Time-Related Effects of Monosodium Glutamate on the Reproductive Neuroendocrine Axis of the Hamster*

Lamperti, Albert A.; Pupa, Lawrence E.; Tafelski, Thomas J.

doi:10.1210/endo-106-2-553

Cited by 12 publications

(12 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results from this study confirm our previous obser vations [II, 14,15] that female hamsters with a chemi cally-induced lesion of the ARC of the hypothalamus retain not only the neuroendocrine components involved in the normal regulation of LH secretion, but also a normal pitui tary LH response to LHRH both in vivo and in vitro. This is in contrast to the female rat given MSG neonatally in which LH secretion is impaired [4,6,7], and suggests that a species difference exists in these animals regarding their sensitivity to MSG on mechanisms regulating LH secretion.…”

Section: Discussionsupporting

confidence: 89%

“…Basal (no LHRH) and LHRH-stimulated release of LH and FSH were not differ ent between control and MSG-treated animals at any dose level. Brains of all MSG-treated animals demonstrated a le sion of the ARC that was similar to those reported else where [15].…”

Section: ); Given 25 Ng Lhrh (-------); Msg-trealed Animals: Givensupporting

confidence: 84%

“…These include: (1) the functional role of the ARC neurons not damaged by MSG (approxi mately 15% of the population [15]) remains to be resolved; (2) any functional alterations in the circumventricular or gans, which are known to be damaged by MSG in the mouse [22,23], have not been studied in our animal model; (3) neuroendocrine alterations resulting from MSG-in duced damage to the ganglion cells of the retina have not been studied extensively in the hamster. However, recent studies by Pickard, Turek, Lamperti and Silverman [unpub lished observations] have suggested that the retinohypothalamic system is functionally intact in MSG-treated hamsters in that these animals entrain and shift their 24-hour locomo tor activity to light-dark signals in a manner similar to con trols.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Pituitary Responsiveness to LHRH Stimulation in Hamsters Treated Neonatally with Monosodium Glutamate

Lamperti¹,

Baldwin²

1982

Neuroendocrinology

View full text Add to dashboard Cite

Previous studies have shown that neonatal administration of monosodium glutamate (MSG) results in a clearly defined lesion of the arcuate nucleus which disrupts mechanisms regulating normal FSH but not LH secretion in the adult female hamster. The present study was designed to investigate the effects of neonatally administered MSG or hypertonic saline (control) on the in vivo and in vitro responses to LHRH in adult animals. In order to evaluate these responses under a comparable hormonal background, all animals were ovariectomized at 2–3 months of age and given 50 µg of estradiol benzoate 3 weeks later. 24 h later, animals were anesthetized with sodium pentobarbital and a blood sample taken for baseline levels of gonadotropins; they were immediately given 5 or 25 ng LHRH intravenously, and LH and FSH responses to LHRH were determined by sampling at 15-min intervals over a 1-hour period. Pituitary content of LH and FSH was determined in a similar group of control and MSG-treated animals which did not receive the hypothalamic hormone. Basal LH secretion, the dose-response of LH to LHRH, and the pituitary concentration or content were similar in control and MSG-treated hamsters. In contrast to LH, basal FSH levels were significantly lower, the FSH responses to LHRHwere greatly attenuated, and a dose response to LHRH was absent in MSG-treated animals when compared to control values. Pituitary FSH concentration and content did not differ between control and MSG-treated animals. However, when pituitaries were removed, hemidissected, preincubated for 1 h, and incubated in the presence or absence of 8.5 × 10^-9 or 8.5 × 10^-10 M LHRHfor 3 consecutive 1-hour periods, no differences were noted between control and experimental animals regarding basal (no LHRH) or LHRH-stimulated release of LH and FSH. These results suggest that the decreased basal FSH levels and the attenuated FSH response to LHRH observed in vivo in MSG-treated animals may be due to an alteration in a neural or extraneural component which is involved in regulating the release of FSH by LHRH and which is evident in the absence of a functional arcuate nucleus and/or develops directly as the result of the neonatal administration of MSG.

show abstract

Section: Discussionsupporting

confidence: 89%

Section: ); Given 25 Ng Lhrh (-------); Msg-trealed Animals: Givensupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Pituitary Responsiveness to LHRH Stimulation in Hamsters Treated Neonatally with Monosodium Glutamate

Lamperti¹,

Baldwin²

1982

Neuroendocrinology

View full text Add to dashboard Cite

show abstract

“…There are, however, few reports describing the morphological characteristics of the ar-cuate nucleus and median eminence of the neonatal hamster, a species often used in studying the hypothalamic control of pituitary hormone secretion. Moreover this area of the hypothalamus is vulnerable to the neurotoxic effects of monosodium glutamate during the neonatal period with subsequent alterations in the secretion of hormones from the anterior pituitary gland (Lamperti et al, 1980). Therefore, it becomes imperative to understand and describe the morphology of this important area of the hypothalamus in untreated hamsters during the neonatal period prior to a detailed ultrastructural analysis of the time-related events that occur after injection of monosodium glutamate (Lamperti et al, 1980).…”

mentioning

confidence: 99%

Morphological changes in the hypothalamic arcuate nucleus and median eminence in the golden hamster during the neonatal period

Lamperti

Mastovich

1983

Am. J. Anat.

