Immunohistochemical localization of gonadotropin-releasing hormone (GnRH) in the brain and infundibulum of the sheep

Dees, W. Les; Sorensen, A. M.; Kemp, Walter M.; McArthur, N. H.

doi:10.1007/bf00236258

Cited by 18 publications

(26 citation statements)

References 21 publications

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“…However, in addition to populations of singlelabeled OFQ cells in these areas, we found an exceptionally high percentage of GnRH-ir cells that colocalized OFQ. Double-labeled OFQ/GnRH cells were not regionally restricted, and a similar high percentage of colocalization (Ͼ90%) was seen in each brain region in which GnRH cells are found (Table 1), even though the total number of GnRH neurons in each region varied as expected (22,31,32). The high percentage of colocalization suggests that OFQ is functionally important in the control of GnRH secretion.…”

Section: Discussionmentioning

confidence: 65%

Orphanin FQ: Evidence for a Role in the Control of the Reproductive Neuroendocrine System

et al. 2007

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Orphanin FQ (OFQ), also known as nociceptin, is a member of the endogenous opioid peptide family that has been functionally implicated in the control of pain, anxiety, circadian rhythms, and neuroendocrine function. In the reproductive system, endogenous opioid peptides are involved in the steroid feedback control of GnRH pulses and the induction of the GnRH surge. The distribution of OFQ in the preoptic area and hypothalamus overlaps with GnRH, and in vitro evidence suggests that OFQ can inhibit GnRH secretion from hypothalamic fragments. Using the sheep as a model, we examined the potential anatomical colocalization between OFQ and GnRH using dual-label immunocytochemistry. Confocal microscopy revealed that approximately 93% of GnRH neurons, evenly distributed across brain regions, were also immunoreactive for OFQ. In addition, almost all GnRH fibers and terminals in the external zone of the median eminence, the site of neurosecretory release of GnRH, also colocalized OFQ. This high degree of colocalization suggested that OFQ might be functionally important in controlling reproductive endocrine events. O RPHANIN FQ (OFQ), also known as nociceptin, is a member of the family of endogenous opioid peptides, which also includes ␤-endorphin, enkephalins, and dynorphin (1). Whereas sharing some homology with dynorphin, OFQ does not exhibit appreciable binding affinity for classical opioid receptors (1, 2); rather it functions as an endogenous ligand for the opioid receptor like (ORL)-1 receptor (1). OFQ cells are present in the preoptic area, anterior hypothalamus, and arcuate nucleus of the hypothalamus of the rat (3) and human (4). Functionally, OFQ has been implicated in a variety of systems including pain (5), anxiety (6), cardiovascular function (7), food intake (8), circadian rhythms (9), and cognition (10). There is also evidence that OFQ may play a role in neuroendocrine function: intracerebroventricular delivery of OFQ in the rat stimulates GH and prolactin (11, 12) and has been reported to both stimulate (13) and inhibit (14) corticosterone secretion. Sinchak et al. (15) have shown that OFQ delivered into the ventromedial nucleus facilitates lordosis in female rats in a dose-dependent manner. However, there has been relatively little attention to the possible role of OFQ in reproductive neuroendocrine function, specifically in the control of GnRH secretion.GnRH neurons, and their projections to the median eminence, control the secretion of pituitary LH and thus comprise the final common pathway for the neuroendocrine control of reproduction (16). Endogenous opioid peptides are important regulators of the GnRH system, controlling both the preovulatory surge (17) and pulsatile secretion (18) of GnRH. OFQ has been shown to inhibit forskolin-induced GnRH secretion in a dose-dependent manner from rat hypothalamic fragments (19). OFQ cells in the preoptic area and anterior hypothalamus overlap the site of a majority of GnRH perikarya (20 -22). In addition, OFQ fibers and ORL-1 receptors are present in high abund...

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Section: Discussionmentioning

confidence: 65%

Orphanin FQ: Evidence for a Role in the Control of the Reproductive Neuroendocrine System

et al. 2007

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“…Immunocytochemical analysis has revealed that the distribution of LHRH neurons forms a loosely arranged continuum in the diagonal band of Broca, organum vasculosum of the lamina terminalis (OVLT), medial preoptic area (POA), and the rostral-most anterior hypothalamus in the bovine brain [6,7]. A similar distribution of LHRH neurons was reported in the sheep [8,9].…”

Section: Introductionmentioning

confidence: 59%

Luteinizing Hormone-Releasing Hormone Gene Expression in the Bovine Brain: Anatomical Localization and Regulation by Ovarian State1

