Patterns of LH and FSH Release from Perifused Rat Pituitaries in Response to Infusions of Hypothalamic Extract1,2

Dowd, Allen J.; Barofsky, Anna Lisa; Chaudhuri, Ν. Κ.; Lloyd, Charles W.; Weisz, Judith

doi:10.1210/endo-96-2-243

Cited by 30 publications

(16 citation statements)

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“…Fragments of anterior pituitary tissue were incubated in vitro using a continuous flow (perifusion) system based on that of Dowd et al [7]. The perifusion medium (medium 199 with Hanks' salts: Gibco) was buffered with NaHCO> (final concentration, 0.0174 M) and contained additional quantities of KC1 (final concentration, 0.0162 M), pencillin G (0.25 g/l; Squibb), streptomycin sulfate (0.135 g/1; Gibco) and bacitracin (2x 10'5 M; Sigma).…”

Section: Methodsmentioning

confidence: 99%

Stimulation of Prolactin Secretion in Rhesus Monkeys by Vasoactive Intestinal Polypeptide

Frawley

Neill

1981

Neuroendocrinology

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Vasoactive intestinal polypeptide (VIP) is a potent stimulus for prolactin (PRL) release in rats. The purpose of this study was to test the effect of VIP on PRL secretion in rhesus monkeys and to identify its site of action. Three experimental models were used: (1) intact monkeys during the follicular phase of the menstrual cycle; (2) female, hypophyseal stalk-transected, ovariectomized monkeys (ST-OVX), and (3) monkey pituitary tissue perifused in vitro. Initial serum concentrations of immunoreactive PRL were more than 10-fold higher for ST-OVX monkeys (52.4 ± 10.4 ng/ml, X ± SEM; n = 6) than for intact monkeys (4.79± 1.0 ng/ml; n = l0). Intravenous administration of VIP(20 μg/kg body weight) induced an elevation of circulating PRL in each of the intact and ST-OVX monkeys tested. On the average, VIP treatment evoked more than a 9-fold rise in serum PRL in intact monkeys (p < 0.01) and more than a 2-fold increase in ST-OVX monkeys (p < 0.01), while injection of vehicle alone did not affect PRL levels in either experimental group. Addition of VIP (5 × 10^–9 – 5 × 10^–6M) to medium perifusing monkey pituitary tissue in vitro stimulated PRL secretion both in the presence and in the absence of dopamine (2.5 × 10^–7M).Furthermore, the in vitro potency of VIP was comparable, on a molar basis, with that of thyrotropin releasing hormone. Collectively, these results indicate that VIP is a potent stimulus for PRL secretion in monkeys which exerts its effect, at least in part, by a direct action at the pituitary level. Therefore, VIP should now be considered as a possible PRL releasing factor in primates.

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Section: Methodsmentioning

confidence: 99%

Stimulation of Prolactin Secretion in Rhesus Monkeys by Vasoactive Intestinal Polypeptide

Frawley

Neill

1981

Neuroendocrinology

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“…Whilst the significance of basal (unstimulated) secretion from pituitaries incubated in vitro is not clear and may simply reflect passive diffusion of stored FSH, there is growing evidence that pituitary FSH secretion may, in part, be independent of releasing factors (Yen et al, 1972;Steinberger et at., 1973;Dowd et al, 1975;Shahmanesh and Jeffcoate, 1976;Franchimont, 1977;de Jong et al, 1979). The findings presented here may be interpreted to suggest that in the rat, inhibin, at least in part, acts by reducing the LH-RH independent release of FSH.…”

Section: Discussionmentioning

confidence: 66%

Feedback Control of FSH Secretion in the Male Rat

Shahmanesh¹,

Sedigh²,

Azedeh³

et al. 1980

Horm Res

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Site of feedback control of FSH secretion in the male rat was studied by measuring changes in serum LH, FSH and hypothalamic LH-RH by radioimmunoassay in rats after castration and after 500 rad X-irradiation to the testis. The rise in serum LH and FSH in castrated animals was associated with a significant fall in hypothalamic LH-RH 16 and 24 days after castration. Serum FSH rose significantly after X-irradiation without a significant change in serum LH or hypothalamic LH-RH content up to 30 days after irradiation. When pituitary halves from X-irradiated animals were incubated in vitro in the presence or absence of synthetic LH-RH, there was a significant rise in FSH (but not LH) released in the incubation medium in the absence of added LH-RH. The response of the pituitaries to LH-RH was, however, not different between control and irradiated rats. It is concluded that the testicular FSH-inhibitory substance acts predominantly at the pituitary gland on the LH-RH independent release of FSH.

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“…Studies uti lizing superfusion of pituitary fragments have both demon strated [2. 30] and failed to demonstrate [5] a self-priming effect. Perifusion of dispersed pituitary cells has also pro duced variable results [10, 17.…”

Section: Discussionmentioning

confidence: 99%

Androgenic and Estrogenic Control of the Self-Priming Effect of LHRH in the Castrated Male Rat

Nazian¹

1986

Neuroendocrinology

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Intact pubertal or young adult male rats release more luteinizing hormone in response to luteinizing hormone releasing hormone (LHRH) if pretreated with LHRH than if pretreated with saline. Castrated male rats do not show this self-priming effect of LHRH. In an attempt to determine the testicular factor responsible for the maintenance of the self-priming effect, pubertal male rats were castrated and implanted subcutaneously with various sizes of testosterone-filled Silastic capsules. Control rats were castrated or sham-operated and implanted with empty capsules. Rats were examined for a self-priming effect 4 days later. All sizes of testosterone capsules used maintained the self-priming effect. Three additional experiments were performed to determine the ability of dihydrotestosterone, estradiol and androstenedione to maintain a self-priming effect. The following groups were included in each experiment: castrated plus empty capsule, castrated plus testosterone-filled capsule, castrated plus one of two sizes of capsule filled with the steroid of interest, and sham-operated plus empty capsule. Dihydrotestosterone and estradiol, but not androstenedione were capable of maintaining a self-priming effect. Since it is generally considered that dihydrotestosterone cannot be aromatized to estrogen, this action of estradiol and dihydrotestosterone is probably accomplished by different mechanisms.

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Patterns of LH and FSH Release from Perifused Rat Pituitaries in Response to Infusions of Hypothalamic Extract1,2

Cited by 30 publications

References 0 publications

Stimulation of Prolactin Secretion in Rhesus Monkeys by Vasoactive Intestinal Polypeptide

Stimulation of Prolactin Secretion in Rhesus Monkeys by Vasoactive Intestinal Polypeptide

Feedback Control of FSH Secretion in the Male Rat

Androgenic and Estrogenic Control of the Self-Priming Effect of LHRH in the Castrated Male Rat

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