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Biomedical subjects

F L Moore

Publications and source records attributed to F L Moore.

At least 73 records · Page 4Linked to original sources
PubMed1986

Arginine vasotocin immunoreactivity in hypothalamic and extrahypothalamic areas of an amphibian brain.

The distribution of arginine vasotocin immunoreactivity (irAVT) was investigated in the brain of male rough-skinned newts (Amphibia: Taricha granulosa) using microdissection and radioimmunoassay techniques. The highest levels of irAVT were observed in the neuroendocrine hypothalamo-hypophysial system. However, detectable quantities of irAVT (greater than 0.40 ng/mg protein) also were observed in extrahypothalamic areas such as pallium, amygdala, striatum and thalamic, tectal and brainstem nuclei. No irAVT was detected in the olfactory bulb, rostral telencephalon, or in specific areas of the caudal telencephalon and diencephalon. These results indicate that, in amphibians, AVT is distributed among a wide range of brain areas and that there is regional specificity in irAVT concentrations.

Animals↗
PubMed1985

Stress-induced inhibition of reproduction: evidence of suppressed secretion of LH-RH in an amphibian.

Male rough-skinned newts (Taricha granulosa) were used to investigate the hormonal responses associated with stress-induced inhibition of reproduction. When male newts were confined for 1 hr, using a procedure that previously had elicited physiological stress responses, androgen concentrations decreased in the plasma and immunoreactive (ir) LH-RH concentrations increased in the infundibulum and rostral hypothalamus. Likewise, when male newts were injected with 25 micrograms of corticosterone, androgen concentrations decreased and hypothalamic irLH-RH concentrations increased. These data, which are from experiments in February, support the hypothesis that in this amphibian, exposure to acute stress or to exogenous corticosterone can suppress plasma androgen titers by inhibiting the release of LH-RH from the hypothalamus. The effects of the confinement procedure and the injection of corticosterone on the concentrations of irLH-RH and androgens were different for newts in September than for newts in February.

Androgens↗
PubMed1985

Seasonal changes in luteinizing hormone-releasing hormone concentrations in microdissected brain regions of male rough-skinned newts (Taricha granulosa).

Luteinizing hormone-releasing hormone (LHRH) concentrations were measured in specific brain areas of male rough-skinned newts collected from a single population throughout the reproductive cycle. Plasma androgen and corticosterone (B) concentrations were also measured. Androgen concentrations were highest during the breeding season (winter) and lowest during the summer. In contrast, plasma B was lowest during the breeding season and highest in the summer. Concentrations of LHRH in the infundibulum (I) and rostral hypothalamus (RH) were positively correlated throughout the reproductive cycle; LHRH was always higher in the I than in the RH. Concentrations of LHRH in the ventral preoptic area (POA) fluctuated independently of concentrations of LHRH in the I and RH. However, LHRH concentrations decreased to undetectable levels in all three brain areas in March and April, which was before the end of the breeding season and before plasma androgen concentrations had decreased. An injection of LHRH into postbreeding males resulted in a significant increase in plasma androgen concentrations, indicating that the pituitary-gonad axis was still functional at the end of the breeding season. These results support the hypothesis that an abrupt decline in LHRH secretion is the initial endocrine event that signals the end of the breeding season in this amphibian.

Androgens↗
PubMed1985

Luteinizing hormone-releasing hormone facilitates the display of sexual behavior in male voles (Microtus canicaudus).

To investigate whether luteinizing hormone-releasing hormone (LHRH) influences the sexual behavior of male gray-tailed voles (Microtus canicaudus), subcutaneous injections of LHRH (500 ng) were given to intact males and to castrated males with different levels of testosterone replacement. Intact voles, as well as castrated voles with Silastic capsules of testosterone propionate, showed significant facilitation of several parameters of masculine sexual behavior 2 hr after LHRH injection, compared to saline controls. Castrated voles without testosterone replacement showed no sexual behavior, even when injected with LHRH. These results support the hypothesis that LHRH regulates sexual behavior in M. canicaudus and that the behavioral response to LHRH is dependent on testosterone. The specific behavioral parameters affected suggest that LHRH changes the arousal component of masculine behavior in voles.

Animals↗
PubMed1984

Corticotropin-releasing factor (CRF) stimulates locomotor activity in intact and hypophysectomized newts (Amphibia).

