Search

The present study examined the possible localization of somatosensory orientation in the caudate-putamen (CP) of the rat. In the first experiment, 6-hydroxydopamine (6-OHDA) was injected into either the anterodorsal (AD), anteroventral (AV), posterodorsal (PD), or posteroventral (PV) CP. Only rats with PV-CP 6-OHDA injections showed impaired orientation scores. However, these PV injections often caused widespread CP dopamine (DA) depletions, and no specific CP region appeared to be particularly associated with somatosensory orientation. In the second experiment, multiple injections of 6-OHDA were directed toward the medial or lateral halves of the CP to assess their relative contributions directly. DA depletions confined to the lateral (but not medial) CP resulted in orientation deficits; these deficits were greater than would be predicted from the volume of CP/DA loss. Furthermore, the magnitude of the DA fluorescence loss in the lateral CP was more highly correlated with the orientation impairment than was the medial CP fluorescence loss. Thus the lateral CP contributes to sensorimotor functions to a greater extent than does the medial CP, but the volume of CP/DA depletion also appears important.

The key parameters controlling the productivity and the cost of net high-grade fuel from a system for biomass agriculture and conversion are analyzed. Performance depends sensitively on a "symbiotic" interaction between agronomy and technology. The conditions for obtaining net productivity and costs are explored for U.S. grain alcohol as a reference point. Currently practiced technology consumes more high-grade fuel than it generates. Some potentials and constraints for future systems, including use of other plant species and conversion systems, are explored.

The unilateral injection of 6-hydroxydopamine into the area ventralis tegmenti of rats pretreated with desmethylimipramine resulted in an inattention to somatosensory stimuli impinging on the contralateral body surface. Three separate groups of rats could be identified, that varied in their behavioral deficit: (1) 7 rats showed no recovery of orientation to touch during 4 months postoperatively; (2) 8 showed a marked loss of orientation followed by recovery that was nearly complete within one month; (3) 11 showed a minimal deficit in orientation. Those rats that did recover showed a characteristic pattern: orientation began first to touch of rostral body points (e.g. snout) and only later to touch of caudal body regions. The administration of low doses of alpha-methyl-p-tyrosine or spiroperidol to rats that had spontaneously recovered from their somatosensory loss reinstated their contralateral inattention while not affecting their orientation to ipsilateral touch. As these drugs took effect, orientation was affected first at the caudal body points and only later at more rostral regions. As the drug effects dissipated, orientation was restored rostrocaudally. High correlations were observed between neostriatal DA and the extent of somatosensory orientation observed immediately after surgery (r = +0.76) or during the entire postoperative month (r = +0.66). While the results point clearly to the role of neostriatal DA loss in the somatosensory inattention syndrome, a loss of the DA-containing terminals in olfactory tubercles and nucleus accumbens septi may contribute to this impairment.

Mice homozygous for the autosomal recessive gene weaver (wv) exhibit a regionally specific depletion of forebrain dopamine (DA). DA is reduced approximately 70% in the dorsal striatum of homozygotes (wv/wv) relative to heterozygous (+/wv) controls while DA content in ventral striatum is relatively unchanged. The goal of the present study was to determine the regional effects of the weaver mutation on striatal DA receptors and DA uptake sites using quantitative autoradiography. Catecholamine histofluorescence was used to examine midbrain DA-containing cell bodies. Compared to behaviorally normal (+/-) littermates, the binding of [3H]spiroperidol to D2 sites was significantly increased in the dorsal but not ventral striatum of wv/wv mice. Binding of the D1 ligand, [3H]SCH23390, was significantly decreased throughout the striatum of wv/wv mice. The binding of [3H]mazindol to DA uptake sites was dramatically reduced in all wv/wv striatal regions except the ventrolateral portion. Compared to +/- littermates, wv/wv mice had far fewer fluorescent cell bodies in the substantia nigra and a less pronounced reduction of ventral tegmental area fluorescent somata. These findings support the hypothesis that heterogeneities exist in the genetic control of the mesotelencephalic DA system. The results underscore the usefulness of the weaver mouse in the study of mesostriatal sub-systems, receptor regulation, and potentially as a model of human neuropathologies that affect distinct populations of cells in the mesotelencephalic system.

