Effects of advancing age on hypothalamic neurotransmitter content and on basal and norepinephrine-stimulated LHRH release.
In order to elucidate possible mechanism(s) responsible for the age-related decline in LH secretion, basal and norepinephrine (NE)-stimulated LHRH release was measured from median eminence (ME) fragments of 4-, 11-, 18- and 27-month-old male F344 rats. Serum LH levels declined significantly between 11 and 18 months and were still lower at 27 months of age, while testosterone levels declined continuously between 4 and 27 months. Hypothalamic NE and dopamine (DA) content also declined significantly with age, while serotonin and 5-hydroxy-indoleacetic acid content increased with age. Despite the decline in serum LH levels with age, in vitro basal LHRH release increased gradually with age as did NE-stimulated LHRH release. These data suggest that the age-related reduction in LH secretion by the male rat is due to a reduction in hypothalamic NE metabolism and not to an inability of the LHRH neuron to respond to NE stimulation.
Steger
R W
RW
De Paolo
L V
LV
Shepherd
A M
AM
D000375:Aging; D000818:Animals; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D013268:Stimulation, Chemical; D013739:Testosterone / Q000097:blood
D018377:Neurotransmitter Agents; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D007986:Luteinizing Hormone; D009638:Norepinephrine