Quantitative image analysis with densitometry for immunohistochemistry and autoradiography of receptor binding sites--methodological considerations

Reciprocal Regulatory Interaction between TRPV1 and Kinin B1 Receptor in a Rat Neuropathic Pain Model

Kinins are mediators of pain and inflammation and evidence suggests that the inducible kinin B1 receptor (B1R) is involved in neuropathic pain (NP). This study investigates whether B1R and TRPV1 are colocalized on nociceptors and/or astrocytes to enable regulatory interaction either directly or through the cytokine pathway (IL-1β, TNF-α) in NP. Sprague Dawley rats were subjected to unilateral partial sciatic nerve ligation (PSNL) and treated from 14 to 21 days post-PSNL with antagonists of B1R (SSR240612, 10 mg·kg^-1, i.p.) or TRPV1 (SB366791, 1 mg·kg^-1, i.p.). The impact of these treatments was assessed on nociceptive behavior and mRNA expression of B1R, TRPV1, TNF-α, and IL-1β. Localization on primary sensory fibers, astrocytes, and microglia was determined by immunofluorescence in the lumbar spinal cord and dorsal root ganglion (DRG). Both antagonists suppressed PSNL-induced thermal hyperalgesia, but only SB366791 blunted mechanical and cold allodynia. SSR240612 reversed PSNL-induced enhanced protein and mRNA expression of B1R and TRPV1 mRNA levels in spinal cord while SB366791 further increased B1R mRNA/protein expression. B1R and TRPV1 were found in non-peptide sensory fibers and astrocytes, and colocalized in the spinal dorsal horn and DRG, notably with IL-1β on astrocytes. IL-1β mRNA further increased under B1R or TRPV1 antagonism. Data suggest that B1R and TRPV1 contribute to thermal hyperalgesia and play a distinctive role in allodynia associated with NP. Close interaction and reciprocal regulatory mechanism are suggested between B1R and TRPV1 on astrocytes and nociceptors in NP.

Tracing Dietary Mercury Histochemically, with Autometallography, through the Liver to the Ovaries and Spawned Eggs of the Spot, a Temperate Coastal Marine Fish

Exposure to mercury (Hg) results in reproductive abnormalities and deficiencies in female fish. We traced the maternal assimilation and redistribution of dietary inorganic (HgII) and organic (MeHg) forms of Hg in a coastal marine fish, the Spot Leiostomus xanthurus. We conducted a 90-d laboratory experiment in which treatment Spot were fed muscle of Blue Marlin Makaira nigricans with elevated concentrations of Hg mixed with a commercial fish food, while control Spot were fed only commercial food pellets. Gonadal maturation was induced by shortening the photoperiod and increasing the temperature. Spawning was induced by intramuscular injection of human chorionic gonadotropin at 100 IU/kg. Solid-sampling atomic absorption spectrophotometry measured the total Hg (THg), HgII, and MeHg in Blue Marlin muscle. Autometallography located Hg-sulfide granules in the liver, ovaries, and spawned eggs, and densitometry provided comparisons of Hg-sulfide granules in the ovaries of treatment and control Spot. Overall, the intensity and prevalence of Hg-sulfide granules were greater in the liver, ovaries, and eggs from treatment Spot than in those from controls. The tissue and cellular distribution of Hg-sulfide granules differed. Received November 18, 2016; accepted June 18, 2017.

Cytoskeletal proteins in the follicular wall of normal andcystic ovaries of sows

The expression of cytoskeletal proteins was evaluated immunohistochemically in 36 normal ovaries sampled from 18 sows and 44 cystic ovaries sampled from of 22 sows, was evaluated. All sows had history of reproductive problems, such as infertility or subfertility. The immunohistochemically stained area (IHCSA) was quantified through image analysis to evaluate the expression of these proteins in the follicular wall of secondary, tertiary, and cystic follicles. Cytokeratins (CK) immunoreactivity was strong in the granulosa cell layer (GC) and mild in the theca interna (TI) and externa (TE) of the normal follicles. There was severe reduction of the reaction to CK in the GC in the cystic follicles, mainly in the luteinized cysts. The immunoreactivity for vimentin was higher in the GC from normal and cystic follicles in contrast with the other follicular structures. In the luteinized cysts, the IHCSA for vimentin was significantly higher in TI and in both observed cysts, the labeling was more accentuated in TE. Immunohistochemical detection of desmin and α-SMA was restricted to the TE, without differences between the normal and cystic follicles. The results of the current study show that the development of ovarian cysts in sows is associated to changes in the expression of the cytoskeletal proteins CK and vimentin.

Developmental programming: effect of prenatal steroid excess on intraovarian components of insulin signaling pathway and related proteins in sheep

Prenatal testosterone (T) excess increases ovarian follicular recruitment, follicular persistence, insulin resistance, and compensatory hyperinsulinemia. Considering the importance of insulin in ovarian physiology, in this study, using prenatal T- and dihydrotestosterone (DHT, a nonaromatizable androgen)-treated female sheep, we tested the hypothesis that prenatal androgen excess alters the intraovarian insulin signaling cascade and metabolic mediators that have an impact on insulin signaling. Changes in ovarian insulin receptor (INSRB), insulin receptor substrate 1 (IRS1), mammalian target of rapamycin (MTOR), phosphatidylinositol 3-kinase (PIK3), peroxisome proliferator-activated receptor-gamma (PPARG), and adiponectin proteins were determined at fetal (Days 90 and 140), postpubertal (10 mo), and adult (21 mo) ages by immunohistochemistry. Results indicated that these proteins were expressed in granulosa, theca, and stromal compartments, with INSRB, IRS1, PPARG, and adiponectin increasing in parallel with advanced follicular differentiation. Importantly, prenatal T excess induced age-specific changes in PPARG and adiponectin expression, with increased PPARG expression evident during fetal life and decreased antral follicular adiponectin expression during adult life. Comparison of developmental changes in prenatal T and DHT-treated females found that the effects on PPARG were programmed by androgenic actions of T, whereas the effects on adiponectin were likely by its estrogenic action. These results suggest a role for PPARG in the programming of ovarian disruptions by prenatal T excess, including a decrease in antral follicular adiponectin expression and a contributory role for adiponectin in follicular persistence and ovulatory failure.

