Pineal denervation by cervical sympathetic ganglionectomy suppresses the role of photoperiod on pregnancy or pseudopregnancy, body weight and moulting periods in the mink (Mustela vison)

1985 ◽  
Vol 107 (1) ◽  
pp. 31-39 ◽  
Author(s):  
L. Martinet ◽  
D. Allain ◽  
Y. Chabi
Keyword(s):  
Body Weight ◽  
Environmental Factors ◽  
Prolactin Secretion ◽  
Corpora Lutea ◽  
Progesterone Secretion ◽  
Cervical Ganglion ◽  
Cervical Sympathetic ◽  
Implantation Period ◽  
Short Days

ABSTRACT In mink, termination of the delayed implantation period, following reactivation of the corpora lutea, and onset of the spring moult are associated with a rise in prolactin secretion triggered by increasing daylength, while decreasing daylength induces the autumn moult. To establish whether suppression of the function of the pineal rendered the mink unresponsive to daylength changes, the superior cervical ganglion was removed bilaterally 2–4 weeks before mating. Intact and operated females were then left outdoors or were put under a lighting regime of either 15 h light: 9 h darkness (15L: 9D) or 8L: 16D. In July, at the end of the spring moult, the 15L: 9D lighting regime was changed to one of 8L: 16D. Under artificial photoperiods ganglionectomy suppressed the stimulatory role of long days and the inhibitory role of short days on prolactin secretion, and consequently on progesterone secretion and spring moult. Neither was the autumn moult, induced early in intact females by the change to a short photoperiod, advanced in ganglionectomized females, showing that the latter were unresponsive to the artificial modification of the photoperiod. However, in animals kept outdoors, prolactin and progesterone secretion and spring moult were not changed by ganglionectomy. Increase in body weight and autumn moult were only slightly delayed by the operation suggesting that other environmental factors had replaced the synchronizing effect of the daylength changes. Alternatively the desynchronization between intact females responsive to photoperiodism and those rendered unresponsive may be too slow to be observed soon after ganglionectomy. J. Endocr. (1985) 107, 31–39

Regulation of the photoperiod-induced cycle in the peripheral blood concentrations of β-endorphin and prolactin in the ram: role of dopamine and endogenous opioids

1990 ◽  
Vol 127 (3) ◽  
pp. 461-469 ◽  
Author(s):  
E. Ssewannyana ◽  
G. A. Lincoln
Keyword(s):  
Plasma Concentrations ◽  
Prolactin Secretion ◽  
Endogenous Opioids ◽  
Fold Change ◽  
Opioid Antagonist ◽  
Light Cycle ◽  
Blood Concentrations ◽  
The Mean ◽  
Short Days

ABSTRACT In a group of adult Soay rams housed indoors under an artificial light cycle of alternating 16-week periods of long and short days, there was a conspicuous longterm cycle in the peripheral plasma concentrations of β-endorphin and prolactin. The levels of β-endorphin were highest under short days and lowest under long days (15-fold change), and inversely related to the changes in the plasma levels of prolactin (120-fold change). The role of dopamine in the control of β-endorphin and prolactin was investigated in a series of experiments, conducted under both long and short days, in which rams were treated with dopamine receptor agonists (dopamine and bromocriptine) and antagonists (pimozide and sulpiride). Naloxone (opioid antagonist) was also administered to assess the additional involvement of endogenous opioids. Dopamine injected i.v. (6·6 mg/kg every 10 min) did not significantly affect the mean plasma concentrations of β-endorphin and prolactin under either long or short days. Pimozide (0·08 mg/kg i.m. every 2 h) caused a large increase in the mean plasma concentrations of β-endorphin and prolactin under long days but not short days. Naloxone (1·6 mg/kg, i.v.), administered alone or in combination with dopamine or pimozide, had no effect on the mean plasma concentrations of β-endorphin and prolactin, except under short days when, combined with pimozide, it induced an increase in the plasma concentrations of the two polypeptides. Bromocriptine (0·06 mg/kg, s.c.) caused a significant decrease in the plasma concentrations of both β-endorphin and prolactin; this effect was most marked at the times of increased secretion (under short days for β-endorphin and under long days for prolactin). Sulpiride (0·59 mg/kg, s.c.) produced the converse effect and caused an increase in the plasma concentrations of β-endorphin and prolactin with the amplitude and duration of the effect varying with the stage of the photoperiod-induced cycle. From these results in the Soay ram, we conclude that dopamine inhibits β-endorphin and prolactin secretion by way of D2 receptors under both long and short days. Endogenous opioids interact with dopamine, augmenting this inhibition under short days. Differences in the acute responses in the secretion of β-endorphin and prolactin, and the inverse relationship between β-endorphin and prolactin during the cycle, indicate that different regulatory systems involving dopamine influence the two pituitary polypeptides. Journal of Endocrinology (1990) 127, 461–469

