Elicitation of release of luteinizing hormone by N-methyl-d,l-aspartic acid during three paradigms of suppressed secretion of luteinizing hormone in the female pig

Sesti, L. A. C.; Britt, J.H.

doi:10.1016/0739-7240(92)90024-r

Cited by 15 publications

(13 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…of the excitatory amino acid analog N-methyl-D,L-aspartic acid (NMA; 10 mg/kg BW; Sigma Chemical Co., St. Louis, MO) in order to estimate releasable pools of GnRH stored in the median eminence [14]; and 2) sows (n = 5) given an injection (i.v., -30 ml) of 0.9% NaCl (control group). The NMA was dissolved in 0.9% NaCI immediately before injection at a concentration of approximately 90 mg/ml.…”

Section: Methodsmentioning

confidence: 99%

Secretion of Gonadotropins and Estimated Releasable Pools of Gonadotropin-Releasing Hormone and Gonadotropins during Establishment of Suckling-Induced Inhibition of Gonadotropin Secretion in the Sow

Sesti

Britt

1994

Biology of Reproduction

View full text Add to dashboard Cite

Two experiments were conducted to evaluate relationships between changes in hypothalamic GnRH, pituitary and serum gonadotropins, and ovarian function during the first week postpartum in lactating multiparous sows. In experiment 1, our hypothesis was that sows would have active LH secretion immediately after parturition and that suckling would inhibit LH concentrations within the first 3 days postpartum. Sows were killed at Day 1 (n = 5) or Day 7 (n = 5) of lactation, and blood samples were taken every 6 h from 48 h before parturition until 24 h (Day 1 sows) or 156 h (Day 7 sows) after parturition. Preoptic area (POA), medial basal hypothalamus (MBH), stalk median eminence (SME), anterior pituitary (AP), and ovaries were collected at slaughter. On Day 1, sows had fewer (p < 0.05) small follicles (< 4 mm diameter), but more (p < 0.05) medium (4-6 mm) and large (> 6 mm) follicles, than sows on Day 7 (20 +/- 2, 6.5 +/- 1.1, 2.5 +/- 0.7 vs. 26.3 +/- 3, 0, and 0, respectively). Serum LH and FSH decreased (p < 0.04) during the period from 24 to 48 h postpartum and remained low through Day 7. GnRH concentrations in POA, MBH, and SME and the proportion of residual GnRH released in vitro in response to K+ did not differ between Day 1 and 7. Weights of AP were not different, but pituitary concentrations (microgram/mg) of LH and FSH increased (p < 0.05) from Day 1 to 7 (LH: 0.27 +/- 0.03 vs. 0.44 +/- 0.01; FSH: 2.6 +/- 0.07 vs. 7.8 +/- 0.8, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

show abstract

Section: Methodsmentioning

confidence: 99%

Secretion of Gonadotropins and Estimated Releasable Pools of Gonadotropin-Releasing Hormone and Gonadotropins during Establishment of Suckling-Induced Inhibition of Gonadotropin Secretion in the Sow

Sesti

Britt

1994

Biology of Reproduction

View full text Add to dashboard Cite

show abstract

“…Administration of NMA induced a significant inle first week crease in circulating levels of LH in both primiparous and iment of the multiparous lactating sows. NMA does not act directly at the retion, which pituitary to elicit LH release (pig [11], rat and monkey [12,13], t is apparent hamster [30]); therefore, any change in LH secretion after NMA is due exclusively to NMA-induced activation of hypothalamic GnRH neurons [31,32]. The exact location of NMA receptors mediating the GnRH release is unknown, but early neuroexcitatory studies [13,33] and some recent reports [34,35] have indicated that NMA may preferentially bind to receptors in the arcuate nucleus and medial basal hypothalamus.…”

Section: Ng/ml; Andmentioning

confidence: 99%

“…; Sigma Chemical Co., St. Louis, MO) at Days 1 (within 20 h after the last piglet was born), 7, 14, and 21 of lactation. This dose was based on our previous dose-response studies in pigs [11] and was chosen because it induces a significant, repeatable release of GnRH without causing sustained observable side effects. Immediately before injection, NMA was dissolved in 0.9% NaCl (w/v) at a concentration of approximately 85 mg/ml.…”