Quantitative changes in calretinin immunostaining in the cochlear nuclei after unilateral cochlear removal in young ferrets

Neurons of the cochlear nuclei receive axosomatic endings from primary afferent fibers from the cochlea and have projections that diverge to form parallel ascending auditory pathways. These cells are characterized by neurochemical phenotypes such as levels of calretinin. To test whether or not early deafferentation results in changes in calretinin immunostaining in the cochlear nucleus, unilateral cochlear ablations were performed in ferrets soon after hearing onset (postnatal day [P]30-P40). Two months later, changes in calretinin immunostaining as well as cell size, volume, and synaptophysin immunostaining were assessed in the anteroventral (AVCN), posteroventral (PVCN), and dorsal cochlear nucleus (DCN). A decrease in calretinin immunostaining was evident ipsilaterally within the AVCN and PVCN but not in the DCN. Further analysis revealed a decrease both in the calretinin-immunostained neuropil and in the calretinin-immunostained area within AVCN and PVCN neurons. These declines were accompanied by significant ipsilateral decreases in volume as well as neuron area in the AVCN and PVCN compared with the contralateral cochlear nucleus and unoperated animals, but not compared with the DCN. In addition, there was a significant contralateral increase in calretinin-immunostained area within AVCN and PVCN neurons compared with control animals. Finally, a decrease in area of synaptophysin immunostaining in both the ipsilateral AVCN and PVCN without changes in the number of boutons was found. The present data demonstrate that unilateral cochlear ablation leads to 1) decreased immunostaining of the neuropil in the AVCN and PVCN ipsilaterally, 2) decreased calretinin immunostaining within AVCN and PVCN neurons ipsilaterally, 3) synaptogenesis in the AVCN and PVCN ipsilaterally, and 4) increased calretinin immunostaining within AVCN and PVCN neurons contralaterally.

Ovarian hormone influences on the density of immunoreactivity for tyrosine hydroxylase and serotonin in the primate corpus striatum

The serotonergic and dopaminergic inputs to the corpus striatum in human and non-human primates participate in diverse sensorimotor, cognitive, and affective functions, are implicated in dysfunction in diseases such as Parkinson's disease and schizophrenia, and are targets for many of the drugs used to treat these disorders. Sex differences in the incidence and/or clinical course of these disorders and in the effectiveness of related dopaminergic and serotonergic drug therapies suggest that primate striatal indolamines and catecholamines are also influenced by gonadal hormones. However, while well studied in rats, relatively little is known about precisely how gonadal steroids modulate stratial dopamine and serotonin systems in primates. To begin to address this issue, the present studies explored the effects of ovarian steroids on the serotonergic and dopaminergic innervation densities of the caudate, putamen, and the nucleus accumbens in young adult rhesus monkeys. Using densitometry to quantify immunoreactivity for serotonin and for the catecholamine-synthesizing enzyme tyrosine hydroxylase, innervation densities were compared in identified, functionally specialized striatal subdomains across animals that were either ovariectomized or ovariectomized and supplemented with estradiol and/or progesterone, i.e. in a primate model of surgical menopause, with and without hormone replacement therapy. These analyses revealed clear examples of structure-, hemisphere-, and replacement regimen-specific effects of changes in circulating steroids on the densities of each afferent system examined. Further, the predominantly stimulatory effects observed occurred in striatal areas analogous to those suspected as sites of localized dopamine and/or serotonin compromise in Parkinson's disease and schizophrenia. Thus, the hormone actions identified in this study could hold relevance for some of the sex differences identified in relation to these disorders, including the findings of decreased incidence and/or symptom severity in women that have led to hypotheses of protective effects for estrogen.

Bone-implant interface around titanium implants under different loading conditions: a histomorphometrical analysis in the Macaca fascicularis monkey

BACKGROUND

Bone healing around endosseous dental implants is associated with peri-implant loading conditions. Therefore, the aim of this study was to evaluate histomorphometrically the bone response around unloaded, delayed, and immediately loaded implants with a progressive thread design that were placed in the posterior regions of the lower jaw in monkeys.

METHODS

Nine adult monkeys (Macaca fascicularis) were used in this study. After extraction of the second premolars and first and second molars in the mandible, the bone was allowed to heal for a period of 3 months. Forty-eight 8 mm long implants with a diameter of 3.5 mm were placed according to the following protocol. In two of the monkeys, six implants were placed and left to heal submerged for 3 months (group A). In seven monkeys, 21 implants were placed in one side of the mandible and loaded after 3 months of submerged healing (group B). The group B implants were loaded with temporary resin bridges at the same time as another 21 implants that were loaded immediately (group C) after placement in the contralateral side of the mandibles of the same monkeys. The occlusion of group B and C implants was checked for optimal relationship of the resin bridges that were replaced 1 month later with metal bridges and loaded for an additional 2 months. The group A animals were sacrificed after 3 months of submerged healing without loading; group B and C animals were sacrificed after 3 months of implant loading. Specimens were examined histologically and histomorphometrically.

RESULTS

All implants osseointegrated without presenting any gap in the metal-bone interface. Compact cortical bone was found in contact with the implant surfaces. Group A implants demonstrated in the interface cancellous bone with loose connective tissue. Group B and C implants showed a thick cortical plate with extensive bone trabeculae formation. There was a significant difference in bone-to-implant contact (BIC) between the various loading conditions. No significant difference (P < 0.05) was found between groups B and C. There was an increased area of bone (BA) within the threads as well as around the apices of group B and C implants.

CONCLUSIONS

Implant loading might have stimulated increased bone formation and thus may be a key factor in influencing positive osseointegration. In addition, immediately loaded implants may osseointegrate in a similar manner as delayed loaded implants.

