title: Enlarging effects of estradiol on the nuclear volume of neurons in the hypothalamus during aging.
abstract: Neuronal nuclear volumes (NNVs) were measured in the medial preoptic nucleus (MPN), anterior hypothalamic area (AHA) and arcuate nucleus (ARN) of young adult, middle-aged, and old rats of both sexes. The NNVs in the darkly stained sexual-dimorphic nucleus of the preoptic area (SDN-POA) and the lighter staining surrounding area (non-SDN-POA) within the MPN were measured separately. Intact young and middle-aged female rats had larger NNVs than those of the males in SDN-POA, non-SDN-POA and AHA but not in ARN. During aging, only intact old female rats manifested significant NNV shrinkage in all the measured areas. Long-term treatment with estradiol benzoate (EB) caused a significant enlargement of the NNVs in non-SDN-POA and ARN of middle-aged and old male rats as well as the NNVs in SDN-POA, non-SDN-POA and ARN of old female rats. The enlarging effect of EB on NNVs in both SDN-POA and non-SDN-POA of female rats could be prevented by ovariectomy. Furthermore, NNVs in SDN-POA and non-SDN-POA of ovariectomized female rats were even smaller than those of the age-matched intact female rats. These results indicate that: (1) the NNVs of MPN and ARN in male and female rats were enlarged after long-term exposure of physiological dose of estradiol; (2) the enlarging effects of EB on NNV in MPN can explain why the NNV of intact female rats is larger than that of males, and (3) during aging, the sex-specific shrinkage of NNVs in MPN, AHA and ARN of female rats may be due to an intrinsic aging process rather than long-term effects of EB.
authors.affiliation: Department of Physiology, Kaohsiung Medical College, Taiwan, ROC. m685003@cc.kmc.edu.tw
authors.forename: C
authors.initials: C
authors.lastname: Hsu
authors.forename: S L
authors.initials: SL
authors.lastname: Yang
authors.forename: Y L
authors.initials: YL
authors.lastname: Hsieh
authors.forename: S I
authors.initials: SI
authors.lastname: Lue
authors.forename: H K
authors.initials: HK
authors.lastname: Hsu
authors.forename: M T
authors.initials: MT
authors.lastname: Peng
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D007025:Anterior Hypothalamic Nucleus / Q000166:cytology; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology; D002467:Cell Nucleus / Q000187:drug effects / Q000648:ultrastructure; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007031:Hypothalamus / Q000166:cytology* / Q000187:drug effects*; D008297:Male; D009474:Neurons / Q000187:drug effects* / Q000648:ultrastructure*; D011301:Preoptic Area / Q000166:cytology; D051381:Rats; D011919:Rats, Inbred Strains; D012727:Sex Characteristics; D013997:Time Factors
chemical_list: D004958:Estradiol