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T C Rainbow

Publications and source records attributed to T C Rainbow.

At least 37 records · Page 2Linked to original sources
PubMed1984

Localization and characterization by quantitative autoradiography of [125I]LSD binding sites in rat brain.

The binding of [125I]LSD in rat brain was characterized and localized by quantitative autoradiography. Frozen 32 microns thick brain sections were labeled in vitro with [125I]LSD and exposed for 24 h against LKB Ultrofilm to generate autoradiograms. Nonspecific binding was defined as the labelling in the presence of 1 microM D-LSD. Scatchard analysis by densitometry indicated that the binding of [125I]LSD was saturable, with a Kd of 0.2 nM. In agreement with the results of Hartig and co-workers [5,6], [125I]LSD showed a high affinity for 5-HT2 serotonin receptors with some overlap with D-2 dopamine receptors. High concentrations of [125I]LSD sites were observed in layer IV of the cerebral cortex, caudate-putamen, claustrum, olfactory tubercle, nucleus accumbens, ependyma, mammillary nucleus and inferior olive. Co-incubation of sections with sulpiride to block binding to D-2 receptors resulted in a uniform 20-30% reduction in the amount of specific [125I]LSD binding, with no qualitative difference in the pattern of labeling. However, co-incubation with ketanserin to block 5-HT2 receptors resulted in a pattern of binding that was similar to previous descriptions of the location of D-2 receptors, with high levels of residual binding in caudate-putamen, olfactory tubercle, nucleus accumbens and inferior olive. Our results indicate that [125I]LSD is a suitable ligand for quantitative autoradiography of both 5-HT2 and D-2 receptors, and that there is a strong anatomical correspondence between these receptor subtypes, perhaps implying a functional interaction.

Animals↗
PubMed1984

Quantitative autoradiography of binding sites for [3H]AMPA, a structural analogue of glutamic acid.

Binding sites for the potent glutamate agonist [3H] alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) were localized in rat brain frozen sections by quantitative autoradiography. Highest levels of binding were seen in stratum radiatum and stratum oriens of the CA1 hippocampal subfield and in the dorsal subiculum. Substantially less but still high amounts of [3H]AMPA binding occurred in other hippocampal subfields and in rostral forebrain structures. The heterogeneous nature of [3H]AMPA binding is discussed in relation to [3H]glutamate binding visualized by similar methods. From these data it is suggested that [3H]AMPA may label a particular subclass of the glutamate receptor population which exhibits a high affinity for quisqualic acid.

Animals↗
PubMed1984

Localization of cysteine sulfinic acid uptake sites in rat brain by quantitative autoradiography.

In vitro autoradiography was employed to localize and quantify Na-dependent binding sites of [35S]cysteic acid (CA), an analog of cysteine sulfinic acid (CSA). The heterogeneous anatomical distribution and pharmacological specificity of [35S]CA differs from that of the glutamate/aspartate marker D-[3H]aspartate, and appears to represent a specific uptake site for CSA. These results suggest that CSA may act as an excitatory transmitter in the central nervous system.

Amino Acids, Sulfur↗
PubMed1984

Quantitative receptor autoradiography with tritium-labeled ligands: comparison of biochemical and densitometric measurements.

Tritium-labeled receptor ligands are commonly used for quantitative receptor autoradiography with LKB Ultrofilm. In this study, we compared estimates of tritium concentrations by optical density measurements with direct measurements of tritium concentrations by scintillation counting. We found that predominantly grey matter regions of rat brain showed similar tritium concentrations when measured by either method, but that optical density reading of white matter regions indicated a lower tritium concentration than determined by direct measurement with scintillation counting. We also compared measurements of receptor density by quantitative autoradiography with radioligand-binding measurements on microdissected brain regions. Higher per milligram protein levels of muscarinic receptors were obtained by quantitative autoradiography, comparable to the specific activity of receptors found in purified membranes.

Animals↗
PubMed1984

The effect of the beta-adrenergic receptor antagonist, propranolol, on the cerebral spread of a memory trace in mice.

Bi-temporal injections of puromycin that primarily affect the hippocampal-entorhinal areas consistently induce amnesia of aversive maze-learning in mice for 3 days after training but are consistently ineffective if given 6 or more days after training. At these later times, additional puromycin sites covering widespread areas of the forebrain are necessary to induce amnesia. Consistent with other evidence, these observations are interpreted to indicate that the locus of the memory trace becomes more widespread during the 6-day period. A single subcutaneous injection of (-)-propranolol (50 micrograms/kg) given either before or 2 days after training suppressed engram spread for 60-90 days, at which time engram spread spontaneously occurred. This effect of propranolol was stereospecific. Suppression of engram spread persisted for a prolonged period in spite of the rapid recovery (about 4 hr), following treatment, of the normal level of specific binding of 3H-dihydroalprenolol in membrane preparations of the cerebral hemispheres and of 125I-pindolol in selected areas of the forebrain, diencephalon and brainstem.

