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Plasma and pineal melatonin (MEL) and selected pineal neurochemicals (5-hydroxytryptophan, serotonin, N-acetylserotonin, dopamine, norepinephrine) associated with MEL synthesis were determined in steers grazing Acremonium coenophialum (endophyte)-infected 'Kentucky-31' tall fescue paddocks. Paddock treatments included low (LE, 33%) or high (HE, 74%) endophyte at either low (134 kg.ha-1 x yr-1, LN) or high (335 kg.ha-1 x yr-1, HN) nitrogen fertilization. Twelve pairs of yearling Angus steers were randomly assigned to three replications of the paddock treatments (LEHN, HEHN, LELN, and HELN). One steer in each of the 12 paddocks received per os either a dopamine antagonist, metoclopramide (MC; 15 mg/kg), or sucrose (S; 15 mg/kg) three times weekly for 10 wk. Blood was collected via jugular cannulas during the day and night for plasma MEL analysis and pineal glands were collected at termination. Day and night plasma MEL in the S/HEHN steers was reduced by 31.7 and 35.4% (P < .05), respectively, compared with that in S/LEHN steers. Mean night plasma MEL in the S/HELN steers was reduced by 26.7% (P < .05) compared with that in S/LELN steers. Metoclopramide reduced mean day and night plasma MEL by 22.9 and 38.3% (P < .05), respectively, in the LEHN steers and increased night MEL in the HELN animals by 35.1% (P < .05). During the day and night, there was a MC x pasture treatment interaction (P < .05). No differences were observed in either pineal MEL or the pineal neurochemicals. Acremonium coenophialum-infected fescue reduced plasma concentrations of MEL in steers, whereas treatment with MC altered plasma MEL biphasically.(ABSTRACT TRUNCATED AT 250 WORDS)

SummaryWithin rats lactating 13 to 14 days, non-suckled mammary glands contained significantly more DNA than suckled glands, and this difference increased in a linear manner as the non-suckling interval increased from 0 to 12 hours. It is suggested that increased numbers of leucocytes account for this difference. The presence or absence of milk did not affect RNA content, and it is suggested that the rat mammary gland has the potential to secrete milk proteins at a constant rate up to 12 hours.

SummaryDNA content of mammary glands of rats lactating 41 or 61 days was not significantly different from that of glands of rats lactating 21 days (10.56 mg and 10.94 mg vs 11.03 mg). RNA content of mammary glands of rats lactating 41 or 61 days was highly significantly less than that of glands of rats lactating 21 days (49.76 mg and 44.83 mg vs 75.06 mg). Similarly, body weight gains of foster litters were less than those of original litters.

SummaryConcurrent pregnancy significantly enhanced mammary DNA and RNA in rats lactating 18 days when compared with non-pregnant rats lactating 18 days, but the RNA/DNA ratio was not changed. Concurrent pregnancy in rats lactating 21, 24, and 28 days produced, respectively, no change, significant decrease, and no change in nucleic acid content when compared with lactating, non-pregnant rats. Within days 24 and 28 of lactation, nucleic acid content decreased markedly with advancing pregnancy.Standardization of gestation length showed that glands of rats with 7 or more fetuses contained highly significantly less DNA and RNA than glands of lactating, non-pregnant rats.

SummaryTotal DNA of rat mammary glands per 100 g of body weight increased from 2.77 mg to 7.89 mg during pregnancy, a 184.8% increase, and total DNA increased from 4.76 mg to 17.19 mg, a 261.1% increase. Total RNA increased from 3.06 mg to 15.44 mg during pregnancy and these increases paralleled those of total DNA. RNA/DNA ratio increased from 0.64 to 0.90 as gestation advanced.

SummaryTotal mammary DNA per 100 g of body weight increased 9.8% from day 20 of pregnancy to day 1 of lactation and 25.9% from day 1 to day 4 of lactation. Ovariectomy on day of parturition had no influence on mammary hyperplasia during early lactation. On the basis of total DNA per 100 g of body weight maximum mammary development occurred on day 8 of lactation (11.51 mg) and 24.8% of mammary growth occurred during lactation. No significant decrease occurred in mammary DNA until after day 24 of lactation. With the onset of lactation total mammary RNA increased much more rapidly than did total mammary DNA. Maximum mammary RNA content was observed on day 21 of lactation (75.06 mg) after which it declined precipitously to day 28 of lactation (39.61 mg). Mammary gland RNA/DNA ratio increased rapidly when lactation was initiated (1.24), attained its maximum on day 21 of lactation (2.95) and then decreased to day 28 of lactation (1.96). It is suggested that RNA/DNA ratios, when plotted against stage of lactatio...

SummaryTeat ligation of 3 abdominal-inguinal mammary glands of lactating rats markedly decreased DNA and RNA content and RNA/DNA ratio when compared with similar estimates of either contralateral, non-ligated glands or glands from normal rats lactating the same length of time. Suckling stimulus, without milk removal, did not prevent cellular loss and did not maintain level of protein synthesis. DNA and RNA content and RNA/DNA ratio of contralateral, non-ligated glands were greater than those of glands of normal rats lactating comparable periods of time.

SummaryDNA per 100 g of body weight and total DNA in 6 abdominalinguinal mammary glands one day after weaning did not differ significantly from that of glands on the 21st day of lactation. DNA content decreased significantly 3 days after weaning. On the 21st day of involution mammary DNA per 100 g of body weight was similar to that of glands from sexually mature virgin rats. One day after weaning RNA content decreased 26.2% and on the 21st day of involution it approximated that of glands from sexually mature virgin rats. RNA/DNA ratio was reduced 31.9% one day after weaning and by the 12th day it was lower than that of glands from sexually mature virgin rats.