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F L Moore

Publications and source records attributed to F L Moore.

At least 55 records · Page 3Linked to original sources
PubMed1991

Gonadectomy reduces the concentrations of putative receptors for arginine vasotocin in the brain of an amphibian.

Putative receptors for arginine vasotocin (AVT) in the brain of the newt (Taricha granulosa) were measured using quantitative autoradiography with tritium-labelled vasopressin. Specific binding sites were observed in the olfactory bulb, medial (hippocampal) pallium, dorsal pallium, amygdala para lateralis and tegmental region of the medulla oblongata. In both male and female newts, concentrations of binding sites in the amygdala, but not in the other four areas, were significantly lower in gonadectomized animals than in sham-operated controls. The equilibrium dissociation constants (KdS) were not altered by gonadectomy. Since long-tem castration abolishes the effect of AVT injection on sexual behaviors, these results support the hypothesis that gonadal steroids maintain sexual behaviors in this amphibian by maintaining AVT receptors in the amygdala.

Amygdala↗
PubMed1991

Effects of courtship on brain gonadotropin hormone-releasing hormone and plasma steroid concentrations in a female amphibian (Taricha granulosa).

Courtship-induced changes in plasma steroid and brain gonadotropin-releasing hormone (GnRH) concentrations in Taricha granulosa were determined with respect to changes in female sexual receptivity. Females were sacrificed at several times after courtship initiation. Concentrations of GnRH (determined by RIA) in the anterior telencephalon were high at courtship initiation (females unreceptive), but decreased by sperm transfer (females receptive). Courtship had no affect on GnRH concentrations in any other brain region examined. Furthermore, courted, receptive females had higher plasma levels of estradiol than did uncourted controls, and estradiol levels remained elevated above control levels 24 hr after courtship initiation. Courtship had no influence on plasma progesterone or corticosterone levels. To determine if the observed changes in GnRH concentrations in the telencephalon were localized to the nervus terminalis, courted females and controls were sacrificed after 5, 20, or 60 min of courtship. Nervus terminalis GnRH concentrations were higher in courted females than in uncourted controls. These results may represent the first documentation of a naturally occurring physiological change in the nervus terminalis.

Animals↗
PubMed1991

Corticotropin-releasing factor (CRF) antagonist suppresses stress-induced locomotor activity in an amphibian.

Intracerebroventricular (icv) injections of corticotropin-releasing factor (CRF; 25 ng) given to male rough-skinned newts (Taricha granulosa) stimulated locomotor activity tested in a circular arena starting 35 min after the injection. The CRF receptor antagonist, alpha-helical CRF9-41 (ahCRF; 250 or 500 ng), injected icv concurrently with CRF blocked CRF-induced locomotor activity. In contrast, icv injection of ahCRF had no effect on spontaneous locomotor activity. Other studies examined the effect of ahCRF on the elevated locomotor activity that was observed when the animals were stressed (handled or placed in warm water). The CRF antagonist dose dependently attenuated the response to either handling or warm stress tested 2 hr after drug treatment. We also examined the effect of the alpha 2-adrenergic agonist, clonidine, on spontaneous and CRF-induced locomotor activity. Clonidine injected icv dose dependently suppressed spontaneous locomotor activity but not CRF-induced locomotor activity. These studies support the hypothesis that endogenous CRF is involved in mediating stress-induced locomotor activity and indicate that the effects of CRF on locomotor activity are independent of activation of the alpha 2-adrenergic system.

Animals↗
PubMed1990

Ontogeny of immunoreactive gonadotropin-releasing hormone neuronal systems in amphibians.

