. After injection of 3H 1,25(OH)2 vitamin D3, nuclear concentration of radioactivity was observed in nuclei of duodenal epithelium and certain cells of pyloric glands, while most of the epithelial cells in the pyloric and gastric glands did not show nuclear labeling. In combined immunohistochemical studies, cells in the pyloric glands that showed nuclear concentration of radioactivity, were stained in their cytoplasm with antibodies to gastrin. Also, cells of the pyloric sphincter muscle showed nuclear labeling, in contrast to cells of the duodenal muscularis, which remained unlabeled under the conditions of the experiments. The results indicate that the cells with nuclear radioactivity contain receptors for 1,25(OH)2 vitamin D3 and suggest that gastrin secretion and pyloric muscle functions are regulated by a direct action of 1,25(OH)2 vitamin D3 on these cells.

Vitamin D sites of action in the pituitary studied by combined autoradiography-immunohistochemistry

Adult male and female mice under normal diet were injected with 3H 1,25(OH)2 vitamin D3 and sacrificed 3.5 h afterwards. Autoradiograms were prepared according to our thaw-mount technique and stained with antibodies to pituitary hormones. Thyrotropes showed strong and extensive nuclear concentration of radioactivity: about 90% of the immunostained thyrotropes were labeled. Lactotropes, somatotropes and gonadotropes showed no or only weak nuclear radioactivity: a subpopulation of 5%-10% of each of these immunostained cell types displayed nuclear labeling that was weak when compared to thyrotropes. Neural lobe pituicytes also showed weak to intermediate nuclear labeling. The results indicate a presence of nuclear receptors for 1,25(OH)2 vitamin D3 in pituitary cell types and suggest direct but differential genomic effects of 1,25(OH)2 vitamin D3 on pituitary hormone secretion. Evidence further suggests the existence of a vitamin D regulated brain-pituitary-thyroid axis.

Nuclear receptors for 1,25(OH)2 vitamin D3 in thymus reticular cells studied by autoradiography

After injection of 3H 1,25(OH)2 vitamin D3 to rats fed a vitamin D-deficient diet, nuclear concentration and retention of radioactivity exists in reticular cells of the thymus medulla and cortex, as well as outer cells of developing Hassal's corpuscles. Lymphocytes do not show nuclear concentration of radioactivity. Nuclear concentration in reticular cells is prevented by prior injection of excess 1,25(OH)2 vitamin D3. The results indicate that reticular-endothelial cells contain nuclear receptors for 1,25(OH)2 vitamin D3 and suggest that effects of 1,25(OH)2 vitamin D3 on immune response and lymphocyte differentiation are indirect and mediated through genomic modulation of reticular cell functions such as messenger secretion.

1,25 (OH)2 vitamin D3 sites of action in the brain. An autoradiographic study

After injection of 3H 1,25 (OH)2 vitamin D3 to adult rats and mice, under normal or vitamin D deficient diet, the hormone was found to be accumulated in nuclei of neurons in certain brain regions. Nuclear concentration was prevented or diminished, when excess unlabeled 1,25 (OH)2 vitamin D3 was injected before 3H 1,25 (OH)2 vitamin D3, while excess 25 (OH) vitamin D3 did not prevent nuclear labeling. Highest nuclear concentration of 3H 1,25 (OH)2 vitamin D3 is observed in certain neurons in the nucleus interstitialis striae terminalis, involving its septo-preoptic pars dorsolateralis and its anterior hypothalamic-thalamic portion, and in the nucleus centralis of the amygdala, all constituting a system of target neurons linked by a component of the stria terminalis. Nuclear concentration of 3H 1,25 (OH)2 vitamin D3 is also found in neurons in the periventricular nucleus of the preoptic-hypothalamic region, including its extensions, the parvocellular paraventricular and arcuate nucleus, in the ventromedial nucleus, supramammillary nucleus, reticular nucleus of the thalamus, ventral hippocampus, caudate nucleus, pallium, in the midbrain-pontine central gray, dorsal raphe nucleus, parabrachial nuclei, cranial motor nuclei, substantia gelatinosa of the sensory nucleus of the trigeminus, Golgi type II cells of the cerebellum, and others. The extensive distribution of target neurons suggests that 1,25 (OH)2 vitamin D3 regulates the production of several aminergic and peptidergic messengers, and influences the activity of certain endocrine-autonomic, sensory and motor systems.