Animals↗
PubMed1984

Quantitative autoradiography of beta 1- and beta 2-adrenergic receptors in rat brain.

We have used quantitative autoradiography to localize in rat brain beta 1- and beta 2-adrenergic receptors. These receptors were labeled in vitro with 125I-labeled pindolol, an antagonist of beta-adrenergic receptors that binds nonselectively to both beta 1 and beta 2 subtypes. The selective inhibition of 125I-labeled pindolol binding with specific antagonists of beta 1 and beta 2 receptors allowed the visualization of beta-adrenergic receptor subtypes. High levels of beta 1 receptors were observed in the cingulate cortex, layers I and II of the cerebral cortex, the hippocampus, the Islands of Calleja, and the gelatinosus, mediodorsal, and ventral nuclei of the thalamus. High levels of beta 2 receptors were found in the molecular layer of the cerebellum, over pia mater, and in the central, paraventricular, and caudal lateral posterior thalamic nuclei. Approximately equal levels of beta 1 and beta 2 receptors occurred in the substantia nigra, the olfactory tubercle, layer IV of the cerebral cortex, the medial preoptic nucleus, and all nuclei of the medulla. The pronounced differences in the ratio of beta 1 to beta 2 receptors among brain regions suggests that the subtypes of beta-adrenergic receptors may play different roles in neuronal function.

Animals↗
PubMed1984

Progesterone-like effects of estradiol on reproductive behavior and hypothalamic progestin receptors in the female rat.

During the rat estrous cycle, estradiol (E2) and progesterone (P) synergize to activate reproductive behavior. However, receptivity and proceptivity can be elicited by E2 alone in ovariectomized (OVX) animals, particularly when E2 doses are high. The purpose of this study was to determine the neuroendocrine mechanism by which E2 elicits P-dependent reproductive behavior. Adult OVX females received estrogen treatment for 72 h, which consisted of 5 mm Silastic capsules containing 100% E2 or 10% E2, or of 3 injections of estradiol benzoate (EB; 20 micrograms daily). At 72 h, animals were sacrificed for nuclear progestin receptor (NPR) measurements, while others were tested for reproductive behavior. The remaining animals received 1-mg injections of E2, P, moxestrol (Mox) or oil, and either were sacrificed 2 h later for NPR measurements or were tested 4 h later for reproductive behavior. A subset of the animals receiving 1 mg E2 received concurrent administration of the protein synthesis inhibitor, anisomycin (ANI; 100 mg/kg). Acute administration of 1 mg of E2 or P significantly elevated proceptivity, receptivity and NPRs in the mediobasal hypothalamus-preoptic area (MBH-POA) and pituitary (PIT) in females primed with 100% E2. An equivalent dose of Mox was without effect. ANI blocked the acute activation of feminine reproductive behavior by 1 mg of E2. In the absence of acute steroid administration, animals primed for 72 h with EB showed higher levels of reproductive behavior than animals primed with 100% E2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

In vitro biochemical characterization and autoradiographic distribution of 3H-thyrotropin-releasing hormone binding sites in rat brain sections.

In the present study, we describe the biochemical characteristics and the autoradiographic distribution of thyrotropin-releasing hormone (TRH) receptors in the rat central nervous system (CNS) after in vitro incubation of brain slices with 3H-TRH. Scatchard analysis showed that, in the range of concentrations tested (0.7-35 nM), 3H-TRH bound to a single-class of receptors with a dissociation constant of 6 nM and a number of binding sites of 20 fmol/mg protein. Increasing concentrations of unlabeled TRH produced a dose-dependent inhibition of 3H-TRH binding. The only analogue as potent as TRH to displace 3H-TRH binding was 3-Me-TRH, whereas 1-Me-TRH or TRH-free acid as well as pGlu-His, pGlu-Pro-NH2 or His-Pro-diketopiperazine were ineffective. Neither Luteinizing hormone-releasing hormone (LHRH), neurotensin, somatostatin, D-Ala-Met-enkephalin nor VIP showed any significant affinity for TRH binding sites. Autoradiograms obtained by apposition of LKB 3H-Ultrofilm showed that the highest concentrations of 3H-TRH binding sites were found in the ventral dentate gyrus of the hippocampal formation, the lateral amygdaloid nucleus, the nucleus accumbens, and the thalamic paraventricular nucleus. The biochemical characterization of 3H-TRH binding in brain sections is in good agreement with previous reports on membrane preparations and the autoradiographic localization of the binding sites provides anatomical support for the effects of TRH in the CNS.