Weesner

Harms

McArthur

et al. 1993

Biology of Reproduction

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Experiments were conducted to identify neurons in the bovine brain that express the LHRH gene and to determine whether LHRH mRNA levels are influenced by the ovaries. Two groups of postpubertal heifers were utilized: heifers killed during the mid-luteal phase of the estrous cycle (LUTEAL, n = 5) and heifers killed 14-16 wk following ovariectomy (OVX, n = 5). In situ hybridization was performed through use of a 32P-end-labeled deoxyoligonucleotide (59 mer) complementary to the human LHRH mRNA sequence. LHRH-expressing neurons were identified in the diagonal band of Broca, the preoptic area, and the anterior hypothalamus in a manner consistent with immunocytochemical localization. Reduced silver grains, proportional to LHRH mRNA content, were quantified (in pixels, 45x objective) with an image analysis system. Expected serum hormone concentration differences between endocrine states were confirmed by radioimmunoassay for progesterone (LUTEAL > OVX, p < 0.01) and for LH (OVX > LUTEAL, p < 0.01). Compared to the OVX group, LUTEAL heifers had 34% fewer LHRH-expressing neurons (p < 0.05); on the average, these neurons possessed 28% fewer pixels/cell (p < 0.01), indicating fewer copies of LHRH mRNA per cell. When the numbers of pixels in all labeled cells were totalled, LUTEAL animals had 57% fewer pixels (p < 0.05) than did the OVX females--probably reflecting a decrease in LHRH synthetic capacity in the LUTEAL animals. Therefore, during the mid-luteal phase of the bovine estrous cycle, ovarian steroid (i.e., luteal progesterone) suppression of LHRH release (as reflected by serum LH) is coincident with decreased LHRH mRNA in the brain.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…A recent study which utilized the same antiserum for immunocytochemical procedures in the rat also failed to visualize reactive perikarya [17]. However, immunoreactive LHRH containing perikarya have been localized with this antiserum in the horse [11], sheep [12], and cow [10].…”

Section: Discussionmentioning

confidence: 99%

“…Prior to its use in each as say, the antiserum was preabsorbed with I mg BSA/0.1 ml BSA/0.1 ml 1:100 antiserum (12 h, 4°C) in order to remove any anti-BSA activity. Control procedures to verify the LHRH localiz ing reaction were as described previously by Dees et al [ 12].…”

Section: Methodsmentioning

confidence: 99%

“…The primary LHRH rabbit antiserum utilized in the immunocytochemical procedure was generated against LHRH conjugated to bovine serum albumin (BSA) and has been characterized as requir ing the amino acid sequence from His2 to Gly-NH210 of the LHRH molecule for full immunoreactivity [12]. Prior to its use in each as say, the antiserum was preabsorbed with I mg BSA/0.1 ml BSA/0.1 ml 1:100 antiserum (12 h, 4°C) in order to remove any anti-BSA activity.…”

Section: Methodsmentioning

confidence: 99%

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Immunocytochemical Evidence that Suckling Inhibits the Postovariectomy Depletion of Median Eminence Luteinizing Hormone Releasing Hormone

Culler¹,

McArthur²,

Dees³

et al. 1982

Neuroendocrinology

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Suckling has been demonstrated to impair the release of pituitary luteinizing hormone (LH) and to prevent the dramatic increase in plasma LH observed following ovariectomy. In the present study, the effect of suckling (10 pups/animal) for either 1 or 3 weeks on the relative amount of luteinizing hormone releasing hormone (LHRH) present in the hypothalamus and preoptic area of ovariectomized and intact rats was examined using immunocytochemical methodology. Controls consisted of nonlactating animals which were either intact (diestrous) or ovariectomized for 1 or 3 weeks. Brains were removed following transcardial perfusion of phosphate-buffered formalin and Bouin’s fixative. After dehydration, clearing and paraffin embedding, the brains were sectioned and LHRH localized by an indirect immunoperoxidase technique. A positive reaction denoting the presence of immunoreactive LHRH was observed over axons and termini throughout the rostral to caudal extent of the median eminence (ME) and surrounding the organum vasculosum of the lamina terminalis (OVLT) in the preoptic area. Ovariectomy resulted in a progressive decline in the concentration of LHRH within the ME as evidenced by a reduction in the intensity of the staining reaction and in the number of axons over which the reaction was observed. In contrast, brains from ovariectomized rats which had been suckled appeared to have concentrations of LHRH in the ME equal to or greater than that of the diestrous controls. Similarly, the concentration of LHRH In the ME of intact, suckled rats did not differ significantly from that of the diestrous controls. Neither ovariectomy nor suckling produced any observable change in the relative concentration of LHRH located near the OVLT. These data demonstrate that suckling prevents the depletion of LHRH from the ME following ovariectomy and provide evidence for mechanism by which the suckling stimulus may suppress plasma LH.

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Immunohistochemical localization of gonadotropin-releasing hormone (GnRH) in the brain and infundibulum of the sheep

Cited by 18 publications

References 21 publications

Orphanin FQ: Evidence for a Role in the Control of the Reproductive Neuroendocrine System

Orphanin FQ: Evidence for a Role in the Control of the Reproductive Neuroendocrine System

Luteinizing Hormone-Releasing Hormone Gene Expression in the Bovine Brain: Anatomical Localization and Regulation by Ovarian State1

Immunocytochemical Evidence that Suckling Inhibits the Postovariectomy Depletion of Median Eminence Luteinizing Hormone Releasing Hormone

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