Changes in the dynamic state of brain proenkephalin-derived peptides during amygdaloid kindling

The dynamic state of the proenkephalin (PE) gene products during and after development of amygdaloid kindling was assayed by monitoring changes of the accumulation of PE mRNA and changes in proenkephalin-related peptides. A parallel determination of PE mRNA and peptides from the same sample was conducted in this study. Electrical stimulation of the amygdala causes early increases in the PE mRNA content in that structure and in the hippocampus. Other areas related with the amygdaloid complex do not exhibit such an early increase, but this alteration occurs when the kindling process is fully established. Enkephalin content increases early in amygdala and hippocampus presumably owing to an increase in synthesis rate. Also, the enkephalin content of areas connected with amygdala and hippocampus such as the entorhinal cortex, the nucleus accumbens, and the frontal and occipital cortex exhibits an increase. A clear tendency towards normalization is observed after a recovery period of 2-3 months. Rekindling of the animals after this recovery period does not elicit a similar pattern of changes in the dynamic state of enkephalin system, even though the animals rekindle with just one single stimulation. The present data suggest that the enkephalinergic neurons participate in the development and spreading of kindling phenomena after amygdaloid stimulation, but they do not seem to play any role in mediating maintenance of the kindling state.     

Potential of [(18)F]beta-CFT-FE (2beta-carbomethoxy-3beta-(4-fluorophenyl)-8-(2-[(18)F]fluoroethyl)nortropane) as a dopamine transporter ligand: A PET study in the conscious monkey brain

A dopamine transporter (DAT) ligand 2beta-carbomethoxy-3beta-(4-fluoro-phenyl)-8-(2-[(18)F]fluoroethyl)nortropane ([(18)F]beta-CFT-FE) was synthesized and evaluated in comparison with [(11)C]beta-CFT in monkey brain using animal positron emission tomography (PET). [(18)F]beta-CFT-FE and [(11)C]beta-CFT were injected intravenously to conscious monkeys for a 91-min PET scan with arterial blood sampling for metabolite analysis. In the conscious state, [(18)F]beta-CFT-FE provided a peak about 20 min after the injection and declined thereafter in the striatum of monkey brain, while [(11)C]beta-CFT continuously increased with time up to 91 min after injection. Metabolite analysis revealed that [(18)F]beta-CFT-FE was more rapidly metabolized in plasma than [(11)C]beta-CFT. The striatal binding of both ligands was dose-dependently displaced by preadministration of a specific DAT inhibitor, GBR12909, at doses of 0.5 and 5 mg/kg; however, the displacement degree of [(11)C]beta-CFT-FE was higher than that of [(18)F]beta-CFT. The effects of the anesthetics, ketamine and isoflurane, on binding were more prominent in [(11)C]beta-CFT than [(18)F]beta-CFT-FE. Specificity and affinity of beta-CFT-FE to DAT were evaluated in an in vitro assay using cloned human DAT, serotonin transporter, and norepinephrine transporter in comparison with other conventional DAT ligands, showing that beta-CFT-FE had lower affinity and higher specificity to DAT than beta-CFT and beta-CIT. These results suggested that [(18)F]beta-CFT-FE could be a potential imaging agent for DAT, providing excellent selectivity and tracer kinetics for quantitative PET imaging.     

Ketamine alters the availability of striatal dopamine transporter as measured by [(11)C]beta-CFT and [(11)C]beta-CIT-FE in the monkey brain.