The ontogeny of gonadotropin-releasing hormone (GnRH) systems was investigated in 3 anuran amphibians (genus Rana) by means of immunocytochemical (ICC) techniques and antibodies generated against 3 different forms of GnRH. Antisera that recognize primarily chicken II and mammalian GnRHs revealed two anatomically and developmentally distinct GnRH systems. One system, referred to here as the forebrain-spinal cord system, contained GnRH immunoreactive (ir) fibers extending from the rostral diencephalon through the ventromedial brainstem to the spinal cord. Intensity of labeling was robust in the youngest, premetamorphic tadpoles, but decreased with age. GnRH immunolabeling in the hypothalamic-pituitary tract was not detected until late prometamorphosis and increased with age. Development of GnRHir in the hypothalamic-pituitary tract coincided with first appearance of GnRHir in the terminal nerve in R. catesbeiana, but not in R. cascadae or R. aurora, suggesting species differences. Comparisons of results obtained with antisera to different forms of GnRH support the interpretation that the forebrain-spinal cord system, hitherto undescribed in amphibians, develops first and synthesizes a non-mammalian, chicken II-like GnRH, and that the hypothalamic-pituitary system develops later and synthesizes primarily mammalian GnRH. We speculate that the forebrain-spinal cord system may represent a GnRH innervation of frog sympathetic ganglia, and that the two GnRH systems are chemically and embryonically distinct.

Aging↗
PubMed1990

Effects of corticotropin-releasing factor (CRF) and opiates on amphibian locomotion.

Male rough-skinned newts (Taricha granulosa) were used as a model for the study of the neuroendocrine regulation of locomotion. Intracerebroventricular (i.c.v.) injections of nanogram quantities of corticotropin-releasing factor (CRF) dose-dependently increased locomotion as measured in a circular open-field test arena. In other studies animals received intraperitoneal (i.p.) injections of saline or naloxone, a synthetic opioid antagonist, followed by i.c.v. injections of saline or CRF. With 1-min intervals between injections, neither i.p. saline nor naloxone injections modified the stimulatory effects of CRF injections on locomotor activity. In contrast, with 20-min intervals between injections, the naloxone-plus-CRF injected newts displayed more locomotor activity than the saline-plus-CRF injected newts, suggesting that the opioid system modulated the behavioral effects of CRF. An i.p. injection of bremazocine, an opiate kappa-receptor agonist, suppressed spontaneous locomotion but not CRF-induced locomotion. In contrast, an i.p. injection of morphine, an opiate mu-receptor agonist, did not affect spontaneous locomotion but reduced CRF-induced locomotion, indicating further that the opioid system may modulate the behavioral effects of CRF in this amphibian. The present study provides the first evidence that both CRF and opioids may be involved in the regulation of amphibian locomotor activity.

Animals↗
PubMed1990

Autoradiographic localization of putative arginine vasotocin receptors in the kidney of a urodele amphibian.

The distribution and characteristics of putative arginine vasotocin (AVT) receptors in the urodele amphibian kidney were investigated using in vitro quantitative autoradiography. Specific binding sites for [3H]arginine vasopressin (AVP) in the kidney of the rough-skinned newt (Taricha granulosa) were located over the glomeruli. Scatchard analysis showed that, in the range of concentrations tested (0.2 to 22 nM), [3H]AVP bound to a single class of receptors with a dissociation constant of 1.4 nM and a binding site concentration of 36.5 fmol/mg protein. Binding displacement studies showed that both AVT and AVP were potent ligands for newt kidney receptors. Two specific antagonist peptides with anti-vasopressor (V1) activity, but not anti-antidiuretic (V2) activity, in rat tissues were tested as well. Both antagonists effectively displaced [3H]AVP from receptor sites in newt kidney slices, indicating that the binding sites in this amphibian resemble the V1 subtype of mammals in ligand specificity. Localization of AVT receptors over kidney glomeruli and ligand specificity of these sites is consistent with the hypothesis that AVT may cause antidiuresis in urodele amphibians at least in part via a glomerular vasoconstricting action.

Animals↗
PubMed1990

Neuroendocrine, behavioral, and morphological changes associated with the termination of the reproductive period in a natural population of male rough-skinned newts (Taricha granulosa).

