Quantification of Naloxone Binding Sites in Brains from Suckled Beef Cows during Postpartum Anestrus and Resumption of Estrous Cycles

Trout, William E.; Malven, P.V.

doi:10.2527/jas1988.664954x

Cited by 12 publications

(7 citation statements)

References 20 publications

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“…The rapid change in ME LHRH content that oc curs with weaning of calves was associated with changes 442 Leshin/ Rund/ Kraeling/Crim/ Kiser Postpartum Differences in ß-END Neurons in opioid peptides in the POA and hypothalamus [26], In vitro LHRH release from ME of postpartum suckled cows was greater from tissue obtained at day 5 than at later times [43]. Finally, suckled anestrous cows had higher concentrations of opioid binding sites in tissue ho mogenates containing the preoptic-anterior hypothal amic regions than suckled cows that reinitiated estrous cycles [21 ]. In a companion study [23], we found in these same cows that LHRH dendritic lengths and ME innervation by LHRH axons and terminals were both reduced in EPP cows compared to CYC cows.…”

Section: Discussionmentioning

confidence: 99%

“…However, naloxone administration enhanced secre tion of LHRH into hypophysial portal vasculature of bull calves [16], sheep [17] and rats [18] presumably by disinhibiting the actions of endogenous opioids on LHRH secretion [19], Two potential sites of action in cows are the preoptic area (POA) and median eminence (ME). In these regions proopiomelanocortin (POMC; p-endorphin producing) neurons are closely associated with LHRH neurons [20], opioid receptors are present [21,22] and naloxone enhances LHRH secretion from both re gions when perifused in vitro [22],…”

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confidence: 99%

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Distribution of β-Endorphin Immunoreactivity in the Arcuate Nucleus and Median Eminence of Postpartum Anestrus and Luteal Phase Cows

La²,

Rr³

et al. 1992

Neuroendocrinology

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Deficiency in the secretion of luteinizing hormone-releasing hormone (LHRH) from the median eminence (ME) is one of the factors limiting reinitiation of estrous cycles following parturition in cows. In previous studies, administration of naloxone, an opioid receptor antagonist, to postpartum cows increased LH secretion, suggesting that endogenous opioids inhibit the secretion of LHRH. This study employs quantitative light microscopy to describe morphological changes in the distribution of immunoreactive β-endorphin (ir-β-END) neurons in the hypothalamus of anestrous early postpartum (EPP, days 10-16, n = 5), midpostpartum (MPP, days 33-43, n = 4) and multiparous cycling cows (CYC, months 12-14, n = 4). Cryostat sections (60 µm) of perfusion-fixed ventral diencephalon and forebrain were immunostained with anti-β-END serum via the biotin-avidin-peroxidase method or double stained sequentially with anti-LHRH serum, then anti-β-END serum. In all cows, β-END immunoreactive perikarya, mostly bipolar neurons, were located in the arcuate and periarcuate nucleus (ARC), with some perikarya in the ME. Within the ARC, the percentage area immunostained for ir-β-END was greater (p < 0.01) for the CYC than EPP cows, with MPP intermediate but not significantly different from the other groups. Consistent for all cows, the percentage area of ir-β-END in ventral ARC regions was greater (p < 0.05) than dorsal ARC regions. Fibers from these neurons coursed into the anterior hypothalamus, preoptic area and bed nucleus of stria terminalis. Ventrally projecting fibers entered the ME forming a densely staining band within the external layer. The percentage area stained was similar among all three postpartum groups. Few (1%) close associations between ir-β-END varicosities and LHRH perikarya and dendrites were found in the anterior hypothalamus and ventral preoptic regions. However, within the external lamina of the ME extensive intermingling of ir-β-END and LHRH varicosities were commonly observed. The reduced area of staining in the ARC of EPP cows compared to CYC cows may reflect an altered activity of β-END neurons during this period.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Distribution of β-Endorphin Immunoreactivity in the Arcuate Nucleus and Median Eminence of Postpartum Anestrus and Luteal Phase Cows

La²,

Rr³

et al. 1992

Neuroendocrinology

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show abstract

“…Indeed, lower values of these parameters were significantly correlated with longer post‐partum anoestrus. Trout and Malven (1988) reported no differences between anoestrous and cyclic suckled cows in either pituitary receptors for GnRH or secretory patterns of plasma LH, but the former had higher tissue concentration of naloxone (an endogenous opioid receptor antagonist) binding sites in the pre‐optic area and the basal forebrain.…”

Section: Discussionmentioning

confidence: 96%

Luteinizing hormone and growth hormone secretion in early lactating Spanish beef cows