Immunohistochemistry as a tool for topographical semi-quantification of neurotransmitters in the brain

Immunohistochemistry is a powerful tool to detect neurotransmitter (NT) presence in different brain structures with a high spatial resolution. However, it is only scarcely used in quantitative approach due to lack of reproducibility and sensitivity. We developed a protocol of NT detection based on immunohistochemistry and image analysis to show that this approach could also be useful to evaluate NT content variations. We focused our study on the GABAergic system in the cerebellum and measured different accurate parameters, namely the optical density (O.D.), the stained area and the number of immunoreactive cells in each cerebellar cell layer. In order to modify the GABA content, we used gamma-vinyl-GABA (GVG), an inhibitor of GABA-transaminase, known to dramatically increase GABA concentration in the central nervous system (CNS) and especially in the cerebellum. We observed a significant increase in the three parameters measured in the molecular and the granular layers of the cerebellum after treatment with GVG, reflecting the well-established increase in GABA content after such a treatment. Therefore, our technical approach allows not only a precise determination of the effects in particular cell layers but also a semi-quantification of GABA content variations. This technique could be suitable for monitoring NT variations following any treatment.

Effects of radiofrequency exposure on the GABAergic system in the rat cerebellum: clues from semi-quantitative immunohistochemistry

The widespread use of cellular phones raises the problem of interaction of electromagnetic fields with the central nervous system (CNS). In order to measure these effects on neurotransmitter content in the CNS, we developed a protocol of neurotransmitter detection based on immunohistochemistry and image analysis. Gamma-vinyl-GABA (GVG), an inhibitor of the GABA-transaminase was injected in rats to increase GABA concentration in the CNS. The cellular GABA contents were then revealed by immunohistochemistry and semi-quantified by image analysis thanks to three parameters: optical density (O.D.), staining area, and number of positive cells. The increase in cerebellar GABA content induced by GVG 1200 mg/kg was reflected in these three parameters in the molecular and the granular layers. Therefore, control of immunohistochemistry parameters, together with appropriate image analysis, allowed both the location and the detection of variations in cellular neurotransmitter content. This protocol was used to investigate the effects of exposure to 900 MHz radiofrequencies on cerebellar GABA content. Both pulsed emission with a specific absorption rate (SAR) of 4 W/kg and continuous emission with high SAR (32 W/kg) were tested. We observed a selective diminution of the stained processes area in the Purkinje cell layer after exposure to pulsed radiofrequency and, in addition, a decrease in O.D. in the three cell layers after exposure to continuous waves. Whether this effect is, at least partly, due to a local heating of the tissues is not known. Overall, it appears that high energetic radiofrequency exposure induces a diminution in cellular GABA content in the cerebellum.

A semiquantitative image-analytical method for the recording of dose-response curves in immunocytochemical preparations

Knowledge about intracellular signal transduction cascades is largely based on investigations of cultured cells whose responses to different stimuli are typically quantified via RIA, ELISA, or immunoblots. These techniques, which require relatively large amounts of biological material, are performed with homogenized cells and therefore do not allow localization of the molecules under investigation. We describe a protocol for recording dose-response curves directly from immunocytochemical preparations using rat pinealocytes as a model system. The cells were exposed to beta-adrenergic stimuli inducing the phosphorylation of the transcription factor CREB (mediated by PKA), an increase in ICER protein levels, and synthesis and release of melatonin. Melatonin concentrations were determined by ELISA. cPKA, phosphorylated CREB, and ICER were demonstrated by immunocytochemistry and immunoblots. Dose-response curves were recorded by measuring the integrated density of the immunoreactive sites with an image analysis program. Dose-response curves from immunoblots and immunocytochemical preparations showed almost identical dynamics, validating the immunocytochemical approach, which minimizes the amount of biological material needed for such studies, allows combined quantification and localization of biomolecules, and may even be more sensitive than immunoblotting.

Complex regulation of the expression of the polysialylated form of the neuronal cell adhesion molecule by glucocorticoids in the rat hippocampus

The gyrus dentatus is one of the few areas of the brain that continues to produce neurons after birth. The newborn cells differentiate into granule cells which project axons to their postsynaptic targets. This step is accompanied by the transient expression of the polysialylated isoforms of neuronal cell adhesion molecules (PSA-NCAM) by the developing neurons. Glucocorticoid hormones have been shown to inhibit neurogenesis. We noted a functional correlation between PSA-NCAM expression and glucocorticoid action after manipulation of corticosterone levels in the adrenalectomized rat. Adrenalectomy increased neurogenesis, evaluated from the incorporation of 5-bromo-2'-deoxyuridine in neuronal precursors, as well as PSA-NCAM expression. The increase in PSA-NCAM-immunoreactive (IR) cells in the gyrus dentatus, evidenced 72 h following adrenalectomy, persisted for at least a month. It was accompanied by enhanced dendritic arborization of PSA-NCAM-IR cells in the gyrus dentatus and by an increase in number of PSA-NCAM-IR fibres in the CA3 subfield. Neurogenesis was normalized by restitution of diurnal or nocturnal levels of corticosterone, whereas normalization of PSA-NCAM expression was only observed after simulation of the complete circadian fluctuation of the hormone. Our findings reveal the complex action of corticosterone in modulating the expression of PSA-NCAM in the gyrus dentatus of the hippocampal formation. They also highlight the importance of corticosterone fluctuations in the control of neurogenesis and plasticity in this structure.

The overall rod performance test in the MPTP-treated-mouse model of Parkinsonism

We investigated the usefulness of the Overall Rotarod Performance (ORP) test for evaluating overall locomotory ability in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-injected-mouse model of Parkinson's disease (PD). For this procedure, the mice are pretrained on the rotarod and then tested at a series of increasing speeds, recording the time that the animal remains on the rod at each speed; the overall rod performance (ORP) of each animal is then calculated as the area under the curve in a plot of time-on-the-rod against rotation speed. At 15-day intervals, C57BL/6 mice were injected (or sham-injected) with MPTP, with ORP testing 7-10 days after each injection. After the fourth injection (day 45), mice in the treated group showed clearly lower ORP than mice in the control group (70-90% reduction in ORP), and were thus considered effectively lesioned. Subsequently, we investigated the short-term effects of apomorphine and L-DOPA on ORP in MPTP-treated mice. Apomorphine (at 0.5 or 2.5 mg/kg) had no significant effect, while L-DOPA (at 80 but not at 40 mg/kg) caused almost complete short-term recovery of pretreatment ORP. By about 100 days after the last MPTP injection, MPTP-treated mice showed partial long-term recovery of ORP; at this stage the mice were killed for tyrosine hydroxylase (TH) immunohistochemistry studies. TH immunoreactivity in the striatum showed a strong positive correlation with ORP as tested on day 100. We conclude that the ORP test is useful for evaluating motor deficit in MPTP-treated mice, and the effects of subsequent treatments.

