Effect of haloperidol on the synthesis of DNA in the pituitary gland of the rat

Lithium stimulates progenitor proliferation in cultured brain neurons

The number of neurons in the brain is controlled by production of new neurons and neuronal death. Neural progenitor proliferation in the developing and adult brain plays a prominent role in the production of new neurons. Here, we examined the effects of lithium, a mood-stabilizing drug, on neuronal proliferation in rat primary neuronal cultures. The incorporation of 5-bromo-2'-deoxyuridine (BrdU) into replicating DNA was used to label proliferating cells. BrdU incorporation was detected by immunocytochemistry in cerebellar granule cells prepared from postnatal rats and cerebral cortical cultures prepared from embryonic rats. Quantification of BrdU incorporation into cultures was performed by counting BrdU-positive cells and BrdU-coupled enzyme-linked immunosorbent assay. Both methods revealed that lithium increased BrdU incorporation in cerebellar granule cells and cerebral cortical cultures. Most BrdU-positive cells colocalized with nestin, a neuroblast cell marker, in cerebral cortical cultures. Blockade of DNA replication by cytosine arabinoside almost completely abolished BrdU incorporation, suggesting that lithium-induced BrdU incorporation was mainly due to enhanced DNA replication. Glutamate, glucocorticoids and haloperidol were found to markedly reduce neural progenitor proliferation in cerebellar granule cells. The presence of lithium prevented the loss of proliferation induced by these agents. Lithium-induced neural progenitor proliferation in vitro suggests that similar effects might occur in vivo and this action could also be related to its clinical efficacy. Cultured brain neurons may provide a valuable model for studying the molecular mechanisms underlying lithium-induced up-regulation of neural proliferation.

Regulation of pituitary DNA synthesis during different reproductive states in the female rat: role of estrogens and prolactin

We studied DNA synthesis in the rat adenohypophysis during the estrous cycle, pregnancy and lactation. During the estrous cycle, DNA synthesis was 3 times higher on the morning of estrus than on the other days. This peak was abolished completely by ovariectomy or pentobarbital, which also blocked the preovulatory surges of LH and prolactin. Methallibure , which blocked the LH but not the prolaction surge, had a partial effect on DNA synthesis. An acute and significant decrease in pituitary DNA synthesis occurred between days 0 (estrus) and 1 of pregnancy, followed by a less pronounced diminution until parturition. After delivery, DNA synthesis increased steeply on day 1 of lactation, returning to low values by day 3, under normal suckling conditions. Thelectomy , which blocked suckling-induced prolactin release, or antiestrogen treatment, which did not decrease prolactin secretion, diminished pituitary DNA synthesis on day 1 of lactation. Estrogen administration to intact or ovariectomized rats on days 9-11 of lactation stimulated (100%) DNA synthesis. Ovariectomy had no effect. In conclusion, in the different reproductive states studied, pituitary DNA synthesis is related to prolactin release in the presence of estrogens.