Álvarez-Rodríguez

Palacio

Tamanini

et al. 2010

Journal of Animal Physiology and Animal Nutrition

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The episodic release of luteinizing hormone (LH) and growth hormones (GH) was studied in three suckling regimens and two breeds of Spanish suckled cows. Parda de Montaña (PA) cows (n = 21) were assigned to once-daily, twice-daily or ad libitum (ADLIB) suckling. Pirenaica (PI) cows (n = 7) were used to evaluate the breed effect in twice-daily suckling. Coccygeal blood samples were collected twice weekly during lactation to determine the interval from calving to first ovulation through peripheral progesterone. On day 32 ± 3 post-partum, jugular blood samples were drawn at 15 min intervals during 8 h to analyse circulating LH and GH. The interval to first ovulation was greater in PA cows suckling ADLIB than in restricted suckling treatment (RESTR1), whereas in RESTR2 it did not differ from the other two treatments. There were no differences between PA and PI cows in the interval to first ovulation. RESTR1 cows showed a tendency to have shorter LH peak widths than ADLIB cows. PA cows showed a tendency to have longer LH peak widths than their PI counterparts. There were no differences across treatments or breeds in any of the GH measures of secretion. The LH release was more affected by breed than by suckling frequency, whereas that of GH was not influenced by any of these parameters. The variables that best allowed discrimination between ADLIB and restricted nursing systems were the interval to post-partum first ovulation, LH peak number and the mean GH concentration.

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“…Each brain was removed, wrapped in foil and placed on ice. Within 1 h after removal, each brain was prepared for measurement of naloxone binding sites (Trout and Malven, 1988).…”

Section: Methodsmentioning

confidence: 99%

“…Because the results of Exp. 1 did not reveal any differences due to hormone treatment, another study was designed with the following improvements: 1) filtration replaced centrifugation for separation of bound and free [3H]NAL in order to allow smaller fragments of tissue to be assayed, 2) POA and basal forebrain (BF) tissues shown to contain opioid receptors that varied with postpartum reproductive states in cattle (Trout and Malven, 1988) and to be brain sites at which local infusions of naloxone disinhibited LH release in ewes (Malven, 1988) were dissected separately and 3) natural endocrine states in cyclic ewes were used to create naloxone-reversible states of LH suppression (Malven et al, 1984;Currie and Rawlings, 1987).…”

Section: Methodsmentioning

confidence: 99%

Specific Binding of Naloxone to Ovine Brain Tissue: Comparison of Brain Regions and Endocrine States

We²,

Pv³

1989

Journal of Animal Science

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Binding of [3H]naloxone ([3H]NAL) to brain membranes was quantified by Scatchard analysis using two methods of separating bound from free [3H]NAL. In the centrifugation method, membranes that were soluble at 1,000 x g, but sedimented at 20,000 x g, were incubated with [3H]NAL. For filtration, all membranes that sedimented at 20,000 x g were incubated and filtered through glass filter fibers. Nonspecific binding was estimated using greater than 500-fold excess of unlabeled naloxone (10(-6) M). Specific binding of [3H]NAL was used to generate linear multiple-point Scatchard plots, which indicated a single class of high-affinity sites. In Exp. 1, 10 ovariectomized (OVX) ewes were injected with estradiol-17 beta alone or in combination with progesterone. Compared with OVX controls, these hormonal treatments did not affect binding of [3H]NAL (centrifugation method) to combined hypothalamus (HYP) + preoptic (POA) tissues. In cyclic ewes (Exp. 2, filtration method), affinity constants (2.4 +/- .2 x 10(8) M-1) did not differ among HYP, POA and basal forebrain (BF) tissues, but BF had more sites (39 +/- 3 fmol/mg) than either HYP (14 +/- 1) or POA (17 +/- 1). Binding affinity and concentration of sites within each brain area (HYP, POA, BF) did not differ between d 8 and d 16 (preovulatory but after luteolysis) in normally cycling ewes. Overall, neural tissue dissected from BF had a greater concentration of binding sites than HYP or POA. Exogenous and endogenous fluctuations in ovarian steroids did not affect binding of [3H]NAL to these tissues.

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Quantification of Naloxone Binding Sites in Brains from Suckled Beef Cows during Postpartum Anestrus and Resumption of Estrous Cycles

Cited by 12 publications

References 20 publications

Distribution of β-Endorphin Immunoreactivity in the Arcuate Nucleus and Median Eminence of Postpartum Anestrus and Luteal Phase Cows

Distribution of β-Endorphin Immunoreactivity in the Arcuate Nucleus and Median Eminence of Postpartum Anestrus and Luteal Phase Cows

Luteinizing hormone and growth hormone secretion in early lactating Spanish beef cows

Specific Binding of Naloxone to Ovine Brain Tissue: Comparison of Brain Regions and Endocrine States

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