SUPPRESSION OF PROGESTERONE SECRETION IN LACTATING RATS BY ADMINISTRATION OF ERGOCORNINE AND THE EFFECT OF PROLACTIN REPLACEMENT

1975 ◽  
Vol 65 (2) ◽  
pp. 155-161 ◽  
Author(s):  
H. TOMOGANE ◽  
K. ÔTA ◽  
A. YOKOYAMA
Keyword(s):  
Milk Production ◽  
Venous Blood ◽  
Experimental Period ◽  
Prolactin Secretion ◽  
Corpora Lutea ◽  
Undetectable Level ◽  
Stage Of Lactation ◽  
Progesterone Secretion ◽  
Treatment Administration ◽  
Very High

SUMMARY In order to assess the stimulatory effect of prolactin on the secretion of progesterone from corpora lutea in lactating rats, ergocornine maleate (ECO; 1 mg/day), an inhibitor of prolactin secretion, was administered subcutaneously on days 6 and 7 of lactation in primiparous rats. By day 8 of lactation, the concentration of progesterone in ovarian venous blood fell to an undetectable level in the ECO-treated animals, while the concentration in the control animals was very high at this stage of lactation. The level of 20α-hydroxypregn-4-en3-one was significantly higher on day 8 of lactation in ECO-treated than in control rats. Lactational dioestrus was interrupted by treatment with ECO and vaginal oestrus appeared 3–4 days after the start of treatment. Administration of ECO caused deleterious depression of milk production and of food intake of mother rats. In the pair-fed control animals, lactation continued almost normally throughout the experimental period. Prolactin (1 mg/day) administered simultaneously with ECO increased progesterone to levels even higher than those in control rats and restored 20α-hydroxypregn-4-en-3-one levels to those of the controls. The effect of the drug on milk production was alleviated. The results strongly suggest that prolactin is the most important factor in maintaining the function of corpora lutea in the lactating rat.

scholarly journals EPIDEMIOLOGICAL FEATURES OF COMMUNITYACQUIRED PNEUMONIA UNDER EXTREME NATURAL-CLIMATIC CONDITIONS

2017 ◽  
pp. 53-56
Author(s):  
R.S. Rakhmanov ◽  
N.N. Potekhina ◽  
I.A. Grishin ◽  
Yu.G. Piskarev ◽  
V.N. Basalyga ◽  
...  
Keyword(s):  
Body Weight ◽  
Environmental Factors ◽  
Community Acquired Pneumonia ◽  
Climatic Conditions ◽  
Natural Resistance ◽  
Seasonal Prevalence ◽  
Climate Conditions ◽  
Epidemiological Features ◽  
Causative Agents

The authors evaluated epidemiological features of community-acquired pneumonia (CAP) in organized groups under hot and wet conditions of Black Sea climate as well as under maritime climate conditions of Kamchatka. Persons of first group were not adapted to activity conditions and not acclimatized, but persons of second group were acclimatized and adapted to activity conditions. It was established that environmental factors caused incidence rate, seasonal prevalence, phase of ascent during period of adaptation, prevalence of causative agents. CAP incidence among persons with body weight deficiency, its onset in stress situations, high associativity of opportunistic microorganisms in etiological structure provided evidence about a role of natural resistance of human body. It was found a necessity of application of means of non-specific and specific prevention taking into consideration etiological role of causative agents both in different times during period of adaptation and taking into account season.