The effects of ketamine anesthesia on the binding of [(11)C]-labeled cocaine analogs, [(11)C]beta-CFT (2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane) and [(11)C]beta-CIT-FE (N-(2-fluoroethyl)-2beta-carbomethoxy-3beta-(4-iodophenyl)tropane), to the striatal dopamine transporter (DAT) were evaluated in the monkey brain using positron emission tomography (PET). We sequentially measured the kinetics of these labeled compounds in the brains of five young-adult male rhesus monkeys (Macaca mulatta) in the conscious state, followed by those under ketamine anesthesia with continuous infusion (3 and 10 mg/kg/h). After intravenous injection, [(11)C]beta-CFT and [(11)C]beta-CIT-FE were predominantly accumulated in the striatum in both conscious and ketamine-anesthetized states. In the conscious state, the striatal uptake of [(11)C]beta-CFT and [(11)C]beta-CIT-FE continuously increased with time up to 91 min after injection. Continuous infusion of ketamine-induced higher levels of uptake of [(11)C]beta-CFT and [(11)C]beta-CIT-FE into the brain in a dose-dependent manner as compared with conscious state, and kinetic analysis with metabolite-corrected arterial input function indicated that the binding potentials (BP = k(3)/k(4)) of both compounds were elevated by ketamine. Not only [(11)C]beta-CIT-FE but also [(11)C]beta-CFT reached the equilibrium state of specific binding in the striatum within 40-50 min after injection. The present results demonstrated that ketamine significantly alters the DAT availability as measured with [(11)C]beta-CFT and [(11)C]beta-CIT-FE in the brain.     

Distribution of β-lipotropin (β-LPH), adrenocorticotropin (ACTH) and α-melanocyte-stimulating hormone (α-MSH) in the rat brain. I. Origin of the extrahypothalamic fibers

By immunocytochemical techniques, the neuronal cell bodies containing ACTH, β-LPH and α-MSH have only been found in the area of the arcuate nucleus of the hypothalamus, whereas positive nerve fibers have been observed in many hypothalamic and extra-hypothalamic areas. The possible contribution of neurons which could be located in other brain areas has been studied in the rat by experiments involving hypothalamic deafferentation or destruction of the acurate nucleus. Fourteen days after deafferentation, no immunoreactive fibers could be detected in extrahypothalamic areas whereas the concentration of positive cell bodies and fibers remained unchanged within the hypothalamic island. In rats which had been injected in the neonatal period with monosodium glutamate (MSG), which selectively destroys the arcuate nucleus, only a few immunostained cell bodies were observed in hypothalamic region lateral to the arcuate nucleus. As compared to control animals, the concentration of immunostained fibers in both hypothalamic and extrahypothalamic regions was markedly decreased. These results strongly suggest that neuronal cell bodies producing ACTH, β-LPH and α-MSH are located in the region of the arcuate nucleus and send axonal projections into many brain areas.     

Colocalization of [H]muscimol and antisera to GABA and glutamic acid decar☐ylase within the same neurons in monkey retina

Two procedures have been used to test for the colocalization of different neuroanatomical γ-aminobutyric acid (GABA)ergic markers within the same neurons in primate retina. First, sequential immunocytochemical processing of sections was done using antisera to glutamic acid decar☐ylase and to GABA, and these antisera were visualized by peroxidase-antiperoxidase and fluorescein isothiocyanate techniques respectively. Colocalization of both antisera was found within the same neuron cell bodies. In the second experiment, immunocytochemical staining using GABA antiserum was performed on retinal tissue that had been previously incubated in vitro for neuronal uptake of [³H]muscimol. Both markers colocalized in 70% of the labeled cell body population.     

Presence of a reduced opioid response in interleukin-6 knock out mice

Cytokines are known to influence neuronal functions. The purpose of this study was to investigate the putative role of the cytokine interleukin-6 (IL-6) in the pathways involved in opioid-mediated responses, by using IL-6-deficient mice. We reported that with a thermal stimulus IL-6-knock-out (IL-6KO) mice presented nociceptive thresholds similar to those measured in their controls. However, they showed a reduced analgesic response both to the restraint stress and to the administration of low doses of morphine. Hypothalamic levels of the opioid peptide beta-endorphin were significantly higher in IL-6KO mice than they were in their controls. The development of tolerance to the analgesic effect of morphine was more rapid in IL-6-deficient mice than in wild-type controls. Binding experiments showed that the number of opioid receptors in the midbrain, but not in the hypothalamus, decreased in IL-6KO mice. Autoradiographic binding analysis revealed that the density of mu receptors diminished while the delta-opioid receptors did not. These results suggest that IL-6 is necessary for a correct development of neuronal mechanisms involved in the response to both endogenous and exogenous opiates.     