Amygdala↗
PubMed1984

Correlation of muscarinic receptor induction in the ventromedial hypothalamic nucleus with the activation of feminine sexual behavior by estradiol.

The administration of the steroid hormone, 17 beta-estradiol (E2) to ovariectomized rats increases the levels of muscarinic cholinergic receptors by 20-40% in the hypothalamic area. Using microdissection techniques, this increase has been shown to occur in hypothalamic subregions that possess high levels of intracellular receptors for E2. Among these regions is the ventromedial nucleus (VMN), which may be the principal target site in the rat brain for the activation of feminine sexual behavior by E2. In this study, we have further characterized the increase in muscarinic binding within the VMN after E2 and show that it satisfies many of the criteria for an important regulatory mechanism by which E2 could activate sexual behavior: (1) Using quantitative receptor autoradiography, it was determined that the increase in [3H]-QNB binding in the VMN after E2 results from an increase in the number of receptors rather than a change in the affinity of the binding. (2) The increase in VMN muscarinic receptors as determined by the binding of [3H]-QNB to microdissected homogenates occurred by 18-24 h after exposure to E2, the earliest time at which sexual behavior is facilitated. (3) Increased muscarinic receptors did not occur in the VMN of male rats, which show little activation of feminine sexual behavior after E2 exposure. (4) Muscarinic receptors in the VMN of female rats are induced at 24 h by a 6 h exposure to E2, the minimum length of time that is sufficient for E2 to activate sexual behavior. A 4 h exposure to E2 is insufficient to activate both sexual behavior and induce muscarinic receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Organizational effects of testosterone via aromatization on feminine reproductive behavior and neural progestin receptors in rat brain.

The present studies were undertaken to determine whether estrogenic actions of testosterone during development govern the apparently irreversible suppression of feminine reproductive behavior in the male and lead to a suppression of the capacity of the ventromedial nucleus (VMN) of the hypothalamus to produce cytosol progestin receptors (CPRs) in response to estrogen priming. Timed-pregnant female rats received daily injections of the aromatase inhibitor 1,4,6-androstatriene-3,17-dione (ATD; 5 mg/0.2 ml) from the 14th day of pregnancy until parturition. Males exposed to ATD in utero received Silastic capsules containing ATD for the first 10 days of life. Some females from litters not exposed to ATD received injections of estradiol benzoate (EB; 10 micrograms) 6-12 h and 3 days after birth. The remaining pups not exposed to ATD served as controls. Pups were gonadectomized on days 60-70 and were tested for feminine reproductive behavior or killed for CPR measurements on days 85-90. To elicit behavior, animals received daily injections of EB (15 micrograms for 3 days) and one injection of progesterone (500 micrograms) 4 h before testing. To induce CPRs, animals received EB but not progesterone. Significantly less receptive and proceptive behavior was observed in males and females given perinatal EB than in normal females and males given perinatal ATD. The CPR content of the VMN in males was similar to that in females given perinatal EB and significantly less than that in normal females and males given perinatal ATD. Neonatal hormonal manipulation did not alter the CPR content of other hypothalamic or preoptic nuclei. These findings are consistent with the hypothesis that one event mediated by estradiol which underlies activation of feminine reproductive behavior is the induction of CPRs in the VMN. This capacity is apparently restricted by estrogen-mediated events in males during the perinatal period.

Androstatrienes↗
PubMed1984

Localization of L-glutamate receptors in rat brain by quantitative autoradiography.

In vitro autoradiography was used to characterize and quantitatively map the sodium-independent binding of [3H]glutamate in rat brain. Measured in the presence of chloride, glutamate binding to frozen brain sections was specific, saturable, and reversible, with a Kd in the low micromolar range. At least two distinct binding sites were detected which had different affinities for quisqualic acid (0.7 microM and 1.2 mM). Autoradiograms revealed very high levels of binding in rostral forebrain areas, especially olfactory structures and frontal cortex. High levels of binding were found in sensory cortex, certain hippocampal subfields, caudate, lateral septum, and other limbic structures. Lowest levels were seen in globus pallidus, preoptic area, brainstem reticular formation, and spinal trigeminal nucleus. All other regions, including midbrain, thalamus, hypothalamus, and cerebellar cortex exhibited moderate levels of [3H]glutamate binding. Within the hippocampus glutamate binding was greatest in the inner two-thirds of the dentate molecular layer, subiculum, and CA1 stratum radiatum. CA3 was much less densely labeled; CA2 and CA4 were intermediate. Unlike cell layers in the cerebellum, hippocampal pyramidal and granule cell layers appeared mostly devoid of binding. The relationship of these binding sites to putative glutamate receptor subclasses and glutamatergic pathways is discussed.