Unilateral damage to the mesotelencephalic dopamine-containing projection of rats by intracerebral 6-hydroxydopamine injection, alters the staining of the tricarboxylic acid cycle enzyme succinate dehydrogenase in the basal ganglia. Relative to the intact hemisphere, the neostriatum ipsilateral to the damage shows diminished enzyme staining, while the ipsilateral globus pallidus, entopeduncular nucleus and substantia nigra pars reticulata all show enhanced deposition of reaction product. These asymmetries are detectable in some animals by 3 days after surgery and increase in magnitude at longer postoperative survival times. The alterations in succinate dehydrogenase staining appear to be related to the severity of the sensorimotor impairments resulting from the injury.

When placed in a tank of water, aged rats (24 to 27 months old) showed marked impairments in swimming. Compared with young adult rats (3 to 4 months old), the older animals moved their limbs less vigorously and were less successful in keeping their heads above water. The young, but not old, rats maintained a position nearly horizontal to the water surface and planed across it. These movement dysfunctions of aged rats resemble those seen in young adult animals that have sustained injury to brain dopamine-containing neurons. The swimming impairments of the aged rats were reversed by the dopamine receptor stimulant apomorphine and by the biosynthetic precursor of dopamine, L-dopa. Thus, age-related alterations in brain dopaminergic systems may be responsible for some of the movement disturbances associated with senescence.

6-Hydroxydopamine injections along mesostriatal dopaminergic axons can be used to interrupt axonal transport from cell bodies in the substantia nigra pars compacta to terminal fields in the striatum. Such lesions produce accumulations of high-affinity dopamine uptake sites (as measured by [3H]mazindol binding) and acetylcholinesterase proximal to the injection, suggesting that at least a portion of the [3H]mazindol binding and acetylcholinesterase activity seen in the striatum is located presynaptically on the mesostriatal dopaminergic fibers.

Dopamine D2 receptors, labeled with [3H]spiroperidol or [3H]sulpiride, show a lateral-to-medial gradient in the caudate-putamen, with a more than two-fold greater density laterally than medially. It has been thought that D2 receptors are located on at least two neuronal elements of the caudate-putamen, neurons intrinsic to this structure and axons whose cell bodies reside in the cortex. As a first step in establishing what neuronal elements underlie this heterogeneous organization of D2 receptors, we took advantage of quantitative autoradiography to examine the association of these receptors with those elements. The present findings show that the D2 sites are almost exclusively located on neurons whose somata reside in the caudate-putamen and are not located on terminals of corticostriatal axons. A detailed comparison of the distribution of histochemically identified acetylcholinesterase neurons with that of D2 receptors in serially adjoining sections suggests a common organizational pattern. The density of [3H]spiroperidol sites in rat caudate-putamen was determined after unilateral injection of the neurotoxin quinolinic acid into this structure or after ablation of neocortical regions. Quantification of the tissue damage was achieved by acetylcholinesterase histochemistry (following diisopropylfluorophosphate treatment), as well as by thionin and luxol fast staining of sections adjacent to those used for [3H]spiroperidol autoradiography. In identically treated animals, biochemical determination of the extent of tissue damage was made utilizing assays for high-affinity [3H]choline and [3H]glutamate uptake in the caudate-putamen. In quinolinic acid-injected rats, the density of D2 sites was decreased by 90-95% at the site of complete loss of large acetylcholinesterase-positive neurons. Other animals, given ablations of specific neocortical fields (medial prefrontal, motor, somatosensory) or of the entire parietal-frontal cortex of one hemisphere, showed no loss of caudate-putamen D2 sites unless the cortical ablation caused accompanying damage of the caudate-putamen. In the caudate-putamen of all animals there was a close correspondence between the D2 sites and the striatal neurons (and processes) that show strong acetylcholinesterase reactivity. We suggest that the caudate-putamen topography of D2 sites is based largely on the internal organization of this structure and may preferentially involve acetylcholine-containing intrinsic neurons.

