Carol Ann Barraclough

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Progesterone (P) amplifies and advances gonadotropin surges when administered to estradiol (E2)-treated ovariectomized rats. While daily rhythmic LH surges continue to occur in E2-treated rats, they are extinguished in E2- and P (E2P)-treated animals 24 h after P treatment. We examined whether this negative feedback effect on P affect catecholamine activity(More)
Previous studies by others suggest that mid- and hindbrain noradrenergic projections to the hypothalamus may be stimulatory or inhibitory to luteinizing hormone releasing hormone (LHRH) release depending upon the steroid environment of the rat. In the present study we reevaluated the effects of electrical stimulation of the locus coeruleus (LC) in(More)
These studies have examined the role of the preoptic-suprachiasmatic area (POA-SC) in brains of cyclic female hamsters in regulating proestrous preovulatory gonadotropin surges. The spontaneous release of LH and FSH which normally occurs on proestrous afternoon was blocked with phenobarbital. Temporal changes in serum LH and FSH were measured in such(More)
In this study we have demonstrated that acute adrenalectomy (1000 hr proestrus) has no effect on the release of LH on proestrous afternoon. However, chronic adrenalectomy results in the loss of some factor responsible for synchronizing the preovulatory LH surge. Since this investigator has shown previously (15) that progesterone can influence the timing of(More)
Studies by others have shown that parenteral administration of antiestrogens blocks the positive feedback effect of estrogen on the luteinizing hormone (LH) surge mechanism. Since all estrogen-accumulating cells could be affected by this treatment, it is difficult to identify the site(s) at which this steroid acts to affect LH surges. In the present study(More)
We have correlated catecholamine [CA; i.e. norepinephrine (NE), dopamine (DA), and epinephrine (E)] turnover rates in discrete hypothalamic nuclei and in the median eminence (ME), with concentration changes in ME LHRH and serum LH, FSH, PRL, estradiol, and progesterone levels at various times during proestrus and diestrous day 1 in 4-day cyclic rats. CA(More)
Temporal changes in tyrosine hydroxylase (TH) mRNA levels in medullary A1 and A2 neurons and locus coeruleus (LC) cells were studied 6, 12 and 24 h following orchidectomy in rats. Brains from intact controls and sham castrated rats also were evaluated at these same time periods. In situ hybridization histochemistry and quantitative image analysis techniques(More)
This study examined the effects of morphine sulfate and naloxone alone or in combination on phasic luteinizing hormone (LH) secretion in estrogen-treated ovariectomized rats. Thereafter, the effects of morphine on initial concentrations, rate constants and rates of turnovers of norepinephrine and dopamine were evaluated in untreated or morphine-injected,(More)
We examined the effect of acute hypotensive hemorrhage on corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) messenger RNAs (mRNAs) in neurons of the rat hypothalamus. Sprague-Dawley male rats were cannulated (femoral artery and vein) and received a 15 ml/kg.3 min hemorrhage on the morning of the fourth day. Time controls received no(More)