Animals↗
PubMed1984

Do vasopressin-related peptides induce hippocampal corticosterone receptors? Implications for aging.

The aged rat shows a decline in hippocampal corticosterone receptors and dysfunction in learning and adrenocortical physiology previously linked to glucocorticoid effects upon the hippocampus. The Brattleboro rat, congenitally lacking vasopressin, also has a low number of hippocampal glucocorticoid receptors, as well as learning and endocrine impairments similar to those seen in the aged. Centrally acting vasopressin analogues correct the receptor loss in the hippocampus in the Brattleboro rat but do not influence the hippocampal receptor deficit in the aged rat. Quantitative and high resolution autoradiographic procedures were utilized to characterize the glucocorticoid receptor deficit in the aged and Brattleboro rats. Quantitative autoradiography showed that in both aged and Brattleboro subjects, losses in receptors were most extreme in the pyramidal layer of the CA3a region. High resolution autoradiography revealed striking differences in the cellular basis of the receptor losses. Brattleboro rats had decreased binding of [3H]corticosterone per neuron, whereas aged subjects, in addition, had significant losses in the number of corticosterone-concentrating neurons. Taken together, our findings indicate that the glucocorticoid receptor deficit in the Brattleboro rat probably represents a vasopressin-influenced defect in the synthesis or degradation of the receptor, whereas in the aged rat the deficit originates from loss of both receptor per neuron and the steroid-concentrating neurons themselves, and thus is most likely a permanent and pharmacologically insensitive deficit.

Aging↗
PubMed1983

Quantitative autoradiography of [3H]prazosin binding sites in rat forebrain.

We have used the LKB Ultrofilm method of autoradiography to localize and quantify in rat forebrain the binding sites for [3H]prazosin, a highly-selective antagonist for the alpha 1 adrenoreceptor subtype. Frozen 32 microns thick brain sections were labeled in vitro with 1 nM [3H]prazosin and applied against LKB Ultrofilm for 60 days to generate autoradiograms. Non-specific binding was defined as the labeling in the presence of 10 microM phentolamine. The highest levels of prazosin binding were found in layer V of the motor portion of the frontoparietal cortex and in all nuclei of the thalamus. Moderate levels of alpha 1 receptors were observed in the remaining layers of the cerebral cortex and in most regions of the limbic system. Low levels of prazosin binding occurred in the caudate-putamen and the accumbens nucleus. Our results indicate that alpha 1 adrenoceptors are distributed heterogeneously throughout the rat forebrain.

Animals↗
PubMed1983

Quantitative autoradiography of [3H]corticosterone receptors in rat brain.

We have quantified corticosterone receptors in rat brain by optical density measurements of tritium-film autoradiograms. Rats were injected i.v. with 500 microCi [3H]corticosterone to label brain receptors. Frozen sections of brain were cut with a cryostat and exposed for 2 months against tritium-sensitive sheet film (LKB Ultrofilm). Tritium standards were used to convert optical density readings into molar concentrations of receptor. High levels of corticosterone receptors were present throughout the pyramidal and granule cell layers of the hippocampus. Moderate levels of receptors were found in the neuropil of the hippocampus, the lateral septum, the cortical nucleus of the amygdala and the entorhinal cortex. All other brain regions had low levels of receptors. These results extend previous non-quantitative autoradiographic studies of corticosterone receptors and provide a general procedure for the quantitative autoradiography of steroid hormone receptors in brain tissue.

Amygdala↗
PubMed1983

Distribution of imipramine binding sites in the rat brain studied by quantitative autoradiography.

The distribution of imipramine binding sites in rat brain was examined by the LKB film method of autoradiography. Brain sections were labeled in vitro with [3H]imipramine in the presence or absence of 100 microM unlabeled desmethylimipramine to define non-specific binding. The binding of [3H]imipramine to brain sections was saturable, specific and of a high affinity (2-6 nM). There were very high levels of imipramine binding sites in the dorsal and medial raphe nuclei and over the superficial layers of the superior colliculus. Moderately high concentrations were observed in the olfactory tubercule, interpeduncular nucleus and substantia nigra, among others. There were low levels of binding sites over white matter and in the ventral thalamus. The distribution of imipramine binding sites parallels the distribution of serotonin terminals in rat brain. These results are consistent with the hypothesis that the high affinity imipramine binding site is associated with the presynaptic uptake site for serotonin.

Animals↗