Rats in which ascending dopamine-containing neurons have been unilaterally destroyed by injections of 6-hydroxydopamine are known to rotate after being injected with apomorphine or L-dopa. The rotation is markedly reduced by either (i) ipsilateral electrocoagulations of the caudate-putamen or internal capsule or (ii) ipsilateral coronal knife cuts immediately rostral to the substantia nigra. Neostriatal efferent fibers, in particular the strionigral projection, appear to be required for the expression of this dopamine-dependent behavior.

The projections of substantia nigra and ventral tegmental area (SN-VTA) neurons to either the ipsilateral or contralateral caudate-putamen (CP) were studied in intact and 6-hydroxydopamine-treated rats, using both retrograde transport of fluorescent dyes and measurements of dopamine concentration. After unilateral CP injections of nuclear yellow or granular blue in intact 6- or 30-day-old rats, approximately 1% of the retrogradely labeled cells were located in the contralateral SN-VTA. In 6- or 30-day-old rats which had been injected with 6-hydroxydopamine in the left lateral hypothalamic area (LHA) at 1 day of age, the extent of cell labeling of both the uncrossed projection in the right hemisphere and the crossed projection originating in the left SN-VTA was normal. However, the number of labeled cells of the uncrossed pathway of the left side and the crossed pathway originating in the right SN-VTA were markedly decreased by the lesion, indicating that the crossed nigrostriatal cells decussate before they reach the LHA. The 6-hydroxydopamine-induced decreases in SN-VTA labeling of both the crossed and uncrossed pathway closely matched the degree of dopamine depletion in the lesioned CP at 6 days of age and at 30 days of age. A partial recovery of both measures occurred between days 6 and 30. Thus, retrograde labeling of SN-VTA cells and at 30 days of age. A partial recovery of both measures occurred between days 6 and 30. Thus, retrograde labeling of SN-VTA cells with fluorescent dyes provided a quantitative measure of the dopaminergic innervation of the neostriatum in both the uncrossed and crossed pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

Unilateral injections of 6-hydroxydopamine that damaged the mesotelencephalic dopaminergic projection resulted in decreased acetylcholinesterase (AChE) staining in the ipsilateral neostriatum. This reduction, which was most apparent in the posterior and medial anterior neostriatum, occurred in rats killed 3 days or more after the 6-hydroxydopamine injection. No hemispheric asymmetries of AChE staining were found in the medial nucleus accumbens septi, olfactory tubercle or amygdala. Thus, some of the AChE in the neostriatum appears to be localized to its dopaminergic innervation; however, the enzyme may be heterogeneously distributed throughout this structure's dopaminergic afferent fibers. AChE seems not to be associated with dopaminergic axons innervating the limbic forebrain.

Recent investigations of the function of the strionigral pathway have utilized the intranigral injection of gamma-aminobutyric acid (GABA) agonist and antagonist drugs. While the unilateral application of these substances typically produces rotational behavior, the direction of this turning (ipsilateral or contralateral to the injected hemisphere) differs in several reports. The present study determines whether the direction of this drug-induced turning depends upon the locus of migral stimulation. Picrotoxin and bicuculline methiodide were injected into either the pars compacta or the pars reticulata of the substantia nigra at several anterior-posterior levels. Injection of these drugs into the pars compacta resulted in ipsilateral turning while injection into the pars reticulata produced contralateral rotation. Both of these effects were dose-dependent and were elicited by similar threshold doses of picrotoxin. Prior 6-hydroxydopamine treatment abolished the ipsilateral but not the contralateral rotation. In contrast, muscimol injections produced contralateral turning independent of whether they were made into the pars compacta or pars reticulata. However, 6-hydroxydopamine treatment only attenuated the contralateral turning produced by pars compacta injections. These findings provide a histological basis for understanding the different types of turning behavior elicited by the intranigral injection of GABA agonists and antagonists. In addition, they suggest that GABA receptors mediate at least two independent actions in substantia nigra.

