Disease relevance of PRL

• Seasonal changes in plasma levels of PRL, FSH, and cortisol, testis size, and body weight were also monitored; the seasonal cycle in the levels of immunoreactive beta-endorphin occurred in parallel with the cycle in plasma FSH and body weight [1].
• Hyperprolactinemia, produced by ovine PRL administration, resulted in marked increases in DA turnover rates in both the MEm (2.7-fold) and the MEl (4.7-fold) [2].
• In addition, the replication of Nb 2 Node rat lymphoma cells was stimulated by pineal PRL-like ir-material, an effect known to be specific for lactogenic hormones [3].
• In adult animal pituitaries or in cultured pituitary tumor cells, glucocorticoids are regulators of GH, PRL, and proopiomelancortin (POMC) synthesis [4].
• Further studies on DNCB contact sensitivity and on antibody formation revealed that the immunocompetence of BRC-suppressed animals could be restored by additional treatment with either prolactin (PRL) or growth hormone (GH) [5].

Psychiatry related information on PRL

• Locomotor activity was diurnal, inversely related to melatonin secretion, and prolactin levels were increased under long days [6].
• These results indicate that endogenous and exogenous opioids modulate cortisol release in nonstressed sheep, and cortisol and prolactin secretion in sheep subjected to psychological stress [7].
• Influence of the blood concentration of prolactin on the length of the sensitive period for establishing maternal behavior in sheep at parturition [8].
• Electroacupuncture-induced analgesia in sheep: measurement of cutaneous pain thresholds and plasma concentrations of prolactin and beta-endorphin immunoreactivity [9].
• Dopamine modulation of prolactin and vasopressin but not behavior on satiation of sheep [10].

High impact information on PRL

• Prolactin levels and duration of postpartum anoestrus in lactating ewes [11].
• The purified receptor bound 125I-oPL specifically and with high affinity (Kd 0.5 nM) but did not bind either radiolabeled ovine GH or ovine PRL [12].
• Purification of a distinct placental lactogen receptor, a new member of the growth hormone/prolactin receptor family [12].
• We administered 1 mg ovine PRL to 32 rabbit fetuses on day 24 of gestation and evaluated lung phospholipid synthesis and content on day 26 [13].
• Although supraphysiologic concentrations of PRL were achieved in plasma and amniotic fluid, there was no effect of this treatment on the flux of tracheal fluid surfactant or on plasma concentrations of corticoids of dehydroepiandrosterone sulfate [13].

Chemical compound and disease context of PRL

• The feasibility of using combinations of prepubertal measurements of body weight (BW), testicular size, and blood hormone concentrations (LH, FSH, PRL and testosterone) as indices of postpubertal reproductive function of rams was investigated [14].
• There was no inhibitory effect of either compound in basal medium or basal medium plus prolactin, indicating the absence of toxicity and that the inhibitory effect is specific for a progesterone-mediated process [15].
• Prolactin concentrations in foetal and neonatal sheep: effect of thyrotrophin releasing hormone, hypoxia and chlorpromazine [proceedings] [16].
• Maternal exposure to atrazine during lactation suppresses suckling-induced prolactin release and results in prostatitis in the adult offspring [17].
• Thus, dehydration enhances stress-induced prolactin release in sheep through a process that does not involve a pituitary action of CRF or circulating vasopressin [18].

Biological context of PRL

• The present study reports on the nucleotide sequence of o-PRL mRNA and the deduced amino acid sequence in the signal peptide of the hormone [19].
• Each dose of PRL was infused in a pulsatile manner, 4 x 50 microg/h and 4 x 100 microg/h, in 30-min intervals, respectively, during four consecutive days before oncoming ovulation [20].
• Cloning and nucleotide sequence of ovine prolactin cDNA [19].
• This putative function was concluded mainly from experiments in which mammalian PRL was injected into tadpoles or added to cultured tadpole tissues [21].
• In this study, we show that overexpression of ovine or Xenopus laevis PRL in transgenic X. laevis does not prolong tadpole life, establishing that PRL does not play a role in the life cycle of amphibians that is equivalent to that of juvenile hormone in insect metamorphosis [21].