Male rough-skinned newts (Taricha granulosa) were collected from the same natural population every second week from early April to mid-June. They were either field-tested for their sexual responsiveness or used to measure the plasma concentrations of androgens and corticosterone, the brain concentrations of immunoreactive (ir) gonadotropin-releasing hormone (GnRH) and arginine vasotocin (AVT), and morphological parameters. During the experimental period, the percentage of sexually responsive males gradually declined from 100 to 4%, concurrent with a decrease of plasma concentrations of androgens, but not corticosterone. Concentrations of irGnRH in two brain regions (medial septum; ventral telencephalon containing the nervus terminalis) did not change significantly during this time. In the infundibulum, irGnRH concentrations increased from the end of May to mid-June, which coincided with an increase in plasma androgen concentrations, a marked increase in testis weights, and a decrease of the proportion of males with spermatozoa in their vas deferens. During this period, no changes in irAVT concentrations in four brain regions (infundibulum; pars distalis of the pituitary; interpeduncular nucleus; cerebrospinal fluid) were detected, but significant changes were observed for irAVT in the dorsal preoptic area that were not correlated with the seasonal changes in behavior. Also, during this period, there were decreases in mean body weight and tail height, and in the proportion of males with smooth skin and dark nuptial pads. These results are discussed in view of our current knowledge of the endocrine mechanisms that regulate sexual behaviors and secondary sex characteristics in male amphibians.

Androgens↗
PubMed1990

Evidence for GABA involvement in stress-induced inhibition of male amphibian sexual behavior.

The behavioral effects of GABA analogs were investigated to determine whether GABAergic neurotransmission is involved in the stress-induced inhibition of masculine sexual behaviors in rough-skinned newts (Taricha granulosa). Injections of bicuculline, a GABA antagonist, stimulated male sexual behaviors in a dose-dependent fashion, and the minimum effective dose was 40-fold less when administered centrally rather than systemically, suggesting a central nervous system site of action. Injections of muscimol, a GABA agonist, suppressed reproductive behaviors in male newts, and this inhibition lasted at least 5 hr and was proportional to the dose of muscimol administered. The inhibitory effects of muscimol on newt sexual behaviors could be reversed by a single 100-microgram ip injection of arginine vasotocin. The inhibitory effects of confinement stress or corticosterone (CS) injections on newt sexual behaviors were blocked by pretreatment of newts with mercaptopropionic acid, a blocker of GABA synthesis. As well, bicuculline prevented the inhibition of sexual behavior induced by CS injection. These results support the conclusion that, in a male amphibian, the GABAergic system is involved in the inhibitory mechanisms regulating sexual behaviors and that CS mediates the stress-induced inhibition of sexual behaviors through the GABAergic system.

Animals↗
PubMed1990

Effects of sodium and temperature on naloxone binding in brain tissues of a urodele amphibian.

1. Partially purified brain membranes obtained from male rough-skinned newts (Taricha granulosa) were used to determine the effects of NaCl and temperature on the specific binding of the opioid receptor antagonist [3H]naloxone. 2. The addition of NaCl to the incubation medium at concentrations up to 400 mM produced a dose-related increase of the specific binding of [3H]naloxone. 3. The addition of other salts to the incubation medium had less pronounced effects: KCl and MgCl2 slightly increased and decreased, respectively, the specific binding of naloxone, and CaCl2 had no effect. 4. Results of an equilibrium saturation experiment showed that the addition of 200 mM NaCl resulted in over a 10-fold increase in the number of high affinity (KD = 0.61 nM) binding sites for naloxone, with no changes in the number of low affinity (KD = 21.8 nM) binding sites. 5. Changes in NaCl concentrations did not significantly affect either dissociation constant. 6. The binding of [3H]naloxone was temperature-dependent; it increased when the incubation temperatures were elevated from 0 degree C to 37 degrees C. 7. Results obtained for this urodele amphibian are compared with those available for other vertebrate species.

Animals↗
PubMed1989

Opiate control of spontaneous locomotor activity in a urodele amphibian.

An intraperitoneal injection of the preferential opiate receptor agonist (+/-) bremazocine HCl given to male rough-skinned newts acutely and dose-dependently reduced their spontaneous locomotor activity. Inversely, and contrary to the situation generally observed in other vertebrates, administration of the opiate receptor antagonist naloxone HCl dose-dependently and acutely stimulated locomotion. Given at a behaviorally active dosage, naloxone counteracted the inhibitory effect of bremazocine on locomotion. The behavioral influence of the two substances was observed using two different sampling techniques (continuous recording for 3 minutes: repeated instantaneous sampling for 60 minutes). These data are discussed in view of our current knowledge on the opiate regulation of locomotor activity in vertebrates.