Autoradiographic studies with 3H 1,25 dihydroxyvitamin D3 in thyroid and associated tissues of the neck region

Rats and mice fed a vitamin D-deficient or vitamin D-complete diet were injected with 3H 1,25 (OH)2 vitamin D3. Autoradiograms prepared from cross sections through the neck region revealed nuclear concentration of radioactivity strongest in parathyroid chief cells, occasionally in thyroid follicular epithelial and interfollicular cells, in the epithelium of tubular remnants of the ultimobranchial body, in epithelium of the esophagus, in chondrocytes of tracheal cartilage, and in myoepithelial cells of tracheal glands. In the thyroid, most of the follicle epithelial cells did not show nuclear concentration of radioactivity which occurred only occasionally and predominantly in follicles located in marginal positions. Thyroglobulin in lumina of thyroid follicles contained varying amounts of radioactivity that correspond to the diameter of the follicles, with relatively high amounts in large follicles and little or no radioactivity in small follicles. Competition with excess of unlabeled 1,25 (OH)2 vitamin D3 abolished nuclear radioactivity, but not the radioactivity in the colloid, while 25 (OH) vitamin D3 did not affect either. When a combination of autoradiography and immunohistochemistry was applied, follicular and parafollicular C-cells positive for calcitonin antibodies, did not show nuclear concentration of radioactivity. Tubular remnants of ultimobranchial bodies, however, showed distinct nuclear labeling, but did not stain, or only weakly stain, with antibodies to calcitonin. When 3H 25 (OH) vitamin D3 was injected, no nuclear concentration of radioactivity was noted in any of the tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization of Epstein-Barr virus-encoded small RNAs by in situ hybridization

Human B lymphocytes latently infected with Epstein-Barr virus (EBV) synthesize two low molecular weight RNAs designated EBER 1 and 2. Using an in situ hybridization technique we have localized EBER 1 and 2 within the nucleus of single EBV-harboring B lymphocytes from established and recently transformed cell lines. As controls, the locations of the small nuclear RNA, U1, and the small cytoplasmic RNA, 7SL, were examined in HeLa and EBV-harboring cells. Because of possible functional similarities between EBERs and the adenovirus-associated (VA) RNAs, VAI was also localized; it appeared to be in the nucleus and cytoplasm, implying that VAI may have a different role than that of the nuclear-localized EBERs.

Response to acute hCG stimulation and steroidogenic potential of Leydig cell fibroblastic precursors in humans