Drug-free evaluation of rat models of parkinsonism and nigral grafts using a new automated rotarod test

A variety of tests are available for the evaluation of behavioural deficits in rat models of hemiparkinsonism; many, however, are of limited applicability or insufficiently objective. The drug-induced turning behaviour test is widely used. A disadvantage of this test is that the use of drugs may lead to misleading results. Here, we describe a drug-free rotarod test that was used to evaluate the effects of unilateral 6-hydroxydopamine lesions, nigral grafts, and subrotational doses of apomorphine. The rotarod unit was automated and interfaced to a personal computer allowing automatic recording of the time that each rat was able to stay on the rod at different rotational speeds (i.e., progressively increasing the difficulty of the task). A combination of lesion-induced deficits resembling those of Parkinson's disease appears to be involved in falling from the rod. The test shows high effectiveness for identifying rats with maximal dopaminergic lesions, but is also effective for identifying partial lesions. Rotarod performance profiles were useful for investigating the effects of intrastriatal nigral grafts, since low rotation speeds revealed differences from lesioned rats (i.e., improvements) while higher speeds revealed differences from normal rats (i.e., remaining deficits and partial lesions). The test was effective regardless of whether rats were trained on the rod before lesion, after lesion, or after grafting. Injections of apomorphine (0.0125 and 0.0250 mg/kg) did not induce consistent improvements. These results indicate that the rotarod test is a useful drug-free procedure for overall evaluation of basic motor abilities in rat models of parkinsonism and treatment-induced changes.

Unilateral eyeball enucleation differentially alters AMPA-, NMDA- and kainate glutamate receptor binding in the newborn rat brain

The aim of the present work was to evaluate the neurochemical effects of early unilateral visual deprivation as a model of impaired visual maturation. For this purpose, binding to the different ionotropic glutamate receptor subtypes was quantified in vision-related and vision-unrelated brain structures of control and unilaterally deprived newborn rats. At post-natal (PN) day 10, male Sprague-Dawley rats underwent either unilateral eyeball enucleation (enucleation group, n = 12) or sham operation (control group, n = 12). In each group, brains were obtained either at post-natal day 20 (n = 6) or post-natal day 30 (n = 6) and processed for quantitative in vitro autoradiography selective for NMDA, kainate, and AMPA glutamate-binding sites, as well as for the presynaptic adenosine A1 receptor as a control of the deafferentation efficacy. In control animals, quantitative autoradiography revealed an increase in NMDA (e.g. +45% in superior colliculus) and kainate receptor binding (e.g. +55% in visual cortex, layer IV) from post-natal day 20 to post-natal day 30, associated with stable levels of AMPA receptor binding, in the vision-related structures. In the deafferented visual structures, monocular enucleation induced a marked decrease in A1 site density (e.g. -38 to -52%, in the superficial layer of superior colliculi, at PN day 20 and PN day 30, respectively) in parallel with a mild increase in both NMDA (e.g. +8 to 9%, in superior colliculi and visual cortex, layer IV at PN day 30, respectively) and AMPA (e.g. +16%, in layer IV of the visual cortex at PN day 30). Superimposed on marked bilateral decreases at PN day 30 in the enucleated rats, kainate receptor binding also revealed a slight but significant decrease (-5%) in the deafferented superior colliculus as compared to the non-deafferented side. The present findings (different time-courses of, and differential effects of deafferentation on, the NMDA, kainate and AMPA glutamate receptor subtypes throughout the visual brain structures) further support the involvement of these receptors in distinctive roles during maturation of the visual system.

Effects of long-term hypoxia on tyrosine hydroxylase protein content in catecholaminergic rat brainstem areas: a quantitative autoradiographic study

The nucleus tractus solitarius (NTS), the ventrolateral medulla (VLM), the dorsal motor vagus nucleus (DMnX) and the locus coeruleus (LC) are catecholaminergic brainstem areas involved in ventilatory and cardiovascular responses to hypoxia and tyrosine hydroxylation is the rate limiting step of cathecholamine biosynthesis in the central nervous system. The aim of this study was to evaluate the effects of long-term hypoxia on tyrosine hydroxylase (TH) content in these different areas using a quantitative autoradiographic technique. Two experimental groups of rats were studied: Group I (9 males, 8 females) was submitted to normobaric hypoxia (10% O2-90% N2) for 21 days and compared to 12 (6 males, 6 females) normoxic control rats (Group II). Coronal tissue sections from fresh-frozen rat brains, obtained along the caudo-rostral axis, were incubated in the presence of a TH monoclonal antibody, and the reaction was revealed by a 35S-labelled secondary antibody. TH levels were quantified in the NTS, VLM, DMnX and LC by measuring optical density on autoradiographic films using an automatic image analyser system. Regional antigen quantification was assessed by computer-assisted image analysis. Chronic hypoxia led to body weight decrease until day 5, haematocrit increase (65 +/- 2% vs. 44 +/- 2%, P < 0.01) and right ventricle hypertrophy (35 +/- 0.5% vs. 23 +/- 0.1% of the weight of the two ventricles, P < 0.01). TH protein contents expressed as percentage of controls were as follows. In males, in the rostral part of the NTS 132 +/- 9% (P < 0.02), in the caudal part of the NTS, 117 +/- 5% (P < 0.04). In female rats, the TH quantity reached a value of 124 +/- 4% (P < 0.01) in the rostral part and 126 +/- 6% (P < 0.01) in the caudal part of the NTS. In females, TH content was significantly increased in the VLM, 124 +/- 6%, P = 0.01, whereas in males there was only a non-significant trend to increase, 122 +/- 11%. In females, there was a significant increase in the DMnX, 127 +/- 9%, P = 0.05, whereas in males there was only a trend to increase, 120 +/- 5%. This study shows that long-term hypoxia induces a persistent increase in TH protein content both in the caudal and rostral part of the NTS, which are known to receive respectively chemo- and barosensory inputs, and in other catecholaminergic areas involved in baroreflex activity. Our data clearly demonstrate the implication of neurochemical mechanisms in the central relationship between chemo- and baroreflex which are responsible for changes in systemic arterial pressure and oxygen partial pressure as required for maintaining an adequate oxygen supply to the tissues.