Interaction of beta-funaltrexamine with [3H]cycloFOXY binding in rat brain: further evidence that beta-FNA alkylates the opioid receptor complex.

beta-Funaltrexamine (beta-FNA) is an alkylating derivative of naltrexone. In addition to acting as an irreversible inhibitor of mu-receptor-mediated physiological effects, intracerebroventricular (i.c.v.) administration of beta-FNA to rat attenuates the ability of selective delta receptor antagonists and naloxone to reverse delta receptor-mediated effects. Moreover, recent work demonstrated that i.c.v. administration of beta-FNA alters the conformation of the opioid receptor complex, as inferred by a decrease in the Bmax of the lower affinity [3H][D-ala2,D-leu5]enkephalin binding site. Consistent with the decreased potency of naloxone as an inhibitor of delta receptor mediated effects, beta-FNA doubled the naloxone IC50 for displacing [3H][D-ala2,D-leu5]enkephalin from its lower affinity binding site. These data collectively support the hypothesis that the opioid receptor complex postulated to mediate mu-delta interactions in vivo is identical to the opioid receptor complex as defined by vitro ligand binding studies. A direct prediction of this hypothesis is that beta-FNA should increase the Kd of antagonists for the mu binding site (mu cx) of the receptor complex. The data reported in this paper demonstrate that beta-FNA doubled the IC50 of the potent narcotic antagonist, 6-desoxy-6 beta-fluoronaltrexone (cycloFOXY) for displacing [3H][D-ala2,D-leu5]enkephalin from its lower affinity binding site, and doubled the Kd of [3H]cycloFOXY for its mu binding site, providing additional data that the mu binding site labeled by [3H]cycloFOXY is the mu binding site of the opioid receptor complex. beta-FNA also altered the kappa binding site labeled by [3H]cycloFOXY, and when administered intrathecally to mice, beta-FNA produced a longlasting antinociception in the acetic acid writhing test.     

Topographical distribution of pro-opiomelanocortin-derived peptides (ACTH/β-END/α-MSH) in the rat median eminence

The detailed distribution of adrenocorticotropin (ACTH), beta-endorphin (beta-END) and alpha-melanotropin (alpha-MSH) immunoreactivity was examined in the rat median eminence (ME) and pituitary stalk using light microscopic immunocytochemistry and radioimmunoassay (RIA). Nerve fibers and varicosities immunoreactive for ACTH/beta-END/alpha-MSH had identical distributions in the ME suggesting that they are part of the same arcuate proopiomelanocortin neuronal (POMC) system. The quantitative image analysis of POMC immunoreactive varicosities in the ME indicates no significant differences between the various rostro-caudal segments. In the main (preinfundibular) portion of the ME, a moderate density of immunoreactive elements was located in the lateral part of the internal zone and throughout the postinfundibular ME. Very few scattered varicosities were observed in the neurohemal (external) zone and in the pituitary stalk. By RIA, alpha-MSH is present in a substantially higher concentration than ACTH and beta-END throughout the ME. Knife cuts between the arcuate nucleus and ME indicate that proopiomelanocortin (POMC) fibers enter the ME in its whole rostro-caudal extent. Thus POMC neurons seem to provide innervation of structures in the internal zone but not in the neurohemal/external/zone where the portal capillary system is located. Moreover, the observation that the density of immunoreactive elements is substantially lower in the pituitary stalk than in the ME, suggests that the majority of immunoreactive fibers in the internal zone are not fibers of passage directed towards the neurohypophysis.     