Self Cite

View full text Add to dashboard Cite

The purpose of the present investigation was to study the ultrastructure of the arcuate nucleus (ARC) and median eminence of hamsters on days 1-15 of the neonatal period. From days 1-6, the neurons of the ARC had large nuclei and a small amount of cytoplasm which contained polysomes, mitochondria, RER, lysosomes and Golgi complexes. From days 7-15 there was an increase in the amount of cytoplasm as well as more extensive Golgi complexes and RER. Astrocytes were the predominant glial component in both the ARC and median eminence. Astrocytic processes were in juxtaposition to unmyelinated axons, dendrites, and synapses. Axodendritic and axosomatic synapses containing clear vesicles were observed in the neuropil on day 1. There was an increase in the number of dense-core vesicles in the axonal endings beginning on day 4. Concomitantly, there were increasing numbers of clear and dense-core vesicles (64-70 nm) in terminals of the external layer of the median eminence, whereas larger dense-core vesicles (105-140 nm) were distinguishable by day 10 immediately dorsal to the external layer. The capillaries of the median eminence were composed of nonfenestrated endothelium from days 1-9. Fenestrae began to appear about day 10. Ependymal cells lining the third ventricle had pinocytotic vesicles, microvilli, and bleb-like protrusions on their apical surfaces. Ependymal processes were adjacent to nerve processes in the neuropil of the ARC and in the external layer of the median eminence, where they contacted the perivascular space. Two types of supraependymal cells were seen in animals throughout the neonatal period. One resembled a neuron which sent processes along the ependymal surface and often between cells. The second type was similar to a macrophage. The results of this study demonstrate the maturation of the neural elements in the ARC/median eminence area of the neonatal hamster.

show abstract

“…Since female hamsters with a lesion of the hypothalamic arcuate nucleus (ARC) have a selective inhibition of FSH secretion [18,20], experi ment II was designed to study FSH-and LH-releasing ac tivities in similar areas of the hypothalamus in this animal model.…”

mentioning

confidence: 99%

FSH- and LH-Releasing Activity in the Hypothalamus of Female Hamsters during Proestrus and Estrus: Effects of Arcuate Nucleus Lesions

Lamperti¹

1985

Neuroendocrinology

View full text Add to dashboard Cite

An in vitro bioassay was used to characterize the pattern of follicle-stimulating hormone (FSH)- and luteinizing hormone (LH)-releasing activities in the anterior (AH) and medial basal hypothalamus (MBH) during proestrus (P) and estrus (E) in the hamster. Regularly cycling hamsters were decapitated at 12.00, 16.00, 20.00 and 23.00 h of P and 02.00, 05.00, 08.00, 11.00, 14.00 and 17.00 h of E and sera assayed for FSH and LH. Neutralized extracts of the AH and MBH were incubated with a hemipituitary (HP), which was obtained from estrogen- and progesterone-primed ovariectomized rats. The incubation media were assayed for FSH and LH and the results expressed as nanograms of gonadotropin released per milligram HP. There was a surge of serum FSH and LH at 16.00 h of P and a surge of serum FSH only on E. LH-releasing activity in the AH and MBH declined late on P. This activity in the MBH increased by 08.00 h of E. FSH-releasing activity declined markedly in the MBH early on E when serum levels of FSH, but not LH, were rising. Conversely, low serum levels of FSH and high FSH releasing activity were found in the AH and MBH of animals with a chemically induced lesion of the arcuate nucleus. These data suggest that an FSH-releasing hormone may play an important role in the neuroendocrine control of FSH release.

show abstract

Time-Related Effects of Monosodium Glutamate on the Reproductive Neuroendocrine Axis of the Hamster*

Cited by 12 publications

References 12 publications

Pituitary Responsiveness to LHRH Stimulation in Hamsters Treated Neonatally with Monosodium Glutamate

Pituitary Responsiveness to LHRH Stimulation in Hamsters Treated Neonatally with Monosodium Glutamate

Morphological changes in the hypothalamic arcuate nucleus and median eminence in the golden hamster during the neonatal period

FSH- and LH-Releasing Activity in the Hypothalamus of Female Hamsters during Proestrus and Estrus: Effects of Arcuate Nucleus Lesions

Contact Info

Product

Resources

About