Effects of placing micro-implants of melatonin in the mediobasal hypothalamus and preoptic area on the secretion of prolactin and β-endorphin in rams

1992 ◽  
Vol 134 (3) ◽  
pp. 437-448 ◽  
Author(s):  
G. A. Lincoln ◽  
K.-I. Maeda
Keyword(s):  
Body Weight ◽  
Preoptic Area ◽  
Plasma Concentrations ◽  
Prolactin Secretion ◽  
Early Summer ◽  
Mediobasal Hypothalamus ◽  
Continuous Administration ◽  
Blood Concentrations ◽  
Micro Implants ◽  
Short Days

ABSTRACT In a previous study, we showed that the local administration of melatonin into the mediobasal hypothalamus (MBH), but not the preoptic area (POA), caused a premature increase in the secretion of FSH and growth of the testes in sexually inactive Soay rams exposed to long days. To extend these observations, we have now measured blood concentrations of prolactin and β-endorphin and the associated peripheral responses in the same animals, to establish whether the treatments produced multiple endocrine changes such as those which occur following exposure to short days. Groups of rams were initially exposed to alternating 16 weekly periods of long days (16 h light: 8 h darkness; 16L:8D) and short days (8L:16D) for at least 9 months to entrain the seasonal cycles in the secretion of the pituitary hormones. The treatments were started at 10 weeks under long days, when the animals had a physiology characteristic of the early summer with high blood plasma concentrations of prolactin (associated with growth of the summer pelage), and low concentrations of β-endorphin (associated with low body weight). The animals were assigned at random to the following treatments: (i) micro-implants of melatonin in the MBH, (ii) microimplants of melatonin in the POA, (iii) empty implants in the MBH or POA to act as operated controls, and (iv) no surgery to act as unoperated controls (n=12 rams/treatment). The micro-implants consisted of 22-gauge stainless-steel needles with melatonin fused inside the tip. The implants were inserted bilaterally in the brain, and left in place for 12–14 weeks. The observations continued for a total of 28 weeks while the animals remained under long days. The administration of melatonin in the MBH induced a rapid decrease in plasma concentrations of prolactin while in the POA it induced a less marked but significant effect. The mean times to minimum concentrations of prolactin were 7·4±0·4, 17·3±2·8 and 26·0 ±0·3 weeks for the MBH, POA and combined control groups respectively (MBH vs control, P<0·001, POA vs control P<0·01. In the MBH group, the concentrations of prolactin subsequently increased to a maximum 6 weeks after the end of melatonin treatment. The changes in prolactin were accompanied by changes in growth and moulting of the pelage; only animals in the MBH group showed a conspicuous moult associated with the change from low to high prolactin secretion. There was also a marked effect of melatonin when given into the MBH, but not the POA, on plasma concentrations of β-endorphin, which was correlated with differences between groups in the cycle in body weight. In conclusion, continuous administration of melatonin into the MBH acts like a long-duration melatonin signal and induces a full sequence of biological responses normally evoked by transfer to short days. This is used as evidence that melatonin acts within or close to the MBH to induce the multiple effects of photoperiod in the ram. Journal of Endocrinology (1992) 134, 437–448

SERUM LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE, PROLACTIN AND PROGESTERONE CONCENTRATIONS AND FOLLICULAR DEVELOPMENT IN THE PSEUDOPREGNANT RAT AFTER UNILATERAL OVARIECTOMY

1975 ◽  
Vol 66 (2) ◽  
pp. 249-256 ◽  
Author(s):  
W. J. DE GREEF ◽  
J. DULLAART ◽  
G. H. ZEILMAKER
Keyword(s):  
Follicular Development ◽  
Prolactin Secretion ◽  
Corpora Lutea ◽  
Follicular Growth ◽  
Unilateral Ovariectomy ◽  
Progesterone Secretion ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
Follicular Size ◽  
Limited Degree

SUMMARY Serum LH, FSH, prolactin and progesterone concentrations and follicular size were measured in rats during pseudopregnancy after unilateral ovariectomy (ULO) on day 1. This operation did not affect the duration of pseudopregnancy. Following pseudopregnancy compensatory ovulation occurred. After ULO progesterone concentrations remained low as compared with control values but the progesterone secretion per ovary was increased slightly. After ULO, LH concentrations were significantly increased on days 3 and 4 of pseudopregnancy. FSH concentrations were increased 5 h after the operation and again on days 4–7 of pseudopregnancy when compared with sham-operated control animals. During pseudopregnancy prolactin secretion increased each night. Increased prolactin levels were observed 18 and 36 h after ULO. The number of medium-sized follicles had increased 24 h after ULO. From the present study it is concluded that progesterone secretion by the corpora lutea can be increased to a limited degree by the increased release of gonadotrophins. Furthermore, it is concluded that a rapid increase in FSH concentrations after ULO is responsible for the initiation of the compensatory follicular growth.