Specific activation of the mu opioid receptor (MOR) by endomorphin 1 and endomorphin 2

The recently discovered endomorphin 1 (Tyr-Pro-Trp-Phe-NH2) and endomorphin 2 (Tyr-Pro-Phe-Phe-NH2) were investigated with respect to their direct receptor-binding properties, and to their ability to activate G proteins and to inhibit adenylyl cyclase in both cellular and animal models. Both tetrapeptides activated G proteins and inhibited adenylyl cyclase activity in membrane preparations from cells stably expressing the mu opioid receptor, an effect reversed by the mu receptor antagonist CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2), but they had no influence on cells stably expressing the delta opioid receptor. To further establish the selectivity of these peptides for the mu opioid receptor, brain preparations of mice lacking the mu opioid receptor gene were used to study their binding and signalling properties. Endomorphin 2, tritiated by a dehalotritiation method resulting in a specific radioactivity of 1.98 TBq/mmol (53.4 Ci/mmol), labelled the brain membranes of wild-type mice with a Kd value of 1.77 nM and a Bmax of 63.33 fmol/mg protein. In membranes of mice lacking the mu receptor gene, no binding was observed, and both endomorphins failed to stimulate [35S]guanosine-5'-O-(3-thio)triphosphate ([35S]GTPgammaS) binding and to inhibit adenylyl cyclase. These data show that endomorphins are capable of activating G proteins and inhibiting adenylyl cyclase activity, and all these effects are mediated by the mu opioid receptors.     

Beta-endorphin/ACTH immunocytochemistry in the CNS of the lizard Anolis carolinensis: evidence for a major mesencephalic cell group

The immunocytochemical distribution of beta-endorphin and other proopiomelanocortin (POMC) peptides in the central nervous system of the lizard Anolis carolinensis was determined. Colchicine pretreatment was used to enhance perikaryal immunoreactivity. A major finding of this study is the localization of a previously undetected mesencephalic cell group which exhibits immunoreactivity to beta-endorphin, ACTH, and alpha-MSH. The perikarya of these neurons are large, bipolar, and situated in the mesencephalic tegmental area. They appear to project to the mesencephalic central gray and other brainstem structures. In contrast, the immunoreactive parvicellular perikarya of the medial-basal hypothalamus, corresponding to the POMC perikarya of the rodent arcuate nucleus, exhibit major rostral projections to various telencephalic and diencephalic structures. The exact extent of fiber projections and innervation patterns arising from either of these two groups is not clear at this time and will require further analyses. Scattered fiber immunoreactivity was also seen in the medial cerebral cortex and the striatal complex, regions which apparently are not innervated by beta-endorphin fibers in the rodent brain. Also, no immunoreactivity was seen to an antiserum to the 16K peptide of POMC. Other similarities and differences in the brain distribution of POMC in reptiles and mammals are discussed.     

Opioid peptide receptor studies. 17. Attenuation of chronic morphine effects after antisense oligodeoxynucleotide knock-down of RGS9 protein in cells expressing the cloned Mu opioid receptor

RGS proteins are a recently described class of regulators that influence G-protein-mediated signaling pathways. We have shown previously that chronic morphine results in functional uncoupling of the mu opioid receptor from its G protein in CHO cells expressing cloned human mu opioid receptors. In the present study, we examined the effects of morphine treatment (1 microM, 20 h) on DAMGO-stimulated high-affinity [35S]GTP-gamma-S binding and DAMGO-mediated inhibition of forskolin-stimulated cAMP accumulation in HN9.10 cells stably expressing the cloned rat mu opioid receptor, in the absence and presence of the RGS9 protein knock-down condition (confirmed by Western blot analysis). RGS9 protein expression was reduced by blocking its mRNA with an antisense oligodeoxynucleotide (AS-114). Binding surface analysis resolved two [35S]GTP-gamma-S binding sites (high affinity and low affinity sites). In sense-treated control cells, DAMGO-stimulated [35S]GTP-gamma-S binding by increasing the B(max) of the high-affinity site. In sense-treated morphine-treated cells, DAMGO-stimulated [35S]GTP-gamma-S binding by decreasing the high-affinity Kd without changing the B(max). AS-114 significantly inhibited chronic morphine-induced upregulation of adenylate cyclase activity and partially reversed chronic morphine effects as measured by DAMGO-stimulated [35S]GTP-gamma-S binding. Morphine treatment increased the EC50 (6.2-fold) for DAMGO-mediated inhibition of forskolin-stimulated cAMP activity in control cells but not in cells treated with AS-114 to knock-down RGS9. These results provide additional evidence for involvement of RGS9 protein in modulating opioid signaling, which may contribute to the development of morphine tolerance and dependence.     