Animals↗
PubMed1988

Steroidal control of sexual behavior in the rough-skinned newt (Taricha granulosa): effects of testosterone, estradiol, and dihydrotestosterone.

Adult, sexually mature, male rough-skinned newts (Taricha granulosa) obtained from a wild population were castrated and received Silastic capsules containing testosterone (T), estradiol (E), or 5 alpha-dihydrotestosterone (DHT). The newts received three capsules of T, either one or three capsules of E or DHT, or combined treatments with these two steroids. When tested for sexual responsiveness after 32 and 34 days of steroid treatment, no group differed from the castrated controls (C). After 74 and 75 days of treatment, more T-implanted than C newts were sexually responsive, but the newts treated with E, DHT, or these two steroids in combination did not differ behaviorally from the C group. The diameter of the vas deferens was greater in the T- and DHT-treated males than in the C males, indicating that the implants adequately replaced testicular androgens. Together with other studies on this and other species, these results confirm the participation of testosterone in the regulation of sexual behaviors in male amphibians. Furthermore, these results indicate that in this amphibian, the behavioral effects of T are mediated directly by this steroid, not indirectly by enzymatic conversion to DHT or E.

Animals↗
PubMed1988

Brain arginine vasotocin concentrations related to sexual behaviors and hydromineral balance in an amphibian.

Arginine vasotocin (AVT), a potent stimulator of sexual behaviors and regulator of hydromineral balance in male rough-skinned newts (Taricha granulosa), was measured in 11 brain areas using microdissection and radioimmunoassay procedures. A 60-min test for sexual behaviors was used to segregate males into two groups: sexually responsive (initiated amplectic clasping behaviors) and sexually unresponsive (exhibited no sexual behaviors). Compared to sexually unresponsive males, sexually responsive males had significantly higher concentrations of immunoreactive (ir) AVT in the dorsal preoptic area, optic tectum, ventral infundibular nucleus, and cerebrospinal fluid. These results provide evidence for a behavioral action of endogenous AVT in T. granulosa. In another study, irAVT was measured in normal males (control newts maintained in water) and males that were dehydrated for 6 hr. Compared to normal males, dehydrated males had significantly lower concentrations of irAVT in the ventral preoptic area, but not in the other 10 areas of the brain. That different brain areas are associated with sexual behaviors and hydromineral balance suggests that there are some neuroanatomical separations between the behavioral and hydromineral aspects of the vasotocinergic system in this amphibian.

Animals↗
PubMed1988

The nervus terminalis in amphibians: anatomy, chemistry and relationship with the hypothalamic gonadotropin-releasing hormone system.

The nervus terminalis (TN), a component of the olfactory system, is found in most vertebrates. The TN of some fishes and mammals contains neurons immunoreactive (ir) to gonadotropin-releasing hormone (LHRH), and to several other neuropeptides and neurotransmitter systems, but there is little information on TN chemistry in other vertebrate taxa. Using immunocytochemical techniques, we found LHRH-ir neurons in amphibian TNs. In anurans, but not in a urodele, the TN was also found to contain Phe-Met-Arg-Phe-NH2 (FMRFamide) immunoreactivity. LHRH-ir neurons of the TN and those of the septal-hypothalamic system are morphologically homogeneous and form a distinct anatomical continuum in amphibians. Based upon topographical and cytological criteria, we hypothesize that LHRH-ir systems in vertebrates might derive embryonically from the TN.

Animals↗
PubMed1988

Autoradiographic characterization of binding sites labelled with vasopressin in the brain of a urodele amphibian.

Because arginine vasotocin (AVT) activates male sexual behaviors in the rough-skinned newt (Taricha granulosa), quantitative autoradiography with radiolabelled arginine vasopressin (3H-AVP) was used to characterize putative AVT receptors in the telencephalon of this amphibian. Analyses were restricted to specific binding sites in the medial pallium, although dense binding also was observed in the dorsal pallium and amygdala pars lateralis. Binding of 3H-AVP to these sites was saturable, specific, reversible, of high affinity (Kd = 1 nM) and low capacity (57 fmol/mg protein). The rank order of potency of related peptides in inhibiting 3H-AVP binding was as follows: AVT greater than d(CH2)5[Tyr(Me)2]AVP (a mammalian pressor antagonist) greater than AVP, oxytocin, and [dPen1Tyr(Me)2]AVP (also a pressor antagonist) greater than mesotocin much greater than desGly(NH2)AVP, AVP fragment 4-9 and pressinoic acid. Thus, these binding sites appear to represent authentic central nervous system receptors for AVT. Furthermore, ligand specificity for the binding sites in this amphibian differ from that reported for AVP binding sites in rat brains. The AVT receptors in the medial pallium, dorsal pallium, and amygdala pars lateralis may represent site(s) of action where AVT elicits sexual behaviors in male T. granulosa.

