Pituitary Lactogenic Hormone Release During Onset of Pseudopregnancy in Intact Rats

Herlyn, U.; Geller, H. F.; Berswordt-Wallrabe, Ilse v.; Berswordt-Wallrabe, R. von

doi:10.1530/acta.0.0480220

Cited by 15 publications

(9 citation statements)

References 2 publications

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“…Pituitary prolactin concentration did not decrease until 24 hr after the induction of pseudopregnancy. This is contrary to the findings of Herlyn et d. (3) who observed a significant decrease in pituitary prolactin content within 30 min after glass rod stimulation of the cervix. The method of stimulation or the strain of rats may have made the difference; however, Taleisnik et al (8) did not find any evidence of LH release in rats 1 hr after a glass rod stimulation of cervix although normal mating resulted in a significant discharge of the hormone.…”

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confidence: 99%

“…The data suggest that prolactin in rats may be involved in Since the original work with amphenone ( 1) and related compounds such as metyrapone, a large number of substances were shown to modify the pattern of steroidogenesis in the adrenal [Refs. (2,3)]. One of these, designated Su-10603, synthesized by Bencze and Barsky (4) had considerable activity as an adrenal 17~-hydroxylase inhibitor both in vivo and in vitro (5-7).…”

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Changes in Pituitary Prolactin and Mammary Nucleic Acid Content during Pseudopregnancy in the Rat

Sinha

Schmidt

1969

Experimental Biology and Medicine

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During pseudopregnancy in the rat, ovulation is suppressed and the corpora lutea are maintained, presumably under the influence of prolactin. Schwartz and Rothchild (1) observed a steady rise in the pituitary concentration of luteinizing hormone (LH) during pseudopregnancy, reflecting a reduction in LH release which prevented ovulation. The mammary gland, another target organ of prolactin, also grows during pseudopregnancy. The extent of growth is comparable to that during the first 11-1 2 days of pregnancy (2). Although a sharp decrease in pituitary prolactin concentration at the induction of pseudopregnancy has been reported (3), no data for an extended period of time are available. Thus, the present study was undertaken to determine the changes in pituitary prolactin content during the entire course of pseudopregnancy and its relationship to biochemical changes in the mammary gland.Materials and Methods. Adult rats of CFE strain obtained from Carworth Inc., New York City, N. Y. were used. Rats were maintained in a room lighted between 6 a.m. and 6 p.m. and received Agway rat and mouse pellets and water ad libitum. Stage of the estrous cycle was determined by daily examination of vaginal smears. Pseudopregnancy was induced by vibrating the cervix for 20-25 sec on the day of estrus with a glass rod attached to a dental drill (4). Rats that began cycling after stimulation were discarded.Rats in groups of eight were killed by decapitation immediately after stimulation, at 0.5, 2, 8, 16, and 24 hr, and at 2, 4, 6, 8, and 12 days after vibration of the cervix. One unstimulated group and one group showing proestrus smear after the termination of pseudopregnancy were also killed. The ante-* Supported by National Institutes of Health Grant HD 01940. rior pituitary glands were removed, weighed and stored at -20' for prolactin assay. The eight pituitaries from each group were pooled and prolactin was assayed by a modification of the method of Reece and Turner ( 5 ) using a four-point assay design. Low doses of pituitary (0.5 mg) and NIH-P-Ss ovine prolactinl (1.0 pg) were injected into right and left sides of the crop sacs, respectively, of eight adult pigeons (Homer breed), and high doses of pituitary (1.5 mg) and standard prolactin (3.0 pg) were injected similarly into eight additional birds. Potency and the several criteria of the validity of the assays were calculated by the method of Bliss (6).The six abdominoinguinal mammary glands were removed and analyzed for nucleic acids after separating the parenchyma from the surrounding connective tissue (7). The weights of the adrenal glands were recorded.Results. Anterior pituitary weights (Table I) increased slightly (not significant) 30 min after cervical vibration, remained high until 16 hr, and then gradually declined to a low value on day 10 of pseudopregnancy ( p < 0.01 ) . Adrenal weights declined 10% (p

