Neuroendocrine aspects of aging: experimental data.
Aging is characterized by changes in neuroendocrine/endocrine functions which are manifest in female reproductive physiology and less perceptible in other functions such as thyroid, adrenal or growth/metabolic functions. The contribution of each level of the axis - hypothalamus, adenohypophysis or peripheral tissues - is not clearly established. Functional impairments with age are recognized in the peripheral glands (gonad, thyroid, adrenal) as well as in the pituitary, but increasing evidence is accumulating for a marked contribution of the hypothalamus in the age-associated endocrine changes observed in animals and humans. In old rats, multineuronal dysfunctions are demonstrated in the hypothalamus, with a documented decline in the activity of the neurons producing dopamine and thyrotropin-releasing hormone, and to a lesser extent luteinizing hormone- and growth hormone-releasing hormones, and alterations in regulatory mechanisms of these neurons are disclosed. Moreover, impairments are observed in the processing - binding, accumulation and intracellular distribution - of hypothalamic hormones in the adenohypophysis of old rats. Taken together, these observations are supportive of the view that the neuroendocrine/endocrine changes appearing with age result from a complex balance of functional alterations occurring at each level - central and peripheral - of the axis.
Reymond
M J
MJ
Department of Internal Medicine, University Hospital, Lausanne, Switzerland.
Donda
A
A
Lemarchand-Béraud
T
T
D000311:Adrenal Glands / Q000502:physiology; D000375:Aging / Q000502:physiology*; D000818:Animals; D004702:Endocrine Glands / Q000502:physiology*; D006128:Growth; D051381:Rats; D012098:Reproduction; D013961:Thyroid Gland / Q000502:physiology