The process of early testosterone (T) secretion and Leydig cell differentiation in humans was studied to explore the steroidogenic capacity of Leydig cell fibroblastic precursors. Seven cryptorchid boys received hCG prior to orchidopexy. Patients CP, PB, and MR received one injection of 1000 IU; patients JR and GG, three daily injections of 1000 IU, and patients MP and MM, five daily injections of 1000 IU. A testicular biopsy was obtained at the time of operation, 24 hours after the last injection. Serum T (ng/dl) before and after hCG stimulation and testicular T (ng/g) were determined by RIA. A control prepubertal testis (tumoral orchidectomy) was incubated in vitro and showed a time-dependent accumulation of T both in the medium and the testicular tissue. Testosterone released into the medium at 1, 2, and 4 hours was 0.76, 1.43, and 4.03 ng/ml, respectively. Tissue T at 0, 1, 2, and 4 hours was 9, 11, 16, and 24 ng/g, respectively. This indicates synthesis and secretion of T into the medium. Control testes showed abundant fibroblastic precursors with scanty cytoplasm, few organelles, heterochromatic nuclei, and minute nucleoli. No Leydig cells were present. After 1 day of hCG stimulation, numerous fibroblasts were activated, displaying enlarged cytoplasms with increased numbers of organelles, nuclei rich in euchromatin, and bigger nucleoli. No Leydig cells were present. Basal serum testosterone was 58.2 +/- 45.3 ng/dl and 87.3 +/- 42.0 after hCG administration, while testicular T was 974.0 +/- 686.0 ng/g (control prepubertal testicular T is 10-50 ng/g). After 3 days of hCG, activated fibroblasts increased and immature Leydig cells appeared. Basal serum T was 35.5 +/- 7.8 ng/dl and 394.0 +/- 24.0 after hCG stimulation, while testicular T rose to 2797.5 +/- 1222.6 ng/g. After 5 days, mature Leydig cells appeared for the first time. Serum T was 58 +/- 59.3 ng/dl (basal) and 641.5 +/- 390 ng/dl (after hCG); testicular T was 789 ng/g (patient MM did not have a value for testicular T). HCG induced numerous coated pits and endocytic vesicles in activated fibroblasts and young Leydig cells, suggesting receptor aggregation and internalization of hormone-receptor complexes. Peroxidase-antiperoxidase (PAP) localization of T was positive in peritubular fibroblasts and Leydig cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Monosodium glutamate lesions in rat hypothalamus studied by immunohistochemistry for gonadotropin releasing hormone, neurotensin, tyrosine hydroxylase, and glutamic acid decarboxylase and by autoradiography for [3H] estradiol

Adult male and female rats treated neonatally with monosodium glutamate (MSG) exhibit lesions in the arcuate nucleus of the hypothalamus. Immunohistochemical analysis of the distribution of tyrosine hydroxylase (TH), glutamic acid decarboxylase (GAD), neurotensin (NT) and gonadotropin-releasing hormone (GnRH) reveals substantial destructions of tuberoinfundibular dopamine and NT systems accompanied by a marked reduction of immunoreactivity in the median eminence. GAD immunoreactivity in the arcuate nucleus and median eminence is greatly reduced, while GnRH containing structures in the mediobasal hypothalamus are not noticeably affected. Evaluation of autoradiograms after intravenously administered [3H] estradiol in the ventral hypothalamus indicate an almost complete loss of target neurons in the arcuate nucleus but not in the nearby ventromedial nucleus. The results suggest that: (a) NT- and dopamine-containing neurons of the arcuate nucleus project to the median eminence via tuberoinfundibular NT and dopaminergic pathways; (b) GABA in the median eminence originates to a major extent from neurons of the arcuate nucleus through a tuberoinfundibular GABAergic system; (c) GnRH is produced in the rat outside the arcuate nucleus; (d) the MSG-induced lesion in the basal tuberal region abolishes or strongly diminishes estradiol target neurons in the arcuate nucleus.

Localization of aldosterone and corticosterone in the central nervous system, assessed by quantitative autoradiography

Nuclear localization of tritiated aldosterone in the CNS was studied in rats by numerical evaluation of silver grains, deposited over neuronal cell nuclei in thaw-mounted autoradiograms, and compared with the localization obtained after prior administration of a 100-fold excess of radioinert aldosterone, corticosterone or 18-hydroxy-11-deoxycorticosterone (18-OH-DOC). Corticosterone and 18-OH-DOC completely prevented nuclear localization in most regions examined. However, in contrast to pretreatment with aldosterone, pretreatment with corticosterone and 18-OH-DOC did not completely prevent the concentration of radioactivity in the cell nuclei of the indusium griseum. Traces of radioactivity were, furthermore, retained in areas CA1 and CA2 and the dentate gyrus in rats exposed to corticosterone, but not to 18-OH-DOC, prior to [3H]aldosterone. A similar profile of silver grain distribution to that noted with aldosterone was found for corticosterone except that with tritiated corticosterone the most intense concentration of radioactivity occurred in hippocampal areas CA1 and CA2 and not in the indusium griseum. Prior administration of excess deoxycorticosterone acetate abolished nuclear accumulation of tritiated corticosterone. Dihydrotestosterone, on the other hand, failed to compete with tritiated corticosterone at a dose 200-fold in excess of the tritiated steroid. We conclude that (1) a receptor readily shared by aldosterone, corticosterone, 18-OH-DOC and DOC, but not by dihydrotestosterone, is widely distributed throughout the CNS, (2) a receptor shared by aldosterone and 18-OH-DOC, but not by corticosterone may be present in hippocampal areas CA1 and CA2, (3) that both these as well as the receptor accepting dihydrotestosterone can be located within the same cell.

