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Biomedical subjects

P Poindron

Publications and source records attributed to P Poindron.

At least 127 records · Page 7Linked to original sources
PubMed1983

Vaginal stimulation: an important determinant of maternal bonding in sheep.

The immediate induction of the full complement of maternal behavior in nonpregnant ewes primed with estrogen and progesterone has been obtained after 5 minutes of vaginal-cervical stimulation. A similar period of such stimulation given to recently parturient ewes, after the development of selective bonding to their own lambs, reversed their rejection behavior of alien lambs and produced a state of plasticity in maternal behavior, such that ewes receiving vaginal stimulation would accept and adopt alien lambs. These findings implicate vaginal-cervical stimulation as playing a role in the onset of maternal behavior.

Animals↗
PubMed1983

Attraction and repulsion by amniotic fluids and their olfactory control in the ewe around parturition.

The reaction of ewes towards amniotic fluids was studied in intact multiparous ewes in various physiological states (oestrus, luteal phase, mid-pregnancy and around parturition), using a test of preference for food associated or not with the presence of amniotic fluids in the food. Fluids were collected on alien newborn lambs. Results indicate that ewes are strongly repelled by amniotic fluid at all of the times tested except for a short period around parturition. Immediately before expulsion of the foetus ewes become strongly attracted by amniotic fluids. This attraction persists just after parturition, but fades within 4 hours in most animals. This attraction-repulsion behavior appears to rely heavily on olfactory cues. Ewes made anosmic with zinc sulphate do not show repulsion or attraction towards amniotic fluids at any of the physiological states studied. These results are discussed in the light of our knowledge about the factors controlling the onset of maternal behavior in the ewe (hormones and genital stimulation).

Amniotic Fluid↗
PubMed1980

Importance of the characteristics of the young in the manifestation and establishment of maternal behaviour in sheep.

The role played by the lamb in the regulation of maternal behaviour of the ewe around parturition was investigated in three experiments. In the first, the spontaneous manifestation of that behaviour was observed in parturient ewes when their lambs were swapped with either newborn or 12 to 24-hr old alien lambs. The ewes were undisturbed, or only slightly so, when their lambs were exchanged for alien newborn. In contrast, very obvious and significant differences were observed when swapping involved 12 to 24-hr old lambs. In the second experiment, ewes totally separated from their lambs at birth and for 12 hrs accepted a newborn alien lamb more readily than their own 12-hr old lamb at the time of reunion. In the third experiment, ewes were maintained in partial contact with their lambs for 12 hrs and maternal behaviour was tested at that time. The ewes remained maternal up to the time of testing only if they could smell their lambs. It was concluded that some characteristics of the newborn lamb are necessary for the development of adequate maternal behaviour.

Animals↗
PubMed1980

Lack of association between the elevation of adenosine 3',5'-cyclic monophosphate and the potentiation of the interferon-induced antiviral state by noradrenaline in normal and tumoral rat cells.

Rat interferon (IF) induced a moderate and persistent elevation of adenosine 3',5'-cyclic monophosphate (cAMP) after 6 h of contact with rat embryo fibroblasts (REFs), whereas in rat glial tumoral c6 cells IF did not enhance cAMP. Noradrenaline potentiated the antiviral state of REFs treated for 2 h or more with IF and increased cAMP in these cells, but it did not potentiate the IF-induced antiviral state of C6 cells. However, as the control cells, IF-treated C6 cells responded to catecholamines by a 100-fold or more increase in cAMP. This suggested that cAMP was not primarily involved in the establishment of the antiviral state.

Animals↗
PubMed1979

[Origin and formation of different types of vacuoles induced by the multiplication of the alphavirus Sindbis virus in various cell systems].

Spherule-containing vacuoles and nucleocapsid-bearing vacuoles (cytopathic vacuoles types 1 and 2 respectively of Grimley et al. 1968) induced by Alphavirus Sindbis were studied in brains from newborn mice, chicken embryo fibroblasts, and two lines of tumoral glial cells from muridae. Endoplasmic reticulum (ER) elements and finely granular electron-dense material also seen in contact with nucleocapsids seemed to be involved in the formation of the classical single-membrane spherule-containing vacuoles. A second type of spherule-containing vacuoles were characterized by their double membrane and an amorphous electron-dense content and were probably derived from mitochondria. Nucleocapsid-bearing vacuoles were formed from modified ER elements and seemed to be linked to excessive synthesis of viral material. Such ER alterations were not observed in RG6 cells. In these cells, there were only spherule-containing vacuoles, while nucleocapsids were seen associated with the cytoplasmic membrane only.

Animals↗