Cortical efferents of the entorhinal cortex and the adjacent parahippocampal region in the monkey (Macaca fascicularis)

Entorhinal cortex (EC) relays information from the hippocampus to the cerebral cortex. The origin of this entorhino-cortical pathway was studied semiquantitatively and topographically with the use of 23 retrograde tracer injections in cortical areas of the frontal, temporal, and parietal lobes of the monkey. To assess possible alternative, parallel pathways, the parahippocampal region, comprised of temporal pole (TP), perirhinal (PRC), and posterior parahippocampal cortices (PPH), was included in the study. The majority of the cortical areas receive convergent projections from EC and the parahippocampal region. Strong EC layer V output is directed to temporal pole, medial frontal and orbitofrontal cortices, and the rostral part of the polysensory area of the superior temporal sulcus (sts). Moderate EC output is directed to the caudal superior temporal gyrus, area TE, and parietal cortex, and little to none to the lateral frontal cortex. With the exception of the projection to the medial frontal cortex, output from TP, PRC, and PPH surpassed that from EC, although with regional differences. TP layers II-III, V-VI project strongly to all areas injected except parietal cortex and caudal superior temporal gyrus, while PRC layers III/V-VI send strong projections to rostral parts of area TE and sts. PPH layers III/V-VI project heavily to parietal cortex and caudal superior temporal gyrus. These results suggest that the medial temporal output is primarily organized hierarchically, but at the same time, it has multiple exits of information. These parallel, alternative routes may influence local circuitry in the cerebral cortex and participate in the consolidation of declarative memory.     

Immunohistochemical localization of the pro-opiomelanocortin-gene product, glycylglutamine, in the intermediate pituitary

Glycylglutamine, the car☐yterminal sequence of β-endorphin_1–31, is produced as a free dipeptide during the posttranslational synthesis of β-endorphin_1–27. Antisera which recognize glycylglutamine were raised in rabbits and used for immunohistochemistry. With these antisera, glycylglutamine immunoreactivity was demonstrated in cells of the rat intermediate pituitary. In contrast, anterior pituitary cells, which exhibited β-endorphin immunoreactivity, did not react with the anti-glycylglutamine sera. The conclusion that the antisera distinguished glycylglutamine immunoreactivity from β-endorphin_1–31 immunoreactivity is based upon cellular specificity, fixation requirements and blocking studies. The antisera demonstrated the differential expression of this dipeptide product of the proopiomelanocortin prohormone. The efficacy of carbodiimide as an immunohistochemical fixative for small molecules is also known.     

Activation of the hypothalamo-anterior pituitary corticotropin-releasing hormone,adrenocorticotropin hormone and β-endorphin systems during the estradiol 17β-induced plasma LH surge in the ovariectomized monkey