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Changes in Pituitary Prolactin and Mammary Nucleic Acid Content during Pseudopregnancy in the Rat

Sinha

Schmidt

1969

Experimental Biology and Medicine

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“…In contrast to the LH results, paced mating did not selectively increase PRL over levels seen in non-paced and mounts-only females. Acute PRL increases (within 15 to 30min) have becn seen in mated (7) and cervically-stimulated (3,30) females, while in other studies, no acute PRL response has been observed (1 3, 15). In the present study.…”

Section: Matingmentioning

confidence: 77%

Acute Luteinizing Hormone and Prolactin Responses to Paced Mating Stimulation in the Estrous Female Rat

Erskine

Kornberg

1992

J Neuroendocrinology

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The present experiments sought to characterize the particular stimuli received during mating in the female rat which induce acute increases in luteinizing hormone (LH) and prolactin (PRL) following copulation. Comparisons were made between cycling females mated on the evening of proestrus in partitioned chambers in which spontaneous patterns of approach/withdrawal toward the male served to pace copulatory stimulation (paced), in non-partitioned chambers in which female regulation of intervals between copulatory mounts was prevented (non-paced), or under conditions in which they received mounts-without-intromission (mounts-only). Frequent blood samples were withdrawn via surgically implanted intra-atrial catheters. In experiment 1, blood samples for LH determinations were taken at 15-min intervals for 1 h prior to and for 2 h after mating on the evening of proestrus. In experiment 2, samples for PRL determinations were taken at 10-min intervals for 30 min prior to and for 90 min after mating on proestrus and at 0300, 0400 and 0500 h on the day of estrus (reported times corrected for reversed light cycle). LH levels were significantly higher in paced animals 15 min after initiation of mating than in non-paced and mounts-only females; no differences in LH were seen between females who subsequently became or did not become pregnant/pseudopregnant (P/PSP). PRL values were not different between groups receiving the different mating treatments at any time; however, P/PSP animals showed significantly higher levels of PRL between 20 to 60 min after mating than did non-P/PSP females. No differences in PRL were seen between mating treatments or pseudopregnancy condition at 0300 to 0500 h on estrus. Paced females in both experiments received intromissions at a significantly slower rate than did non-paced females. There was a significant positive correlation (r = 0.619, P<0.001) between LH concentration at 15 min and the inter-intromission interval (in seconds) in paced and non-paced groups of females. These data suggest that an LH response to mating is dependent upon the particular characteristics of mating stimulation received. In addition, they demonstrate that PRL increases acutely after mating stimulation in animals destined to become P/PSP but does not increase in response to those characteristics of mating stimulation which induced increases in LH.

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“…In rats, a rise in the plasma concentration of L H occurs within 5-10 min after coitus, and a slight rise in the FSH content of the pituitary is seen 1 hr after copulation (1). Pituitary L T H falls within 30 min after cervical stimulation ( 2 ) , whereas plasma progesterone rises 24 hr after mating (3).…”

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“…The nonprotein sulfhydryl (NPSH) level in the liver of mice administered endotoxin has been shown to decrease by nearly 25% within 2 hr and to fall to about 45% of normal in 18 hr (1,2 ) . A similar rapid decrease in the liver NPSH has been reported following a number of other stress conditions, such as, scalding or ligature of hind legs ( 2 ) .…”

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Postcopulatory Mammary Gland Secretion in Rats

Dilley¹,

Adler²

1968

Experimental Biology and Medicine

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Pituitary Lactogenic Hormone Release During Onset of Pseudopregnancy in Intact Rats

Cited by 15 publications

References 2 publications

Changes in Pituitary Prolactin and Mammary Nucleic Acid Content during Pseudopregnancy in the Rat

Changes in Pituitary Prolactin and Mammary Nucleic Acid Content during Pseudopregnancy in the Rat

Acute Luteinizing Hormone and Prolactin Responses to Paced Mating Stimulation in the Estrous Female Rat

Postcopulatory Mammary Gland Secretion in Rats

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