Regional study of spinal alpha 2-adrenoceptor densities after intraspinal noradrenergic-rich implants on adult rats bearing complete spinal cord transection or selective chemical noradrenergic denervation

One of the challenges of restorative neuronal transplantation in the CNS of mammals is the appropriate integration of grafted cells in the host circuitry. One key parameter is the specific influence of grafted cells upon corresponding receptors. In order to test this issue on the lesioned spinal cord of adult rats, two models of spinal cord denervation were used: the first one consisted of a complete transection 1 week prior to an intraspinal transplantation of embryonic locus coeruleus (LC) primordia cell suspension; the second one was a chemical destruction of the spinal noradrenergic (NA) system 1 month prior to a similar transplantation. Five weeks after transplantation, spinal sections were processed for autoradiographic quantification of alpha 2-adrenoceptor binding sites densities. In most regions, alpha 2-adrenoceptor densities remained comparable or higher than before graft; interestingly, in lumbar dorsal horn, lumbar intermediate zone and sacral distal dorsal horn of transected-grafted rats, they returned to control level. Results are discussed in relation to the parallel study performed concerning alpha 1-adrenoceptors.

Decreased synaptophysin in the medial temporal lobe in schizophrenia demonstrated using immunoautoradiography

Synaptic alterations have been suggested, largely on theoretical grounds, to occur in the brain in schizophrenia. The messenger RNA encoding synaptophysin, a presynaptic terminal protein, is reduced in the medial temporal lobe in the disease, but immunocytochemical and immunoblotting data have not produced clear evidence for a loss of the encoded protein. Here we have used immunoautoradiography with an antisynaptophysin monoclonal antibody and a 35S-labelled secondary antibody in medial temporal lobe sections from 11 schizophrenics and 14 matched controls. In the schizophrenic cases there was an overall loss of synaptophysin (P < 0.02). Analysis by subfield showed significant reductions in the right dentate gyrus molecular layer, subiculum and parahippocampal gyrus, with similar trends in most other subfields. These data confirm that synaptophysin expression is decreased within the medial temporal lobe in schizophrenia. In the respect that synaptophysin is a marker of synaptic density, our findings suggest that reduced synaptic density may be a feature of the molecular neuropathology of the disease.

Intraspinal noradrenergic-rich implants reverse the increase of alpha 1 adrenoceptors densities caused by complete spinal cord transection or selective chemical denervation: a quantitative autoradiographic study

This study examined, in the adult rat, whether the intraspinal transplantation of a cell suspension of embryonic day (ED)13 rat locus coeruleus primordia was able to normalize the lesion-induced increase of spinal alpha 1-adrenoceptors. Two experimental models of spinal denervation were studied. The first model consisted of a complete spinal cord transection (thoracic vertebrae level T8-T9) and 1 week later, the cell suspension was transplanted below the section; the second one was obtained by a selective chemical lesion of the noradrenergic (NA) system and one month later, the cell suspension was implanted at the same level as in transected rats. Five weeks after grafting, all animals were sacrificed and spinal cord tissue sections were processed for immunohistochemical detection of noradrenaline or for quantification of alpha 1-adrenoceptors binding sites densities using [3H]prazosin as a ligand. After 6-OHDA lesion, as well as caudally to the transection, a significant increase by 21% (P < 0.01) to 68% (P < 0.001) of alpha 1-adrenoceptors densities was detected. The implantation of embryonic NA neurons into the denervated spinal cord led to a reversal of the lesion-induced increase of spinal alpha 1-adrenoceptors, five weeks later. Moreover, this reversal seems to be more effective after mechanical than after chemical denervation.

Selective quantitative analysis of the intensity of immunohistochemical reactions

The present study reports a new method for the densitometric measurement of the intensity of immunohistochemical reactions. This method is based on a programm for the Kontron VIDAS image analysis system and has been designed for the measurement of small differences in the relative intensity of immunohistochemical reactions. Immunohistochemistry was performed with the avidin-biotin-peroxidase complex and diaminobenzidine-HCl and H2O2 for enzyme visualization. Several methods for shade correction and image processing were elaborated. The study was carried out on gerbil Purkinje cells using monoclonal antibodies raised against calbindin D28k. Prerequesites of correct measurement were standardized preparation, i.e., identical thickness of the paraffin sections, identical performance of immunohistochemistry, and avoidance of any counterstaining. The evaluation of small intensity differences of immunohistochemical reactions was found to be feasible either by substractive shade correction and standardized normalization or by shade correction by division by a reference image and standardized thresholding. Small differences in antigen concentration were not detectable without additional image processing.

Normal distribution of alpha 2-adrenoceptors in the rat spinal cord and its modification after noradrenergic denervation: a quantitative autoradiographic study

The distribution of alpha 2 (alpha 2)-adrenoceptors along cervical, thoracic, lumbar, and sacral segments of the spinal cord of normal rats has been studied by quantitative autoradiography using the specific alpha 2-antagonist [3H]rauwolscine as a ligand. In addition, the influence of noradrenergic (NA) denervation [obtained either by complete transection of the spinal cord at vertebrae level T8-T9 or by selective lesion of NA spinal cord system carried out by intracisternal injection of 6-hydroxydopamine (6-OHDA)] on eventual variations of alpha 2-adrenoceptor density at spinal cord target cells was studied in parallel. In control rats, the quantitative analysis of alpha 2-adrenoceptor densities revealed the presence of these receptors throughout the whole gray matter with a preferential location in the superficial dorsal horn. This pattern was the same at all rostro-caudal levels of the cord and appeared very well correlated with the distribution of NA terminals revealed by immunohistochemistry, particularly in the superficial layers of the dorsal horn. After total transection of the spinal cord (caudally to the section) and 6-OHDA-induced lesion, an increase of alpha 2-adrenoceptor density was mainly observed within the distal dorsal horn thus evidencing supersensitivity in this area, while modifications were not detectable in other regions of the spinal gray matter, except at the lumbar level where other dorsal, central, and intermediate zones were significantly enriched.