The present work describes time-dependent changes in the content of corticotropin-releasing hormone (CRH), adrenocorticotropin (ACTH), and β-endorphin (β -EP) in the hypothalamus (HT) and anterior pituitary (AP) and in the concentration of ACTH and β-EP in the plasma during the 17β estradiol (E2) benzoate (E₂B)-induced luteinizing hormone (LH) surge in ovariectomized cynomolgus monkeys. Monkeys were euthanized at 0, 30, 48, 72, and 96 hr post-E₂B. HT and AP were rapidly dissected, extracted in 2 N acetic acid containing 1 mM phenylmethane sulfonyl fluoride at 4°C, and centrifuged at 18,000g for 30 min. Peptide concentrations were measured in the supernatant by specific radioimmunoassays (RIAs). In the HT, there were significant (P < 0.05) decreases in ACTH and β -EP content by 30 hr post-E₂B and a significant (P < 0.05) decrease in HT CRH content 48 hr post-E₂B. Thereafter, CRH, ACTH, and β-EP content increased up to 72 hr post-E₂B. In the AP, there was an almost linear decrease in the CRH content through 48 hr post-E₂B followed by a marked 20-fold (P< 0.01) increase in the AP CRH content at 72 hr post-E₂B, which corresponds to the time of the descending arm of the LH surge. The patterns of ACTH and β-EP content were very similar in the AP, while that of CRH differed markedly. In contrast, in the HT CRH, ACTH, and β-EP profiles were very similar. Significant (P< 0.05) increases in circulating levels of ACTH, β-EP, and cortisol were evident at 30 hr (all 3 hormones), 48 hr (β-EP and cortisol), and 72 hr (cortisol) post-E₂B, which corresponds with the time of decreased hypothalamic content of CR1I, ACTH, and β-EP. These results suggest that there may be a marked activation of the hypothalamo-anterior pituitary-adrenal axis during the negative and positive feedback phases of the E₂B-induced LH surge in the ovariectomized monkey. © 1995 Wiley-Liss, Inc.     

Identification of a second category of α-melanocyte-stimulating hormone (α-MSH) neurons in the rathypothalamus

An immunocytochemical localization of alpha-melanocyte-stimulating hormone (alpha-MSH) as well as ACTH and a fragment (16K) of the common precursor of ACTH and beta-lipotropin (beta-LPH) was performed in rat brain. Two different groups of neuronal cell bodies showing alpha-MSH-like immunoreactivity (alpha-MSH-LI) were observed in the hypothalamus. One group of neurons located in the arcuate nucleus was shown to contain not only alpha-MSH-LI, but also ACTH and the 16K fragment. A second category of alpha-MSH-LI-containing neurons was characterized by the complete absence of staining for ACTH and 16K fragment. These neurons were mainly located in the dorsal-lateral portion of the hypothalamus. Immunoelectron microscopy showed that immunostaining for alpha-MSH was restricted to dense core vesicles in the positive perikarya. Nerve fibers staining for alpha-MSH (but not for ACTH and 16K fragment) were also observed outside the ACTH-beta-LPH pathway, especially in the cortex, caudate-putamen nucleus and hippocampus. These findings strongly suggest the presence of two different neuronal systems reacting with antibodies to alpha-MSH.     

Changes in the immunoreactivities of an opioid peptide leumorphin in the hypothalamus and anterior pituitary during the estrous cycle of the rat and their relation to sexual behavior

Leumorphin, an opioid peptide whose functions are unknown, is found in mammalian brain and pituitary and stimulates lordosis behavior in estrogen-treated female rats. To elucidate the role of leumorphin in the physiological control of female sexual behavior, the levels of immunoreactive (ir) leumorphin as well as ir dynorphin (dynorphin A) were measured in the rat brain and pituitary during the estrous cycle. There was a clear variation of ir leumorphin in the hypothalamus and anterior pituitary during the estrous cycle. The levels of ir leumorphin in the hypothalamus and anterior pituitary on the afternoon of proestrus were significantly higher (P less than 0.01) than those on the afternoons of estrus and metestrus. The rise in the hypothalamic levels of ir leumorphin on the afternoon of proestrus was correlated with the receptivity of lordosis during the estrous cycle. Furthermore, there was a close correlation with ir dynorphin levels. These findings are in agreement with studies demonstrating a common precursor for leumorphin and dynorphin. Ir leumorphin in the hippocampus and neurointermediate pituitary did not change significantly during the estrous cycle. Because the leumorphin antiserum used recognizes rimorphin (dynorphin B) 1.78 times more than porcine leumorphin on a molar basis, high performance-gel permeation chromatography was done on pooled extracts of hypothalamus taken at proestrus and estrus. The peak in the leumorphin-like substance in the activation of sexual behavior is discussed.     