Anatomical context of PRL

• These data indicate that maintenance of an increased PRL concentration within the central nervous system (CNS) for a few days before oncoming ovulation has no inhibitory effect on tonic LH secretion [20].
• However, overexpression of PRL produces tailed frogs by reversing specifically some but not all of the programs of tail resorption and stimulating growth of fibroblasts in the tail [21].
• The purpose of these experiments was to determine the effect of frontal hypothalamic deafferentation (FHD) between the suprachiasmatic-preoptic region and the mediobasal hypothalamus on diurnal, seasonal, and photoperiod-induced changes in PRL secretion in ewes [22].
• Since synthesis and secretion of GH and PRL were not diminished after HPD, it was considered that the pituitary gland remained viable and functioned independently of hypothalamic input in OVX ewes after HPD.(ABSTRACT TRUNCATED AT 400 WORDS)[23]
• During pregnancy, PRL receptors increased in the mammary gland up to day 100 [24].

Associations of PRL with chemical compounds

• A significant (p < 0.001) increase in IN/ME perfusate concentrations of dopamine and noradrenaline metabolites was noted in PRL-treated ewes in comparison with those in the control [20].
• The effects of prolonged, intracerebroventricular prolactin treatment on luteinizing hormone secretion, catecholaminergic activity and estrous behavior in ewes [20].
• Compared with diluent-injected littermates, PRL had no effect on the rate of choline incorporation into lecithin, tissue content of phospholipid and disaturated lecithin, or plasma corticoids [13].
• Prolactin (PRL) is widely considered to be the juvenile hormone of anuran tadpoles and to counteract the effects of thyroid hormone (TH), the hormone that controls amphibian metamorphosis [21].
• In conclusion, the decrease in ME dopaminergic activity associated with SD exposure or the SD-like effect of melatonin appears unrelated to the regulation of PRL secretion [25].

Physical interactions of PRL

• The fact that saturable binding could not be demonstrated for either GH or PRL with fetal liver microsomes contradicts recent suggestions that oPL is binding the GH receptor [26].
• Ovine placental lactogen is known to bind to prolactin receptors and to initiate milk synthesis in the rabbit mammary gland [27].

Regulatory relationships of PRL

• After injection, PACAP suppressed PRL and GH secretion so that plasma hormone concentrations from 1-3 h after injection were significantly different from the control (P < 0.05 for PRL, P < 0.01 for GH) [28].
• Transcription of the alpha s1-casein gene is induced by PRL [29].
• PRL was found to stimulate marked increases in alpha-lactalbumin production in six of eight specimens of mammary tissue from premenarcheal rhesus monkeys, and a lesser increase was seen in a seventh [30].
• Basal episodic profiles (pre-E beta) of LH, GH, and PRL were similar in ovx ewes infused with control or anti-NPY serum [31].
• A strong MGF-specific bandshift was obtained with nuclear extracts of COS cells induced with prolactin [32].

Other interactions of PRL

• In contrast, changes in the external photoperiod and circulating PRL concentrations in the sheep fetus do not directly alter PRLR expression in the fetal liver [33].
• These results suggest that PACAP acts in the arcuate nucleus region of the MBH, and not the rostral POA, to inhibit both LH and PRL secretion [34].
• However, POMC in the intermediate lobe (IL) and PRL in the AL are known to be primarily regulated by dopamine, via the D2 receptor, in adult sheep [35].
• A cooperation between distal and proximal regions of the alpha s1-casein gene is responsible for the PRL-dependent enhancer activity of the distal fragment [29].
• The secretory profile for PRL showed a close relationship with estradiol secretion.(ABSTRACT TRUNCATED AT 400 WORDS)[36]

Analytical, diagnostic and therapeutic context of PRL

• In this study we examined the heparin-binding properties of selected members of the PRL/GH family, using heparin affinity columns followed by gel electrophoresis/Western blotting [37].
• In contrast, the annual PRL cycle was not significantly affected by thyroidectomy or T(4) replacement [38].
• In the first experiment, LH and PRL secretion, hypothalamic tyrosine hydroxylase (TH) activity, and catecholamine contents were determined in ovariectomized estradiol-treated ewes either during long days (LD; control group) or after 5, 25, and 76 short days (SD) [25].
• Thyroidectomy and ovariectomy each reduced PRL binding activity in liver tissue significantly [39].
• GAL passive immunization selectively reduced the plateau phase of the preovulatory surge of PRL [40].

References