Immunocytochemical quantification of tyrosine hydroxylase at a cellular level in the mesencephalon of control subjects and patients with Parkinson's and Alzheimer's disease

Parkinson's disease is characterized by massive degeneration of the melanized dopaminergic neurons in the substantia nigra. The functional capacity of the surviving nigral neurons is affected, as indicated by the subnormal levels of tyrosine hydroxylase (TH) mRNA in these neurons and the presence in the parkinsonian mesencephalon of melanized neurons lacking TH immunoreactivity. This is apparently in contraction with the known overactivity of dopamine synthesis and release that occurs in the remaining dopaminergic terminals. To test the ability of the surviving neurons to express TH protein, a semiquantitative immunocytochemical method was developed. The relative amounts of TH were estimated with a computer-assisted image analysis system in the dopaminergic neurons of representative mesencephalic sections of control and parkinsonian brains and for comparison in brains from patients with Alzheimer's disease. In control brains, the mean TH content per neuron differed from one subject to another and between the different dopaminergic cell groups of the mesencephalon in the same subject. Within a given dopaminergic region, the level of TH was variable among neurons. In patients with Parkinson's disease, the ratio of TH protein content per neuron in the substantia nigra by reference to that of the central gray substance was reduced. In patients with Alzheimer's disease, the amount of TH was selectively reduced in the remaining dopaminergic neurons of the ventral tegmental area, a region characterized by a loss in dopaminergic neurons. The decrease in cellular TH content might therefore be related to the presence of the neurodegenerative process in the area considered. In patients with Parkinson's disease, the incapacity of the surviving neurons to express normal TH levels may reduce the efficiency of the hyperactivity mechanisms that develop in the remaining striatal dopaminergic terminals.

Cellular quantification of tyrosine hydroxylase in the rat brain by immunoautoradiography

We developed a rapid and sensitive radioimmunohistochemical method for the quantification of tyrosine hydroxylase (TH) at both the anatomical and cellular level. Coronal tissue sections from fresh-frozen rat brains were incubated in the presence of a TH monoclonal antibody. The reaction was revealed with a 35S-labeled secondary antibody. TH content was quantified in catecholaminergic brain areas by measuring optical density on autoradiographic films or silver grain density on autoradiographic emulsion-coated sections. Regional TH concentrations determined in the locus ceruleus (LC), substantia nigra pars compacta (SNC), and ventral tegmental area (VTA) were significantly increased by 45% after reserpine treatment in the LC but unchanged in the SNC and VTA. Microscopic examination of TH radioimmunolabeling showed a heavy accumulation of silver grains over catecholaminergic cell bodies. In the LC, grain density per cell was heterogeneous and higher in the ventral than in the dorsal part of the structure. After reserpine treatment, TH levels were significantly increased (57%) in the neurons of the LC but not in those of the SNC or VTA. The data support the validity of this radioimmunohistochemical method as a tool for quantifying TH protein at the cellular level and they confirm that TH protein content is differentially regulated in noradrenergic and dopaminergic neurons in response to reserpine.

Cholecystokinin receptor density in the striatum of the spontaneously hypertensive rat

The possibility that cholecystokinin in the striatum may be involved in hypertension was investigated using in vitro receptor autoradiography. The binding density of 125I-Bolton Hunter labeled cholecystokinin octapeptide (125I-BH-CCK8) was determined using computer-assisted densitometry in the striatum of the spontaneously hypertensive rat (SHR) and its control the Wistar-Kyoto rat (WKY). A significant increase in 125I-BH-CCK8 binding density was found in the lateral part of the caudate-putamen of the SHR. In contrast, a significant decrease in 125I-BH-CCK8 binding density was found in the posteromedial nucleus accumbens of the SHR. These results indicate that CCK8 receptor density is altered in the striatum of the SHR and suggest a role for CCK8 receptors in the pathophysiology of hypertension.

Intrastriatal transplants of embryonic dopaminergic neurons counteract the increase of striatal enkephalin immunostaining but not serotoninergic sprouting elicited by a neonatal lesion of the nigrostriatal dopaminergic pathway

The aim of the our experiment was to compare the ability of intrastriatal implants of embryonic dopaminergic neurons to reverse two kinds of postlesion modification in the host brain: the change in the activity level of neurons in the denervated area and morphological modifications, e.g. collateral sprouting. The ascending dopaminergic system of 3-day-old rat pups was unilaterally lesioned by an intrahypothalamic injection of the neurotoxin 6-hydroxydopamine. This lesion has been described previously to induce an increase in the level of activity of striatal enkephalinergic neurons. The same lesion leads also to sprouting of the serotoninergic afferents in the striatum, leading to hyperinnervation of this structure. The existence of these modifications thus offers the possibility of testing the influence of grafts in one structure of the same animal on two lesion-induced reactions of different nature. A cell suspension obtained from mesencephali of embryonic day 14 rats and containing dopaminergic neurons was implanted into the denervated striatum of lesioned animals 5 days after the lesion. Nine months later the animals were killed and immunohistochemistry was performed on striatal sections using antibodies directed against tyrosine hydroxylase, methionine enkephalin and serotonin. Intensity of immunostaining (methionine enkephalin and serotonin) as well as innervation density (serotonin) was quantified through the use of a computer-assisted image analyser. The lesion led to the disappearance of striatal dopaminergic innervation. Implanted dopaminergic neurons were found scattered in the striatum and restored a dopaminergic innervation in a large portion of this structure. There was a marked increase in striatal methionine enkephalin immunostaining in lesioned animals, which was most pronounced in the dorsolateral part of the striatum (+ 150% compared to control values), while in the ventral part it was slight or non-existent. The density of striatal serotoninergic innervation was also increased by approximately 250% relative to control values. In grafted animals striatal enkephalin immunostaining was similar to that observed in control animals. On the other hand, the serotoninergic hyperinnervation was still present in the graft-bearing striata. These results suggest that while intrastriatal implants of embryonic dopaminergic neurons are able to counteract modifications in the functioning of local striatal neuronal systems such as the increase in enkephalinergic activity or receptor hypersensitivity occurring as a result of the lesion, they might be unable to reverse postlesion morphological modifications.