Locomotor activity of rough-skinned newts (Taricha granulosa) was significantly higher in intact and hypophysectomized males injected intracranially with 100 ng CRF (ovine corticotropin-releasing factor) than in those injected with 10 ng CRF or saline. In addition, an injection of corticosterone or dexamethasone failed to stimulate newt locomotor activity. These results provide evidence that CRF can act independently of pituitary hormones to stimulate locomotor activity in a nonmammalian vertebrate.

Animals↗
PubMed1984

Stress-induced inhibition of sexual behavior: corticosterone inhibits courtship behaviors of a male amphibian (Taricha granulosa).

When male rough-skinned newts (Taricha granulosa) are exposed to presumptive stressors, the incidence of courtship decreases and plasma corticosterone concentration increases. When sexually active males are injected intraperitoneally with corticosterone (1, 5, 10, 15, 20, or 25 micrograms), the incidence of courtship decreases rapidly and in proportion to the dose of corticosterone. Intracerebroventricular infusion of synthetic corticotropin-releasing factor (CRF) elevates plasma corticosterone levels and suppresses courtship. When male newts receive an injection of metyrapone, a drug that interferes with corticosterone synthesis, the inhibitory effects of stress or CRF infusion on courtship are reduced. These results support the hypothesis that, in this amphibian, elevated levels of corticosterone associated with exposure to stressful stimuli inhibit sexual behaviors.

Adrenocorticotropic Hormone↗
PubMed1983

Contractions of amphibian Wolffian duct in response to acetylcholine, norepinephrine, and arginine vasotocin.

The regulation of sperm transport through the Wolffian duct of male amphibians is poorly understood. These experiments were conducted using rough-skinned newts (Taricha granulosa) to determine if Wolffian ducts are capable of contracting in vitro and, if so, to characterize the contractile responses to acetylcholine (ACh), norepinephrine (NE), and neurohypophysial hormones. Dose-response curves for NE and ACh, which were prepared by measuring isometric contractions, are similar to those reported for mammalian vas deferens. For NE, the minimum effective dose and ED50 were found to be 1 X 10(-5)M and 4.17 X 10(-5)M, respectively. For ACh, the minimum effective dose was 3.2 X 10(-8)M and the ED50 was 1.37 X 10(-5)M. Alpha-adrenoreceptors appear to mediate the contractile responses to NE because phentolamine (10(-5)M) blocked or attenuated the response to NE (10(-6)M, 10(-5)M or 10(-4) M). Beta-adrenoreceptors appear to mediate relaxation because dichloroisoproterenol (10(-5)M) enhanced the response to 10(-5)M NE. The contractile response to three neurohypophysial hormones were also investigated. Arginine vasotocin was more effective in eliciting contractions than oxytocin. The effect of lysine vasopressin was intermediate between arginine vasotocin and oxytocin. These experiments demonstrate that amphibian (Taricha) Wolffian ducts contract in vitro in response to neurotransmitters and neurohypophysial hormones. The contractile response to neurotransmitters occurs in a dose-dependent manner; the response to neurohypophysial hormones is hormone specific.

Acetylcholine↗
PubMed1983

Testosterone-binding protein in a seasonally breeding amphibian.

The concentration of testosterone and dihydrotestosterone (DHT) in the plasma of Taricha granulosa rises markedly during the season when androgen-dependent epigamic structures and behaviors recrudesce. During this season (June-October), the physiological characteristics of the testosterone-binding globulin (TeBG) remain unchanged. Competitive binding studies indicate that TeBG binds fairly specifically to testosterone and DHT. The dissociation constant (5 X 10(-8) M) and binding capacities (ranging from 6 to 12 ng androgen bound/ml plasma) were determined using the charcoal adsorption procedures. Because the binding capacity of TeBG remains unchanged when the concentrations of androgens increase, the proportion of testosterone and DHT bound to TeBG is drastically lower during the breeding season, compared to the nonbreeding season. Furthermore, bilateral castration of male newts apparently reduces the binding capacity of TeBG, but Silastic implants of androgen fail to restore the binding capacity.

Androgens↗
PubMed1982

Luteinizing hormone-releasing hormone involvement in the reproductive behavior of a male amphibian.

The present study demonstrates that an intracerebroventricular injection of luteinizing hormone-releasing hormone (LHRH) activates sexual behaviors and elevates the plasma androgen concentrations in rough-skinned newts (Taricha granulosa). The stimulatory effect of LHRH on male behavior may be a seasonal phenomenon, because LHRH stimulation of sexual behavior was only observed during the early part of the breeding season (November and December). When an active LHRH antagonist was injected into male newts, sexual behavior was suppressed. These studies indicate that endogenous LHRH is involved in regulating sexual behavior in this amphibian.

Animals↗