Animals↗
PubMed1987

Opioid kappa-receptor agonists suppress sexual behaviors in male rough-skinned newts (Taricha granulosa).

Four experiments were performed to evaluate a possible opioid involvement in the regulation of sexual behavior (amplectic clasping of a female) in intact adult male rough-skinned newts (Taricha granulosa) during the breeding season. It was found that an ip injection of bremazocine, a kappa-receptor opiate agonist, can markedly reduce sexual activity and that an ip injection of naloxone can reverse this inhibition in a dose-dependent fashion. In contrast, in male newts that were sexually inactive before treatment, injections of naloxone failed to induce sexual behavior, suggesting that opioid mechanisms do not normally exert a tonic inhibition of amphibian sexual behavior. In addition, an injection of ethylketocyclazocine (another kappa-receptor agonist), but not morphine (a mu-receptor agonist) suppressed sexual behaviors of male newts. These results indicate that opioid mechanisms that include kappa-type opioid receptors may contribute to the regulation of sexual behavior in nonmammalian vertebrates.

Analgesics↗
PubMed1986

Multiple forms of gonadotropin-releasing hormone in amphibian brains.

Several forms of gonadotropin-releasing hormone (GnRH)-like molecules were found in brains of both anurans (frogs) and urodeles (salamanders). The presence of the mammalian-like GnRH molecule was confirmed by HPLC and cross-reactivity studies. Small amounts of salmonid-like GnRH molecules in the brains of frogs (Rana pipiens, Hyla regilla) and salamanders (Taricha granulosa, Ambystoma gracile) were detected by comparing the HPLC chromatographic pattern and immunological reactivity of the brain extracts with native trout and synthetic salmon GnRH. This nonmammalian form of GnRH in the amphibian brain is similar and perhaps identical, at least by indirect evidence, to a form of GnRH reported earlier to be in sympathetic ganglion, retina, chromaffin tissue, and tadpole brain. If two of the amphibian GnRH molecules prove to be mammalian and salmon GnRH, then it is likely that two separate genes in amphibians code for the distinct primary structures of the molecules. The most parsimonious interpretation of the presence of both mammalian- and salmon-like GnRH in anurans and urodeles is that a common phylogenetic ancestor also possessed the two forms of GnRH. Thus the mammalian form of GnRH may well have been present in labyrinthodont amphibians. Independent of evolutionary origin, the functions of the different GnRH molecules in amphibians are unknown.

Ambystoma↗
PubMed1986

Correlation between immunoreactive vasotocin in optic tectum and seasonal changes in reproductive behaviors of male rough-skinned newts.

Previous studies have shown that intracranial administration of the amphibian neuropeptide arginine vasotocin (AVT) to male rough-skinned newts (Taricha granulosa) can stimulate masculine sexual behaviors. The present study was conducted to determine whether concentrations of endogenous AVT in specific brain areas are correlated with seasonal changes in sexual behavior. Immunoreactive (ir) AVT was measured in the dorsal preoptic area and in the optic tectum throughout the course of the reproductive cycle. In the optic tectum, irAVT levels were low throughout the summer, fall, and winter, but rose over fivefold in the spring when sexual behaviors are most prevalent in male newts. In contrast, irAVT levels in the dorsal preoptic area were high in the summer, but declined in the fall and fluctuated widely during the winter and spring. Thus, there are site-specific changes in irAVT concentrations in the brain of male newts during the seasonal reproductive cycle. The finding that irAVT concentrations in the optic tectum are seasonally correlated with newt sexual behaviors provides further evidence that AVT in this brain area may be important in the expression of sexual behavior.

Animals↗