Different mechanisms for the inhibition of progesterone secretion by ACTH and corticosterone in pregnant rats

1991 ◽  
Vol 129 (3) ◽  
pp. 405-410 ◽  
Author(s):  
N. Sugino ◽  
H. Tamura ◽  
Y. Nakamura ◽  
K. Ueda ◽  
H. Kato
Keyword(s):  
Direct Effect ◽  
Inhibitory Effect ◽  
Corpora Lutea ◽  
Serum Concentrations ◽  
Inhibitory Effects ◽  
Pregnant Rats ◽  
Progesterone Secretion ◽  
Co Addition

ABSTRACT The present study investigated possible sites through which ACTH or corticosterone inhibit progesterone secretion in pregnant rats, and the role of placental factors in blocking the inhibitory effect. The number of conceptuses was adjusted to one (1C group) or more than ten (FC group) on day 7 of pregnancy by aspirating the desired number. Serum concentrations of progesterone, testosterone and oestradiol were significantly (P<0·01) lower on day 15 in the 1C group than in the FC group. Corpora lutea (CL) obtained on day 15 were incubated for 6 h with corticosterone or ACTH. Corticosterone (1 μmol/l) significantly (P<0·05) inhibited progesterone secretion in the IC group but not in the FC group. The inhibitory effect of corticosterone in the IC group was completely blocked by co-addition of 1 μmol testosterone/l or 1 μmol oestradiol/l but not by 1 μmol dihydrotestosterone/l. ACTH (1 μg/l–1 mg/l) had no direct effect on progesterone secretion in either the IC or the FC groups, although ACTH apparently decreases progesterone secretion in vivo. Placentae obtained from rats of the FC group on day 15 were incubated for 24 h with or without ACTH (1 mg/l). The supernatant after placental incubation without ACTH significantly (P<0·01) increased progesterone secretion by the CL in both the IC and FC groups, and also eliminated the inhibitory effect of corticosterone in the IC group. The supernatant after placental incubation with ACTH also increased progesterone secretion in the FC group as effectively as the supernatant from the control incubation, but it had no effect in the IC group. It is concluded that corticosterone directly inhibits progesterone secretion by the CL, whereas the inhibitory effect of ACTH is mediated through the placenta. The results indicate that these inhibitory effects of corticosterone or ACTH are eliminated if the CL has been exposed to enough placental hormones before day 15 of pregnancy. Journal of Endocrinology (1991) 129, 405–410

Opioid modulation of FSH, growth hormone and prolactin secretion in the prepuberal gilt

1992 ◽  
Vol 133 (1) ◽  
pp. 13-19 ◽  
Author(s):  
C. R. Barb ◽  
R. R. Kraeling ◽  
G. B. Rampacek
Keyword(s):  
Body Weight ◽  
Prolactin Secretion ◽  
Morphine Treatment ◽  
Endogenous Opioid Peptides ◽  
Endogenous Opioid ◽  
Gh Secretion ◽  
Age Related ◽  
Artificial Cerebrospinal Fluid ◽  
Serum Gh