Kindled seizure-induced reduction of muscarinic cholinergic receptors in rat hippocampal formation: evidence for localization to dentate granule cells

The binding of [3H] quinuclidinyl benzilate ( [3H] QNB) to muscarinic cholinergic receptors in dentate gyrus of rat hippocampal formation was analyzed by membrane binding assay and in vitro autoradiography. The destruction of dentate granule cells, either by neonatal irradiation or colchicine injection, resulted in nearly complete elimination of [3H] QNB binding sites in the molecular and granule cell layers. By contrast, neither perforant path transection nor destruction of the septal-hippocampal cholinergic afferents caused a decline of [3H] QNB binding sites. Amygdala kindled seizures resulted in a 30% reduction of [3H] QNB binding sites which was distributed uniformly across the entire molecular and granule cell layers. Thus, most, if not all, of the muscarinic cholinergic receptors present in dentate gyrus appear to reside on the somata and dendritic trees of the dentate granule cells. We propose that this kindled seizure-induced decline of muscarinic receptors represents an endogenous compensatory mechanism designed to stabilize granule cell excitability.

Target cells for 1,25-dihydroxyvitamin D3 in intestinal tract, stomach, kidney, skin, pituitary, and parathyroid

After mature rats that had been fed on a vitamin D3-deficient diet were injected with tritium-labeled 1,25-dihydroxyvitamin D3, radioactivity became concentrated in nuclei of luminal and cryptal epithelium of the duodenum, jejunum, ileum, and colon; in nuclei of the epithelium of kidney distal tubules including the macula densa, and in podocytes of glomeruli; in nuclei of the epidermis including outer hairshafts and sebaceous glands; and in nuclei of certain cells of the stomach, anterior and posterior pituitary, and parathyroid. These results reveal cell types that contain receptors for 1,25-dihydroxyvitamin D3 or metabolites of this compound both in known or hypothesized target tissues and in tissues that were previously unknown to participate in vitamin D3 metabolism.

Passage of Amipaque (metrizamide) through the arachnoid granulations

125I labelled Amipaque (metrizamide) was introduced by cisternal puncture into six rabbits and perfused at various pressures. The torcular was exposed, frozen rapidly, and excised intact. Sections of arachnoid proliferations were made from the frozen specimen and either freeze dried or sandwiched directly for autoradiography. Some specimens were freeze dried en bloc prior to sectioning and sandwiching. All sections were exposed for 2-3 weeks at -80 degrees C prior to development of the autoradiographs. On microscopic examinations of the autoradiographs most of the activity was in the tubules or between cells suggesting intercellular passage. Some label was also present within the brain. The significance of this is discussed.

Androgen concentration in motor neurons of cranial nerves and spinal cord

After injection of [3H]dihydrotestosterone, a major testosterone metabolite, radioactivity is concentrated in nuclei of certain cells in the midbrain, pons, medulla oblongata, cerebellum, and spinal cord. While there is some overlap between androgen and estrogen target neuron distribution, certain motor neurons appear to be selectively labeled by androgen; in contrast, estrogen localization prevails in sensory neurons. These results may help to explain why male sexual behavior in some rodents is not fully activated with dihydrotestosterone alone but in addition requires estradiol, a testosterone metabolite.