Helen I'anson

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We tested the hypothesis that hindbrain catecholamine (norepinephrine or epinephrine) neurons, in addition to their essential role in glucoprivic feeding, are responsible for suppressing estrous cycles during chronic glucoprivation. Normally cycling female rats were given bilateral injections of the retrogradely transported ribosomal toxin, saporin,(More)
Growth retardation induced by dietary restriction in the lamb results in a low GnRH pulse frequency, and thus, puberty is delayed. In our experimental model, in which ovariectomized lambs are maintained at weaning weight (approximately 20 kg BW), hypothalamic GnRH is present and releasable, suggesting that central mechanisms limit the release of GnRH during(More)
We investigated whether histaminergic tone contributes to the seasonal catabolic state in Siberian hamsters by determining the effect of ablation of histaminergic neurons on food intake, metabolic rate and body weight. A ribosomal toxin (saporin) conjugated to orexin-B was infused into the ventral tuberomammillary region of the hypothalamus, since most(More)
The genes encoding prokineticin 2 polypeptide (Prok2) and its cognate receptor (Prokr2/Gpcr73l1) are widely expressed in both the suprachiasmatic nucleus and its hypothalamic targets, and this signaling pathway has been implicated in the circadian regulation of behavior and physiology. We have previously observed that the targeted null mutation of Prokr2(More)
In the present study, we determined the involvement of brainstem catecholaminergic inputs to the paraventricular nucleus (PVN) on estrogen receptor alpha (ERalpha) expression in this nucleus during conditions of 48-h fasting, 2-deoxy-d-glucose (2DG)-induced acute glucoprivation and 1-h immobilization, in ovariectomized rats. Our approach was to examine the(More)
Estrogen-dependent enhancement of glucoprivic-induced luteinizing hormone (LH) suppression is hypothesized to be due to increased estrogen receptor alpha (ERalpha)-immunoreactive (ir) cells in specific brain nuclei in a manner similar to fasting. ERalpha expression in various brain areas was determined in ovariectomized rats after systemic 2-deoxy-D-glucose(More)
The present study examined the effect of acute lipoprivation on pulsatile luteinizing hormone (LH) secretion in both normal-fat diet, ad libitum-fed and fasted female rats. To produce an acute lipoprivic condition, mercaptoacetate (MA), an inhibitor of fatty acid oxidation, was administered intraperitoneally to ad libitum-fed or 24-h fasted ovariectomized(More)
Previous research has shown that glucoprivation induced by chronic 2-deoxy-D-glucose (2DG) treatment extends estrous cycle length and disrupts reproductive behaviors in female hamsters, similar to food deprivation. Such treatment also suppresses food intake, which is reversed in male rats by reducing brain histamine levels prior to 2DG treatment. We,(More)
Glutamate and aspartate have been hypothesized to function as neurotransmitters in the regulation of the gonadotropin-releasing hormone (GnRH) neurosecretory system. We, therefore, determined if hypothalamic stimulation of luteinizing hormone (LH) secretion in the intact prepubertal female lamb could be achieved by intravenous injection of(More)
Fasting-induced LH suppression is augmented by estrogen in female rats. We investigated the temporal changes in the number of estrogen receptor alpha (ERalpha)-immunoreactive (ir) cells in various brain regions in ovariectomized rats fasted for 6, 24, 30, and 48 h, commencing at 1300 h. We also determined the anatomical relationship of ERalpha(More)