Comparative binding of biotinylated neurotrophins to alpha(2)-macroglobulin family of proteins: relationship between cytokine-binding and neuro-modulatory activities of the macroglobulins

Human alpha(2)-macroglobulin (alpha(2)M), pregnancy zone protein (PZP), rat alpha(1)M and acute-phase rat alpha(2)M belong to the alpha(2)M gene family of proteins, which can react covalently with nucleophilic monoamines to yield monoamine-activated (MA) macroglobulins. The MA forms of human alpha(2)M, PZP and rat alpha(2)M have been demonstrated previously to inhibit various neurotrophin-promoted neuronal activities, whereas MA-alpha(1)M is neurostimulatory and all native macroglobulins are generally inactive. The mechanism of neuromodulation is unknown, but it has been postulated that MA macroglobulins might inhibit neurons via their binding and sequestration of neurotrophins. This study employed a novel biotinylation-Western blot technique to compare the neurotrophin-binding properties of the four macroglobulins, and to correlate their binding activities with their known neuro-modulatory activities. In comparison with their respective native counterparts, human and rat MA-alpha(2)M bound slightly more NGF, but significantly less BDNF or NT-3. Native human alpha(2)M and PZP in general have no neuro-modulatory activity, but native PZP bound significantly more NGF, BDNF or NT-3 than either native alpha(2)M or MA-alpha(2)M, which is neuro-inhibitory. It is known that MA-PZP is neuro-inhibitory, but it fails to bind more NGF, BDNF, or NT-3 than native PZP. MA-alpha(1)M is the only macroglobulin known to stimulate NGF-promoted neurite outgrowth, but it bound NGF with similar affinities as native alpha(1)M and rat alpha(2)M; in addition, it bound significantly less BDNF or NT-3 than native alpha(1)M. All the bindings were non-covalent and appeared specific. In conclusion, PZP and rat macroglobulins are versatile carriers of neurotrophins with diverse binding capacities, and the neurotrophin-binding property does not appear to mediate the neuro-modulatory activity of these human and rat macroglobulins.     

Subchronic haloperidol increases CB(1) receptor binding and G protein coupling in discrete regions of the basal ganglia

The present study was designed to test whether chronic neuroleptic treatment, which is known to alter both expression and density of dopamine D(2) receptors in striatal regions, has effects upon function and binding level of the cannabinoid CB(1) receptor in the basal ganglia by using receptor autoradiography. As predicted, subchronic haloperidol treatment resulted in increased binding of (3)H-raclopride and quinpirole-induced guanosine 5'-O-(gamma-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) in the striatum when compared to that measured in control animals. This increased D(2) receptor binding and function after 3 days washout was normalized after a 2-week washout period. Effect of haloperidol treatment was studied for CB(1) receptor binding and CP55,940-stimulated [(35)S]GTPgammaS in the striatum, globus pallidus, and substantia nigra. (3)[H]CP55,940 binding levels were found in rank order from highest to lowest in substantia nigra > globus pallidus > striatum. Furthermore, subchronic haloperidol treatment resulted in elevated binding levels of (3)[H]CP55,940 in the striatum and the substantia nigra and CB(1) receptor-stimulated [(35)S]GTPgammaS bindings in the substantia nigra after 3 days washout. These increased binding levels were normalized at 1-4 weeks after termination of haloperidol treatment. Haloperidol treatment had no significant effect on CB(1) receptor or [(35)S]GTPgammaS binding levels in globus pallidus. The results help to elucidate the underlying biochemical mechanism of CB(1) receptor supersensitivity after haloperidol treatment.