Infusion of 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) into the right internal carotid artery of a cynomologus monkey (Macaca fascicularis) induced an almost complete loss of the dopaminergic innervation of the right caudate-putamen and hemiparkinsonism. Digital subtraction autoradiography revealed that at 8 weeks postinjection, a major increase in [3H]spiroperidol binding to D-2 sites in the lateral regions of the right caudate nucleus and putamen occurred, without a significant change in the medial caudate nucleus and putamen. The 92-96% decrease in specific [3H]mazindol binding observed in the right striatum extended into the medial caudate nucleus and putamen and confirmed the extensive loss of dopamine inputs to this structure. The region of the increase in D-2 receptor density is innervated by somatosensory, motor and parietal cortex. This indicates that the increase in D-2 receptor density in this region of the striatum may play a particularly important role in the L-dihydroxyphenylanine-induced motoric recovery observed in such animals.

Alterations in neostriatal dopamine metabolism, release, and biosynthesis were determined 3, 5, or 18 days following partial, unilateral destruction of the rat nigrostriatal dopamine projection. Concentrations of dopamine and each of its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 3-methoxytyramine (3-MT) were markedly decreased in the lesioned striata at 3, 5, or 18 days postoperation. The decline in striatal high-affinity [3H]dopamine uptake closely matched the depletion of dopamine at 3 and 18 days postoperation. However, neither DOPAC, HVA, nor 3-MT concentrations were decreased to as great an extent as dopamine at any time following lesions that depleted the dopamine innervation of the striatum by greater than 80%. In these more severely lesioned animals, dopamine metabolism, estimated from the ratio of DOPAC or HVA to dopamine, was increased two- to four-fold in the injured hemisphere compared with the intact hemisphere. Dopamine release, estimated by the ratio of 3-MT to dopamine, was more increased, by five- to sixfold. Importantly, the HVA/dopamine, DOPAC/dopamine, and 3-MT/dopamine ratios did not differ between 3 and 18 days postlesioning. The rate of in vivo dopamine biosynthesis, as estimated by striatal DOPA accumulation following 3,4-dihydroxyphenylalanine (DOPA) decarboxylase inhibition with NSD 1015, was increased by 2.6- to 2.7-fold in the surviving dopamine terminals but again equally at 3 and 18 days postoperation. Thus, maximal increases in dopamine metabolism, release, and biosynthesis occur rapidly within neostriatal terminals that survive a lesion. This mobilization of dopaminergic function could contribute to the recovery from the behavioral deficits of partial denervation by increasing the availability of dopamine to neostriatal dopamine receptors. However, these presynaptic compensations are not sufficient to account for the protracted (at least 3-week) time course of sensorimotor recovery that has been observed following partial nigrostriatal lesion.

Experiments were conducted to investigate whether chronic dopamine (DA) D2 receptor blockade and DA denervation exert additive effects on striatal D2 receptor density. We employed for the first time chronic treatment with a pure D2 antagonist, metoclopramide, and measured regional striatal DA receptor binding with quantitative receptor autoradiography. Rats with extensive unilateral DA denervation induced by intracerebral 6-hydroxydopamine (6-OHDA) were injected daily for 21 days with either metoclopramide (30 mg/kg i.p.) or saline. Following a 72-h drug wash-out period, rats were sacrificed and brain sections through the caudate-putamen and nucleus accumbens were incubated with [3H]spiroperidol or [3H]SCH 23390 to assay D2 and D1 receptors, respectively. Autoradiographic analysis revealed that chronic metoclopramide treatment increased the density of D2 sites in the intact hemisphere for all regions examined without further augmenting the already increased density of D2 receptors seen in the 6-OHDA-treated hemisphere. In addition, chronic metoclopramide and 6-OHDA treatment by themselves exhibited remarkably parallel anterior-posterior gradients in their effects on D2 receptor density. D1 receptor density was not affected by metoclopramide treatment but was slightly reduced in the DA-denervated hemisphere. [3H]Mazindol labelling of high-affinity DA uptake sites indicated that the extent of DA denervation was greater than 98% in both saline- and metoclopramide-treated rats. These findings are consistent with the view that chronic D2 receptor blockade and DA denervation act via a single, common mechanism to increase D2 receptor density. Work from other laboratories, in which additive effects of denervation and chronic neuroleptic treatment have been purported, may have resulted from incomplete denervation. Experimental discrepancies may also be due to differing means by which the mesotelencephalic dopaminergic neurons are injured.

