Purification of Prolactin-Releasing and Inhibiting Factors from Beef12<sup>1</sup>,<sup>2</sup>

Dular, Ram; LaBella, Frank S.; Vivian, Stanley; Eddie, Lawrence W.

doi:10.1210/endo-94-2-563

Cited by 24 publications

(14 citation statements)

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“…Thus, the presence of PIF was suspected. When the acetic acid extract of bovine hypothalami was applied to Sephadex G-10 column, PIF was eluted earlier than PRF (Dular et al 1974), but when the methanolic extract of porcine hypothalami was applied to Sephadex G-25 column, PRF was eluted earlier than PIF. Either way, it is implied that PIF and PRF exist in the hypothalamus.…”

Section: Discussionmentioning

confidence: 89%

“…It has already been proved in a study using the bovine material that PRF is a polypeptide (Dular et al 1974) . That is, Dular et al isolated peptide from the acetic acid extract of bovine hypothalami with Sephadex G-25 column, and further isolated and purified PRF from the fraction with Sephadex G-10, cellulose phosphate and QAE-Sephadex column.…”

Section: Discussionmentioning

confidence: 97%

mentioning

confidence: 99%

“…prolactin; prolactin releasing factor; hypothalamus; lactation and pregnancy There have been papers on the isolation and extraction of prolactin inhibiting factor (PIF) and prolactin releasing factor (PRF) by Sephadex gel filtration, using bovine and porcine hypothalami as material (Dular et al 1974; Machlin et al 1974). However, it is not always easy to extract PRF, because PRF is suspected to be masked by PIF even in the isolation and purification of the factors with the Sephadex G-25 column (Dular et al 1974). We had already proved PRF to be predominantly present in the hypothalamus of rats in late pregnancy (Takahashi et al 1975(Takahashi et al , 1976a, and also rat PRF appeared to be most probably a relatively low molecular polypeptide (Takahashi et al 1976a, b), so an attempt was made to purify the PRF with Sephadex G-25 column, and also to determine its molecular weight.…”

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confidence: 99%

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Purification of rat prolactin releasing factor by gel filtration.

Takahashi

Wakai

Furuhashi

et al. 1978

Tohoku J. Exp. Med.

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Tohoku J. exp. Med., 1978, 126 (1), 77-84 -Pregnant rat hypothalamic fragments were extracted with 30 mM Tris-HCl buffer at pH 7.8, subjected to enzymatic digestion, and applied to gel filtration on Sephadex G-25 for purification of the prolactin releasing factor.Effect of the eluted fractions on the release of prolactin were tested by the determination of serum and pituitary prolactin after the injection in lactating rats.Prolactin was estimated by radioimmunoassay.One fraction (tube number 61-73) eluted later than synthetic ACTH enhanced release of prolactin 30min after injection, but other fractions had no effect on the release of prolactin.Prolactin releasing factor would be quan titatively predominant over prolactin inhibiting factor in pregnant rat. prolactin; prolactin releasing factor; hypothalamus; lactation and pregnancy

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Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 97%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Purification of rat prolactin releasing factor by gel filtration.

Takahashi

Wakai

Furuhashi

et al. 1978

Tohoku J. Exp. Med.

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“…Sephadex G-10 and G-25 columns, being separated from PIF (Dular et al 1974;Machlin et al 1974). Several authors reported that TRH has properties of PRF (Noel et al 1974;Rabello et al 1974;Refetoff et al 1974).…”

Section: Discussionmentioning

confidence: 99%

Relationship between prolactin secretion and hypothalamic prolactin releasing factor in pregnant and puerperium rats.

Takahashi¹,

Saito²,

Wakai³

et al. 1976

Tohoku J. Exp. Med.

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The present study attempted to elucidate stimulatory factor(s) in the rat hypothalamus which controls prolactin secretion from the anterior pituitary.Rat serum prolactin was elevated so much in late pregnancy that we prepared the hypothalamic extract of late pregnant rats. Prolactin levels in serum and pituitary were determined by radioimmunoassay. After injection of this extract into a lactating rat 43-60 hr after delivery, the serum prolactin level was elevated significantly one to four hr later and the pitui tary prolactin level declined two hr later. On the other hand, the hypothalamic extract of normal female rats prepared in a similar manner inhibited prolactin secretion from the anterior pituitary in the lactating rat as described by other authors.These data indicate that the prolactin releasing factor may consist in the hypothalamus of late pregnant rat, and be predominant over the prolactin inhibiting factor during late pregnancy. Prolactin secretion was also investigated in lactating and non-lactating puerperium rats. Prolactin in serum and pituitary declined with days after delivery in non-lactating rats, but not in lactating rats. The presumed factor for such prolactin release in lactating rats is considered to be the prolactin releasing factor. prolactin; prolactin releasing factor; hy pothalamus; lactation and pregnancyThe predominantly inhibitory influence of the hypothalamus on prolactin secretion from the pituitary has been well established.The stimulatory factor, however, was recently reported.The participation of serotonergic neurons appears to be important in the neuronal events leading to this hypothalamic stimulation of prolactin release (Lu and Meites 1973;Krulich 1975). In addition, oral admin istration of 5-hydroxytryptophan, a precursor of serotonin, significantly increases plasma prolactin (Kato et al. 1974).Although evidence of the hypothalamic regulation of prolactin secretion is generally accepted, there has been no establishment of hypothalamic control during pregnancy when prolactin secretion increases. In the present study, the prolactin releasing factor (PRF) in the hypothalamus was investigated using late pregnant

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