ABSTRACT The role of endogenous opioid peptides (EOP) in modulating GH, prolactin (PRL) and FSH secretion was evaluated in prepuberal (P) gilts. In experiment I, P gilts received 1 (n = 2), 3 (n = 3) or 6 (n = 3) mg naloxone (NAL)/kg body weight i.v. Blood was collected every 15 min for 2 h prior to and 2 h after NAL and an additional 1 h after 100 μg gonadotrophinreleasing hormone (GnRH) i.v. In experiment II, P and mature (M) gilts were ovariectomized. Three weeks after ovariectomy, P and M gilts were injected twice a day for 10 days with either 0·85 mg progesterone (P4)/kg body weight or oil vehicle (V), resulting in the following groups: PP4 (n=11), PV (n = 10), MP4 (n=11) and MV (n=10). All gilts received 1 mg NAL/kg body weight on the last day of treatment. Blood samples were collected every 15 min for 4 h before and 2 h after NAL and an additional 1 h after 100μg GnRH i.v. In experiment III, six P and five M gilts were ovariectomized and surgically implanted with intracerebroventricular (i.c.v.) cannulae. Blood was collected every 15 min for 3 h before and 3 h after i.c.v. injection of 500 μg morphine in artificial cerebrospinal fluid (CSF) or 250 μl CSF. In experiment I, all doses of NAL failed to alter PRL secretion, while NAL increased (P<0·05) GH secretion in three out of eight gilts. However, NAL suppressed (P <0·05) FSH concentrations. In experiment II, NAL treatment increased (P<0·01) serum PRL concentrations and suppressed (P <0·05) FSH secretion in MP4 gilts. Serum PRL and FSH concentrations were unaltered by NAL in PV, PP4 and MV gilts. In experiment III, mean serum GH, PRL and FSH concentrations were unaffected by CSF injections. Morphine treatment evoked a rapid increase in serum GH and PRL concentrations in both P and M gilts. In contrast, morphine failed to influence FSH secretion in P gilts but did suppress FSH concentrations in M gilts. These data suggest that EOP receptors are functionally coupled to the GH and PRL secretory systems. There is an age-related change in EOP modulation of PRL secretion, while EOP modulation of FSH secretion is an age- and ovarian-dependent process. Journal of Endocrinology (1992) 133, 13–19

Feedback regulation by progesterone of stress-induced prolactin release in rats

1989 ◽  
Vol 120 (1) ◽  
pp. 37-43 ◽  
Author(s):  
R. P. Deis ◽  
E. Leguizamon ◽  
G. A. Jahn
Keyword(s):  
Prolactin Secretion ◽  
Female Rats ◽  
Male Rats ◽  
Serum Prolactin ◽  
Progesterone Concentration ◽  
Prolactin Release ◽  
Serum Progesterone ◽  
Progesterone Secretion ◽  
Male And Female Rats

ABSTRACT We have previously found that modifications to serum progesterone concentration have profound inhibitory effects on prolactin release in response to ether stress. The objective of the present study was to determine the effect of ether stress on progesterone secretion and the role of this steroid in ether-induced prolactin release. Serum progesterone concentration, 5 min after ether stress had been applied over a 2-min period, was consistently increased in male rats, in cyclic rats on the mornings of pro-oestrus and oestrus, and in androgenized rats in permanent oestrus. Ovariectomized androgenized rats showed the same response. Adrenalectomy of male and female rats abolished the progesterone increase induced by stress. Thus, the progesterone secreted by stressed rats is mostly of adrenal origin. In groups of male and pro-oestrous rats, circulating concentrations of prolactin and progesterone were measured from 5 to 60 min after stress. In both sexes the serum prolactin concentration was significantly increased at only 5 and 10 min after stress when compared with control values. In pro-oestrous rats the serum progesterone concentration was significantly higher than in controls at 5, 10 and 20 min after stress, whilst in male rats the concentration remained significantly higher at 30 min. Thirty minutes after the first stress, male and pro-oestrous rats were etherized for 2 min, and bled 5 min after removal from the ether container. In female rats this second stress produced only a slight but significant increase in serum prolactin concentrations, whereas in male rats prolactin concentrations did not increase. The second stress was still capable of significantly increasing circulating progesterone concentrations to levels similar to those obtained after the first stress in animals from all groups. Thus, an increased circulating progesterone concentration did not lead to regulation of further progesterone secretion. To find whether this type of response was due to a blocking effect of the previously released progesterone, animals were injected with the anti-progesterone RU 38486 (17β-hydroxy-11β-(4-dimethylaminophenyl)-17α-propinyl-oestra-4,9-dien-3-one) or with a specific antibody raised against progesterone. In both groups of treated rats the second stress induced a significant increase in serum prolactin and progesterone concentrations to give values similar to those obtained after the first stress. When the second stress was applied to female rats 60 min after the first the prolactin response was comparable to that obtained after the first exposure to ether. In conclusion, we have demonstrated that serum prolactin and progesterone concentrations are significantly increased after ether stress, and that the latter hormone exerts an inhibitory regulatory feedback on prolactin secretion. These results provide an important new insight into the role of progesterone in the regulation of prolactin release. Journal of Endocrinology (1989) 120, 37–43