The regulation of hippocampal muscarinic M1 and M2 receptors was studied by autoradiographic methods following cholinergic denervation and reinnervation from embryonic septal transplant. In young adult male rats the density of M1 sites, labeled either with 3H-pirenzepine (PZ) or 3H-N-methylscopolamine (NMS, in the presence of excess carbachol), exceeded by 4- to 5-fold the density of M2 sites, labeled with 3H-NMS in the presence of excess PZ. Both receptors appeared to be densest in hippocampal regions lowest in acetylcholinesterase or 3H-hemicholinium-3 binding. The distribution of M1 receptors did differ from the distribution of M2 receptors within subregions of the hippocampus. Along the mediolateral axis from the subiculum to the lateral CA 1, the density of M1 receptors is uniform, but the density of M2 receptors decreases. Also apparent is the relatively small difference in density between the CA1 and dentate gyrus for M1 receptors but a significantly greater difference for M2 receptors. However, the response of M1 and M2 receptors to long-term cholinergic denervation following fimbriafornix transection of the septal cholinergic input and to cholinergic innervation by embryonic septal transplants was similar. Long-term denervation (40-60 d) resulted in a 30-60% increase in both M1 and M2 receptors within regions of the hippocampal formation. Receptor levels were reduced to normal in regions innervated by septal transplants. For both receptors, the changes in the density of sites were due to alterations in the Bmax and not the Kd for the radioligands. The specificity of this regulation is supported by the evidence that (1) the degree and topography of the normalization of muscarinic receptor density was entirely dependent on the degree and pattern of cholinergic reinnervation by the fibers of the septal transplant, (2) cholinergic fiber reinnervation by embryonic striatal grafts also down-regulated the density of M1 and M2 receptors, and (3) successfully surviving transplants (e.g., cerebellar and striatal) that did not provide innervation to the hippocampus did not induce down-regulation of muscarinic receptors. Changes in the density of sites were not related to changes in the width of the hippocampus following denervation and reinnervation. The data support the view that the majority of M1 and M2 receptors are located postsynaptically on neurons within the hippocampus and not presynaptically on cholinergic fibers.

Dopamine (D2) receptors visualized in postmortem human striatum by quantitative autoradiography of [3H]spiroperidol binding are organized into circumscribed zones of low receptor density separated from other such zones by regions of higher D2 density. The D2-rich zones of the caudate nucleus and putamen contain twice the binding of D2-poor zones. The Hill coefficient, obtained from saturation analysis of [3H]spiroperidol binding to thin sections of human striatum, gave a value near unity, indicating the binding was occurring to a single type of site. The patchiness of [3H]spiroperidol binding was unaltered by postincubation removal of lipid from the tissue sections, indicating that a differential absorption of tritium in white and grey matter does not account for the heterogeneous distribution. The D2-rich and D2-poor regions appear to form labyrinths oriented in the anterior-posterior axis and are typically aligned with, respectively, acetylcholinesterase-rich and -poor compartments as visualized on stained adjacent sections. Thus, the distribution of dopamine D2 receptors conforms to the "striosomal" organization of the human caudate-putamen, a finding that suggests that this receptor subtype may mediate the influence of dopamine on distinct neurochemical compartments within the structure.

