Catecholamine levels and turnover during aging in brain regions of male C57BL/6J mice

Increased dopamine synthesis in aging substantia nigra neurons

“…(27) for further details]. These data demonstrate that the previously reported maintenance of DA concentrations in C57BL mice with aging (3,21,28) may have occurred upon a background of extensive neuronal loss.…”

“…Hence, the versus 22.2 -+ 1.6 for saline and MPTP mice, respectively). Mean compensatory increase in DA turnover and likely synthesis by an TH somal cytoplasmic optical densities were 3.6-or 2-fold above average remaining neuron appears to explain the unchanged valmean background values for the 8-week-old and saline-treated ues throughout life found by others (3,21,28). We have no data control mice, respectively, to determine whether the increase would continue for more extenThe TH cytoplasmic optical density above background optical sive neuronal loss.…”

Effects of Human Placental Extract on Brain Monoamines and Monoamine Oxidase Activity in Rats.

“…Numerous studies have shown that the levels of DA and NE decrease with age in the brain of rats (Histchorn et al 1982;Estes and Simpkine 1984) , mice (Osterburg et al 1981), rhesus monkey (Oray 1975) and human (Robinson 1975). TJ-980, a mixture of nine Japanese herbal drugs which is found to possess a possible anti-aging effect, elevated the NE and attenuated the 5-HT level in the hypothalamus of aged rats (Hiramatsu et al 1988).…”

The Increase of Anterior Pituitary Dopamine in Aging C57BL/6J Female Mice Is Caused by Ovarian Steroids, Not Intrinsic Pituitary Aging

“…However, pitu itary DA levels altered by pharmacologic means can vary widely without relation to circulating PRL [10]. Aging male mice have 75% increases of pituitary DA [37] without changes in plasma PRL [15]: more striking examples are seen in female mice (see Results).Ovarian steroids also influence the regulation of PRL secretion by DA. Previous studies show' that treatment of rodents with moderate doses of estradiol (E2) for 1 -3 weeks increases PRL secretion [6,28], and that prolonged treat ment will induce PRL-secreting pituitary tumors (lactotroph adenomas) [12,20, 50].…”

“…We conclude that the age-correlated increase in pituitary DA is primarily dependent upon the effectively enhanced estrogenic stimulation concomitant with reproductive senescence, rather than upon intrinsic pituitary aging or irreversible effects from exposure to E2 over a lifetime of estrous cycles. Dopamine (DA) levels in the anterior pituitary increase 75-300% during aging in male [37] and female [2,9] rodents. This increase, the largest reported neurochemical change of aging [42], is puzzling because DA is strongly implicated as an inhibitor of prolactin (PRL) secretion by the pituitary, yet circulating PRL and pituitary DA both increase with age in rats [9,26].…”