Tryptophan-Niacin Metabolism in Rat with Puromycin Aminonucleoside-Induced Nephrosis

2006 ◽  
Vol 76 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Yukari Egashira ◽  
Shin Nagaki ◽  
Hiroo Sanada
Keyword(s):  
Body Weight ◽  
Urinary Excretion ◽  
Enzyme Activities ◽  
Treated Group ◽  
Control Group ◽  
Puromycin Aminonucleoside ◽  
Low Level ◽  
Key Enzyme

We investigated the change of tryptophan-niacin metabolism in rats with puromycin aminonucleoside PAN-induced nephrosis, the mechanisms responsible for their change of urinary excretion of nicotinamide and its metabolites, and the role of the kidney in tryptophan-niacin conversion. PAN-treated rats were intraperitoneally injected once with a 1.0% (w/v) solution of PAN at a dose of 100 mg/kg body weight. The collection of 24-hour urine was conducted 8 days after PAN injection. Daily urinary excretion of nicotinamide and its metabolites, liver and blood NAD, and key enzyme activities of tryptophan-niacin metabolism were determined. In PAN-treated rats, the sum of urinary excretion of nicotinamide and its metabolites was significantly lower compared with controls. The kidneyα-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD) activity in the PAN-treated group was significantly decreased by 50%, compared with the control group. Although kidney ACMSD activity was reduced, the conversion of tryptophan to niacin tended to be lower in the PAN-treated rats. A decrease in urinary excretion of niacin and the conversion of tryptophan to niacin in nephrotic rats may contribute to a low level of blood tryptophan. The role of kidney ACMSD activity may be minimal concerning tryptophan-niacin conversion under this experimental condition.

Questions on the role of biofilms for the adaptation of microorganisms to unfavorable environmental factors by the example of P. aeruginosa

2020 ◽  
Vol 99 (4) ◽  
pp. 379-383
Author(s):  
Vasily N. Afonyushkin ◽  
N. A. Donchenko ◽  
Ju. N. Kozlova ◽  
N. A. Davidova ◽  
V. Yu. Koptev ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Environmental Factors ◽  
Barrier Function ◽  
Infectious Agent ◽  
Antagonistic Activity ◽  
The Body ◽  
Main Function ◽  
Pathogenic Potential ◽  
The Face

Pseudomonas aeruginosa is a widely represented species of bacteria possessing of a pathogenic potential. This infectious agent is causing wound infections, fibrotic cystitis, fibrosing pneumonia, bacterial sepsis, etc. The microorganism is highly resistant to antiseptics, disinfectants, immune system responses of the body. The responses of a quorum sense of this kind of bacteria ensure the inclusion of many pathogenicity factors. The analysis of the scientific literature made it possible to formulate four questions concerning the role of biofilms for the adaptation of P. aeruginosa to adverse environmental factors: Is another person appears to be predominantly of a source an etiological agent or the source of P. aeruginosa infection in the environment? Does the formation of biofilms influence on the antibiotic resistance? How the antagonistic activity of microorganisms is realized in biofilm form? What is the main function of biofilms in the functioning of bacteria? A hypothesis has been put forward the effect of biofilms on the increase of antibiotic resistance of bacteria and, in particular, P. aeruginosa to be secondary in charcter. It is more likely a biofilmboth to fulfill the function of storing nutrients and provide topical competition in the face of food scarcity. In connection with the incompatibility of the molecular radii of most antibiotics and pores in biofilm, biofilm is doubtful to be capable of performing a barrier function for protecting against antibiotics. However, with respect to antibodies and immunocompetent cells, the barrier function is beyond doubt. The biofilm is more likely to fulfill the function of storing nutrients and providing topical competition in conditions of scarcity of food resources.

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