Normal distribution of alpha-1-adrenoceptors in the rat spinal cord and its modification after noradrenergic denervation: a quantitative autoradiographic study

The distribution of alpha 1 (alpha 1)-adrenoceptors along the different segments of the spinal cord (cervical, thoracic, lumbar, and sacral) of normal rats has been studied by quantitative autoradiography using the specific alpha 1-antagonist [3H]Prazosin as a ligand. In addition, the influence of noradrenergic (NA) denervation [obtained either by complete transection of the spinal cord at vertebrae level T8-T9 or by selective lesion of NA spinal cord system carried out by intracisternal injection of 6-hydroxydopamine (6-OHDA)] on eventual variations of alpha 1-adrenoceptor density at spinal cord target cells was studied in parallel. In control rats, the quantitative analysis of alpha 1-adrenoceptor densities revealed a widespread distribution of these receptors along all segments of the spinal cord with a similar pattern in the various subregions of gray matter studied. This distribution of alpha 1-adrenoceptors was quite well correlated with the distribution of NA terminals, when referring to previous descriptions by immunohistochemistry. After 6-OHDA lesion, as well as caudally to the transection, a significant increase of alpha 1-adrenoceptor densities was observed in all spinal subregions thus evidencing supersensitivity. These results suggest that NA may act in the spinal cord, at least partly, via alpha 1-adrenoceptors and that the expression of these receptors could be influenced by NA dysfunction, as demonstrated here through the effects observed in lesioned animals.

Up-regulation of dopamine receptors in the brain of the spontaneously hypertensive rat: an autoradiographic analysis

Recent evidence points to a dysfunction of brain dopaminergic mechanisms in the spontaneously hypertensive rat. Using in vitro receptor autoradiography, we assessed the density of D1 and D2 dopamine receptors in the brain of spontaneously hypertensive rats and their normotensive controls the Wistar-Kyoto rat. Brain sections from five- and 15-week-old rats were incubated with 1 nM [3H]SCH 23390 (D1 receptor antagonist) or 15 nM [3H]sulpiride (D2 receptor antagonist), and exposed along with radioactive standards to 3H-Hyperfilm. The binding density of selected brain regions (anteromedial prefrontal cortex, cingulate cortex, lateral septal nucleus, nucleus accumbens, caudate-putamen, globus pallidus, amygdaloid complex) were quantified using computer-assisted densitometry. These experiments showed a significant increase in the binding density of [3H]SCH 23390 in the nucleus accumbens and caudate-putamen of five- and 15-week-old spontaneously hypertensive rats. The binding density of [3H]SCH 23390 was increased in the lateral septal nucleus of five-week-old and globus pallidus of 15-week-old spontaneously hypertensive rats. The binding density of [3H]sulpiride was also greater in the nucleus accumbens of five-week-old spontaneously hypertensive rats. The present investigation demonstrates an up-regulation of D1 dopamine receptors in spontaneously hypertensive rats with established hypertension. More importantly, up-regulation of D1 and D2 dopamine receptors in the striatum of young prehypertensive spontaneously hypertensive rats suggests that dopamine may be involved in the pathogenesis of hypertension in this strain of genetically hypertensive rats.

Ultrastructure of spared dopamine terminals in caudate-putamen nuclei of adult rats neonatally treated with intranigral 6-hydroxydopamine

Residual dopamine terminals in the dorsal striatum, caudate-putamen nuclei (CPN), of adult rats neonatally lesioned with 6-hydroxydopamine (6-OHDA) sustain a relatively high level of dopamine release. We examined whether there were morphological differences in the spared dopamine terminals that might correlate with this increased efficacy. Postnatal male rat pups from 50 litters were pretreated with desmethylimipramine (DMI) to protect from non-specific monoamine damage, then given unilateral intranigral injections of 6-OHDA or vehicle. Coronal sections through the CPN and substantia nigra of the surviving adult animals from each litter were co-processed for immunoautoradiographic or immunoperoxidase localization of the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH). Quantitative ultrastructural analysis established that in animals showing maximal (greater than 90%) depletions in immunoautoradiographic labeling for TH, the number of TH-labeled axons in the CPN ipsilateral to the 6-OHDA injections was reduced to one third of the number seen in the contralateral, unlesioned hemisphere, or the CPN from vehicle-injected animals. The ultrastructural features of residual terminals ipsilateral to 6-OHDA lesions were morphologically similar to those of the contralateral side or in vehicle-injected animals. However, in comparison with controls, these TH-labeled terminals had significantly larger mean cross-sectional diameters. When subdivided into groups according to size, there were significantly fewer small (0.0-0.1 micron 2) and more large (0.41-0.50 micron 2) TH-immunoreactive profiles in lesioned versus unlesioned CPN. The remaining TH-labeled terminals ipsilateral to the 6-OHDA lesions also appeared to be more often in direct contact with unlabeled soma and proximal dendrites as opposed to dendritic spines in the unlesioned CPN. These results suggest that the enhanced activity of dopamine neurons innervating the CPN after nigral 6-OHDA lesions may contribute to changes in size and target of their terminals. Alternatively, the observed large size of remaining dopamine terminals may reflect selective vulnerability of smaller axons to 6-OHDA toxicity.

Is the vulnerability of neurons in the substantia nigra of patients with Parkinson's disease related to their neuromelanin content?