Section: Animals and Experimental Proceduresmentioning

confidence: 99%

“…To estimate readily releasable pools of GnRH stored in the stalk median eminence [11], five sows were given infusions (i.v.) of NMA (10 mg/kg b.w.…”

Section: Animals and Experimental Proceduresmentioning

confidence: 99%

“…Readily releasable pools of GnRH were estimated by changes in secretion of LH after administration of N-methyl-DL-aspartic acid (NMA), a potent neuroexcitatory amino acid analog that elicits LH secretion by acting at the level of the hypothalamus to induce GnRH release [11][12][13]. Pituitary pools of gonadotropins were measured after a bolus injection of GnRH [14].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Agonist-Induced Release of Gonadotropin-Releasing Hormone, Luteinizing Hormone, and Follicle-Stimulating Hormone and their Associations with Basal Secretion of Luteinizing Hormone and Follicle-Stimulating Hormone throughout Lactation in Sows

Sesti

Britt

1993

Biology of Reproduction

View full text Add to dashboard Cite

Our working hypothesis was that the normal increase in basal secretion of LH and FSH during lactation in sows is paralleled by an increase in readily releasable pools of GnRH, LH, and FSH. Sows fitted with indwelling catheters and nursing 9-11 piglets were sampled on Days 1, 7, 14, and 21 (primiparous sows; n = 10; experiment 1) or Days 7 and 21 (multiparous sows; n = 10; experiment 2) of lactation. On each day, blood was collected at 10-min intervals for 2 h before one member of a pair of sows was infused (i.v.) with saline (n = 5) and the other with the neuroexcitatory amino acid N-methyl-DL-aspartic acid (NMA; 10 mg/kg b.w.) to measure readily releasable GnRH as estimated by LH release. Two hours later, each sow that had received saline was given GnRH (100 micrograms, i.v.) for estimation of releasable pools of pituitary LH and FSH. Responses to NMA and GnRH were estimated by area under the curve (ng.ml-1.min) of serum LH profiles for 1 h (NMA group) or 2 h (GnRH group) after treatment. Basal LH secretion in primiparous sows decreased from Day 1 to Day 7 and then returned to Day 1 values by Day 21. Similarly, in multiparous sows, basal LH was lower on Day 7 than on Day 21. Basal FSH secretion increased linearly as lactation progressed in primiparous and multiparous sows.(ABSTRACT TRUNCATED AT 250 WORDS)

show abstract

The Stimulatory Action of the Glutamate Agonist, N-Methyl-Aspartate, on Luteinizing Hormone Release in the Cockerel with Immunocytochemical Observations on Its Mode of Action

et al. 1997

View full text Add to dashboard Cite

Elicitation of release of luteinizing hormone by N-methyl-d,l-aspartic acid during three paradigms of suppressed secretion of luteinizing hormone in the female pig

Cited by 15 publications

References 29 publications

Secretion of Gonadotropins and Estimated Releasable Pools of Gonadotropin-Releasing Hormone and Gonadotropins during Establishment of Suckling-Induced Inhibition of Gonadotropin Secretion in the Sow

Secretion of Gonadotropins and Estimated Releasable Pools of Gonadotropin-Releasing Hormone and Gonadotropins during Establishment of Suckling-Induced Inhibition of Gonadotropin Secretion in the Sow

Agonist-Induced Release of Gonadotropin-Releasing Hormone, Luteinizing Hormone, and Follicle-Stimulating Hormone and their Associations with Basal Secretion of Luteinizing Hormone and Follicle-Stimulating Hormone throughout Lactation in Sows

The Stimulatory Action of the Glutamate Agonist, N-Methyl-Aspartate, on Luteinizing Hormone Release in the Cockerel with Immunocytochemical Observations on Its Mode of Action

Contact Info

Product

Resources

About