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Biomedical subjects

M Leon

Publications and source records attributed to M Leon.

At least 199 records · Page 11Linked to original sources
PubMed1973

Maternal behavior in the rat: facilitation through gonadectomy.

Virgin rats were ovariectomized and tested for induction of maternal behavior by being housed with neonatal young. A postoperative interval of 8 weeks yielded an average latency for the onset of maternal behavior significantly lower than that for intact controls or for virgin females ovariectomized 4 weeks before testing. Replacement of estrogen in the group ovariectomized for 8 weeks or injection of the estrogen antagonist ethamoxytriphetol (MER-25) in the group ovariectomized for 4 weeks changed the average latencies accordingly. Parallel results were obtained for males that were castrated 4 or 8 weeks before testing. It is concluded (i) that maternal behavior is under gonadal control and that this control is normally inhibitory; and (ii) that only after long-term removal of the gonads, resulting presumably in the complete clearance of estrogen and testosterone, is the maternal mediating system finally released from steroid suppression.

Animals↗
PubMed1969

Prolactin in the postpartum rat: synthesis and release in the absence of suckling stimulation.

Postpartum female rats deprived of suckling stimulation while being kept continuously with pups nonetheless suspended ovarian cyclicity for an average of 16 days and responded to uterine trauma by forming deciduomata. These results show that the extramammary stimulation afforded by young is alone capable of sustaining prolactin output from the adenohypophysis of the postpartum rat.

Animals↗
PubMedDate not supplied

Low levels of calpain activity in Chiroptera brain: implications for mechanisms of aging.

Calcium-dependent neutral proteases ("calpains") have been implicated in degenerative processes in muscles and neurons, suggesting that they might also play a role in age-related brain pathologies and perhaps in brain aging itself. Because Chiroptera exhibit an unusual maximum life span, relative to other mammalian orders, we investigated the activity of these enzymes in the brain of two species of bats. As in other mammals, brain calpain degrades many proteins associated with the cell cytoskeleton. However, enzyme activity is 5-7 fold lower in bat's brain than in a similar-sized mammal, such as the mouse. Moreover, the maximal life span of bats predicted from the equation relating calpain activity and maximal life span across a wide range of mammals is close to the observed values. These results strengthen the hypothesis that calpain activity is somehow linked to the rate at which brains age.

Aging↗