The contribution of neuromelanin (NM) to the pathogenesis of Parkinson's disease (PD) has long been suspected. In particular, a correlation has been reported between the estimated cell loss in the mesencephalic dopaminergic cell groups and the percentage of NM-pigmented neurons in these cell groups. To test whether the amount of pigment per cell is a critical factor or whether the presence of NM within a neuron is sufficient to account for the degeneration of dopaminergic neurons, the NM content was measured in each neuron from representative sections throughout the ventral mesencephalon of four controls subjects and four patients with PD. Intraneuronal NM was quantified by a densitometric method, using known amounts of synthetic melanin as standards. In control brains, the distribution of melanized neurons in the nigral complex showed a high proportion of lightly melanized neurons in the ventral tegmental area and the pars alpha and gamma of the substantia nigra (SN), whereas heavily melanized neurons were mostly located in the pars beta and lateralis of the SN. An inverse relationship was observed between the percentage of surviving neurons in PD compared with controls and the amount of NM they contain, suggesting that the vulnerability of the dopaminergic neurons is related to their NM content. Factors other than NM may be involved in the differential vulnerability of catecholaminergic neurons in PD. In particular, the constant topography of the cell loss suggests that cell position within the nigral complex is a key factor.

Quantitative light microscopic demonstration of increased pallidal and striatal met5-enkephalin-like immunoreactivity in rats following chronic treatment with haloperidol but not with clozapine: implications for the pathogenesis of neuroleptic-induced movement disorders

Acute and late onset movement disorders frequently complicate the treatment of psychosis with typical neuroleptic drugs like haloperidol, but not with atypical neuroleptic drugs like clozapine. Although the neural mechanisms underlying neuroleptic-induced movement disorders remain unknown, alterations in basal ganglia function are likely involved. A potential role for the endogenous opiate peptides in neuroleptic-induced movement disorders is suggested by the immunocytochemical localization of met5-enkephalin (ME) in the striatopallidal projection pathway, and by the increased levels of ME measured by radioimmunoassay in the rat caudate-putamen nuclei (CPN) following haloperidol treatment. We sought to determine whether met5-enkephalin-like immunoreactivity (MELI) in terminal fields within globus pallidus and in perikarya in CPN was differentially altered in rats chronically treated with haloperidol or clozapine. Acrolein-fixed forebrain sections were collected from cohorts of adult rats receiving 21-day oral administration of haloperidol, clozapine, or water. Sections from the three treatment groups were collectively processed for immunocytochemical labeling using varying dilutions of ME antiserum and the avidin-biotin peroxidase method. In globus pallidus, densitometry measures revealed significantly increased levels of immunoperoxidase labeling for ME in haloperidol-treated, but not in clozapine-treated animals. In CPN, optical densitometry as well as cell counting measurements also showed a significant increase in MELI only in the haloperidol-treated group. These results support the concept that alterations in endogenous opiate peptides in basal ganglia may contribute to movement disorders seen in patients receiving typical neuroleptic drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoradiographic localization of dopamine uptake sites in the rat brain with3H-GBR 12935

The regional distribution of dopamine (DA) uptake sites in the rat brain has been studied by quantitative autoradiography using [3H]GBR 12935 as a ligand. The binding of [3H]GBR 12935 to striatal sections was saturable and of high affinity (Kd = 1.6 nM); it occurred at a single population of sites and possessed the pharmacological features of the DA uptake sites. The highest densities of [3H]GBR 12935 binding sites were found in the caudate-putamen, nucleus accumbens, olfactory tubercle, ventral tegmental area and substantia nigra (especially in the pars compacta). Moderate levels of [3H]GBR 12935 binding were observed in globus pallidus, thalamus, hypothalamus, hippocampus, amygdala (basolateral nucleus) and prefrontal and singular cortices. This regional distribution of [3H]GBR 12935 binding closely correlated with the reported distribution of dopaminergic nerve terminals. The topographical distribution of [3H]GBR 12935 has also been studied in detail in striatal subregions and this distribution was compared, using quantitative TH immunoreactivity, to the density of striatal dopaminergic nerve terminals. There is good overlapping between these two regional distributions, the highest density of both markers was found in the lateral part of the striatum and a similar rostro-caudal gradient has been observed. A dopaminergic denervation caused a complete loss of [3H]GBR 12935 in basal ganglia ipsilateral to the lesion.

Increase of striatal methionin enkephalin content following lesion of the nigrostriatal dopaminergic pathway in adult rats and reversal following the implantation of embryonic dopaminergic neurons: a quantitative immunohistochemical analysis

The aim of the present study was to test whether intrastriatal implants of embryonic dopaminergic neurons are able to normalize the lesion-induced dysfunction of striatal enkephalinergic neurons, one of the major output systems of the striatum. The ascending dopaminergic pathway of adult rats was unilaterally lesioned. Three weeks later a cell suspension obtained from the mesencephali of ED14 rat embryos was implanted into the denervated striatum and striatal methionin enkephalin immunostaining was quantified six months later by the use of an image analyser. Methionin enkephalin immunostaining was unevenly distributed in the striatum of control animals. Besides the classical patch/matrix pattern, a mediolateral gradient was also present and, moreover, immunostaining decreased towards caudal levels. Seven months after the lesion of the nigrostriatal dopaminergic pathway, methionin enkephalin immunostaining was found to be increased in the denervated striatum by about 50%. However, relative increases were more sustained in the areas where basal methionin enkephalin immunostaining were lowest, i.e. the lateral striatum and posterior striatal areas. This resulted in an attenuation of the global gradients seen in the normal striatum. Increased immunostaining was also found in the ipsilateral globus pallidus. The implantation, into the denervated striatum, of embryonic dopaminergic neurons led to a reversal of the lesion-induced increase of striatal and pallidal methionin enkephalin immunostaining six months later. Moreover, this reversal resulted in an overshoot, as the level of immunostaining in the graft-bearing striatum was found to be lower than the levels found in the normal striatum. It is concluded that grafts of embryonic dopaminergic neurons can normalize the function of one of the major output systems of the striatum and, through it, influence more distant targets of this structure. This suggests a physiological basis for the behavioral effects observed previously with such grafts.