The striatum and olfactory tubercle of 30-month-old F344 rats contain significantly (21-24%) less dopamine compared with young adult (8-month) animals. However, rats of the two age groups show identical Km and Vmax values for the kinetics of [3H]dopamine uptake into striatal homogenates; uptake into the olfactory tubercle also appeared unaffected in old age. The preservation of dopamine uptake despite reductions in content of the transmitter suggests that the forebrain dopaminergic nerve terminals are intact, but that reduced dopamine synthesis and/or enhanced degradation may occur in the existing terminals. Administration to senescent animals of the dopamine uptake blockers nomifensine or bupropion (but not the norepinephrine uptake blocker desmethylimipramine) improved their swim performance to levels comparable with young adult animals. The findings suggest that amine reuptake may limit the synaptic effectiveness of dopamine released in the aged striatum.

Senescent (26-28 months) Fischer 344 rats were shown to have a lower density of D2 sites (-36%) without any change in affinity in membranes prepared from homogenized caudate-putamen (CPU), as compared to young adult (5-6 months) rats. In additional rats prepared for quantitative autoradiography of [3H]spiroperidol binding, the loss was shown to be specific for and quite extensive (50-60%) in the lateral to ventrolateral region of the CPU. The region of the CPU that shows the major age-related loss of D2 sites is critically involved in sensorimotor functions; therefore this regional loss of D2 sites may contribute importantly to the sensorimotor deficits in aged rats.

The potency of chloroaluminum sulfonated phthalocyanine (ClAlSPc) as a photosensitizing agent for photodynamic therapy of cancer was evaluated in vivo by its ability to be taken up and retained by murine tumors of diverse histological origin. Antitumor effects following laser irradiation were evaluated by measurement of the tumor weights of dissected-out tumor masses. Three tumors (Colo 26, a colorectal carcinoma; M5076, a reticulum cell sarcoma; and UV-2237, a fibrosarcoma) growing s.c. in the flank region retained substantially greater quantities of ClAlSPc than did adjacent skin and muscle achieving peak values 24-48 h after the i.v. administration of ClAlSPc (10 mg/kg). The relative magnitude of ClAlSPc retention by these tumors was Colo 26 greater than M5076 greater than UV-2237. However, normal liver and spleen were organs which retained the greatest amounts of ClAlSPc even compared to the s.c. grown tumors and other normal tissues examined. Flow cytometric analysis of tumor cell suspensions obtained from collagenase-digested tumors showed that individual neoplastic cells were capable of taking up and retaining ClAlSPc. Photodynamic therapy, undertaken by i.v. administration of dye (5 mg/kg) followed 24 h later by local laser light irradiation (675 nm, 100 J), brought about significant (Colo 26, M5076, and 3LL tumors) and obvious but nonsignificant (UV-2237 tumor) reductions in tumor weights, as assessed 5 days later. Thus, selective tumor retention of ClAlSPc coupled with a significant response to red light produced dramatic alterations in cancer growth.

Stimulated Raman scattering has been used to convert the output wavelength of a ruby-laser radar (lambda = 6943 A) into the oxygen A band near 7660 A. The system has been used to measure the energy backscattered from the lower atmosphere at both 6943 and 7658 A. Smith and Platt [NOAA Technical Memorandum, NESS 89 (1977)] have shown that such differential-absorption lidar measurements can be used to give both pressure height profiles and vertical temperature profiles. Some correlation between pressure height and oxygen absorption has been found, but greater transmitted energies and better frequency stability at the converted wavelength are required before an operational system can be implemented.

Unilateral lateral hypothalamlic lesions in rats produce deficits in orientation to contralateral visucal, olfactory, whisker-toluch, and somatosetnsory stimuli. This syndrome of sensory neglect appears to be involved in some of the deficits in feedinig and attack which follow bilateral lateral hypothalamic lesions.