Response of Substance P‐Immunoreactive Nerve Fibres in the Anterior Pituitary to Plasma Oestrogen Levels in the Rat

Ma, Dan; Zhao, Chao; Mayhew, T.M.; Ju, Gong

doi:10.1046/j.1365-2826.1997.00636.x

Cited by 12 publications

(10 citation statements)

References 9 publications

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“…Estrogen treatment in other experimental paradigms has also been reported to differentially regulate SP and CGRP. For example, in the anterior pituitary and hypothalamus, estrogen treatment downregulates SP expression but upregulates CGRP expression (Brown et al 1990; Gon et al 1990; O'Halloran et al 1990; Herbison and Theodosis 1992; Ma et al 1997a). While some studies have shown an increase in CGRP in the DRG by estrogen treatment (Gangula et al 2009) it has also been reported that estrogen can reduce CGRP (Yang et al 1998).…”

Section: Discussionmentioning

confidence: 99%

“…In other neural systems, estrogen has been shown to have a negative effect on SP expression. For example, estrogen treatment has been shown to decrease SP levels in the anterior pituitary (Brown et al 1990; O'Halloran et al 1990; Ma et al 1997a). In neurons of the bed nucleus of the stria terminalis, as well as those in the ventromedial nucleus of cycling female rats, SP immunoreactivity is lowest during proestrus, when estrogen levels are high (Micevych et al 1988).…”

Section: Introductionmentioning

confidence: 99%

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Estrogen effects on pain sensitivity and neuropeptide expression in rat sensory neurons

Sarajari

Oblinger

2010

Experimental Neurology

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While a number of chronic pain conditions are much more prevalent in women than men, the role of estrogen in regulating nociception remains unclear. Estrogen receptors (ER) are known to be expressed in various parts of the nociceptive pathway, including in the small-sized primary sensory neurons of the dorsal root ganglion (DRG). This study evaluated the effects of long-term estrogen replacement on pain sensitivity and neuropeptide expression in the DRG of female Sprague Dawley rats. The goal was to evaluate whether estrogen modulates nociceptive neuropeptides in the DRG in a manner consistent with its effects on pain sensitivity. Our results show that long term (28 days) ovariectomy (ovx) of adult rats induces a profound thermal and mechanical hyperalgesia of the hindpaw and tail compared to ovariectomized animals that were continuously estrogen-treated (ovx+E). Significant changes in the expression of two neuropeptides, substance P (SP) and calcitonin gene related peptide (CGRP), were observed using immunocytochemistry and in situ hybridization (ISH) in the small lumbar DRG neurons which contain ER. CGRP and SP were differentially regulated by estrogen, with SP showing a significant downregulation at both the peptide and mRNA level while CGRP and its mRNA were increased in the DRG of estrogen-treated animals. We also evaluated the development of mechanical allodynia after partial sciatic nerve injury and found that both ovx and ovx+E animals developed significant allodynia within a week of the partial nerve injury, which continued for at least one month. The estrogen treated animals showed a partial amelioration of the extent of the allodynia at 2 weeks post injury. Overall, the results suggest that estrogen has significant anti-nociceptive actions that can be directly correlated with changes in expression of two peptides in the small nociceptive ERα expressing neurons of the DRG.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Estrogen effects on pain sensitivity and neuropeptide expression in rat sensory neurons

Sarajari

Oblinger

2010

Experimental Neurology

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“…In the dog, the synapses are found on corticotropes and somatotropes whereas, in the rat, they can be found on every hormone‐secreting cell type (11–13). Moreover, changes in endocrine status by adrenalectomy or ovariectomy in the rat can profoundly increase the density of the nerve fibres in the anterior pituitary (14, 15). Following adrenalectomy, the increase in immunoreactive nerve fibres is a result of active axonal sprouting (16), and the growth cones of the sprouting nerve fibres appear to favour the corticotropes (17).…”

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confidence: 99%

Dual Excitatory and Inhibitory Effects of Stimulation of Intrinsic Innervation of the Anterior Pituitary on Adrenocorticotropic Hormone Release in the Rat

Gao

2004

J Neuroendocrinology

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The gland cells of the mammalian anterior pituitary are innervated by substantial amounts of nerve fibres, and there is evidence that the nerve fibres are functionally active. In the rat, the nerve fibres make typical excitatory synapses with corticotropes. The physiological significance of this synaptic relationship was investigated in the present study. The anterior pituitary of the rat was sliced and stimulated with electrical field in a chamber. The perfusate was continuously collected and immunoradioassayed for adrenocorticotropic hormone (ACTH). When the gland slices were stimulated at a high frequency of 10 Hz, there was a significant inhibition of ACTH secretion. Stimulation at a low frequency of 2 Hz resulted in a quick and transient excitation of ACTH release. The results indicate that stimulation of the nerve fibres in the anterior pituitary has dual excitatory and inhibitory effects on ACTH secretion.

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“…It has been found that adrenalectomy or ovariectomy in the rat induces significant increases in immunoreactive nerve fibres in the anterior pituitary. 19,20 Because the increase in immunoreactive nerve fibres can be due either to an increase in peptide content in pre-existing nerve fibres, so as to render them detectable by immunohistochemistry, or to an actual increase in the number of nerve fibres. GAP-43 immunoreactivity has been studied.…”

Section: Are the Nerve Fibres Functionally Important Or Are They Redumentioning

confidence: 99%

Evidence for Direct Neural Regulation of the Mammalian Anterior Pituitary

1999

Clin Exp Pharma Physio

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1. The mammalian anterior pituitary was not known to be directly regulated by nervous elements until recently. Although it is generally acknowledged that there are a small number of nerve fibres in the anterior pituitary, they are considered to be autonomic in nature and are not directly involved in the regulation of the activities of the gland cells. 2. A growing body of evidence has been accumulated in the past decade, mainly from our laboratory, indicating that the anterior pituitary can be directly regulated by nerve fibres innervating it. The present article reviews the evidence for the hypothesis that there is neural-humoral dual regulation of the mammalian anterior pituitary. 3. Human, macaque monkey, dog and rat anterior pituitaries have been used for immunocytochemical studies at light and electron microscopic levels. Studies of the changes in the nerve fibres in the anterior pituitary following adrenalectomy or ovariectomy have been conducted on rats. The effects of electrical stimulation of the nerve fibres in the anterior pituitary on adrenocorticotropic hormone (ACTH) secretion have also been studied. 4. There are substantial amounts of nerve fibres in the anterior pituitary. They are in close proximity to the gland cells, including forming synapses. The number of nerve terminals are large. Adrenalectomy or ovariectomy induces an active response of the nerve fibres and electrical stimulation of the nerve fibres changes ACTH secretion. 5. It has been concluded that the anterior pituitary can be directly regulated by the innervating nerve fibres.

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Response of Substance P‐Immunoreactive Nerve Fibres in the Anterior Pituitary to Plasma Oestrogen Levels in the Rat

Cited by 12 publications

References 9 publications

Estrogen effects on pain sensitivity and neuropeptide expression in rat sensory neurons

Estrogen effects on pain sensitivity and neuropeptide expression in rat sensory neurons

Dual Excitatory and Inhibitory Effects of Stimulation of Intrinsic Innervation of the Anterior Pituitary on Adrenocorticotropic Hormone Release in the Rat

Evidence for Direct Neural Regulation of the Mammalian Anterior Pituitary

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