PDYN
Proenkephalin-B precursor (Beta-neoendorphin-dynorphin) (Preprodynorphin) [Contains: Alpha-neoendorphin; Beta-neoendorphin; Big dynorphin (Big Dyn); Dynorphin A(1-17) (Dyn-A17) (Dynorphin A); Dynorphin A(1-13); Dynorphin A(1-8); Leu-enkephalin; Rimorphin (Dynorphin B) (Dyn-B) (Dynorphin B(1-13)); Leumorphin (Dynorphin B-29)]
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The neuropeptides kisspeptin, neurokinin B, and dynorphin A (collectively abbreviated as KNDy) are, respectively, encoded by KiSS-1, NKB, and PDYN and are coexpressed by neurons of the hypothalamic arcuate nucleus (ARC). Here, using quantitative real-time PCR, we examined age-related changes in the expression of genes encoding KNDy and associated receptors G protein-coupled receptor 54 (encoded by GPR54), neurokinin 3 receptor (encoded by NK3), and kappa-opioid receptor (encoded by KOR), in the female rhesus macaque ARC-median eminence (ARC-ME). Expression of KiSS-1 and NKB was highly elevated in old perimenopausal compared with young or middle-aged premenopausal animals. To test whether these age-related changes could be attributed to perimenopausal loss of sex steroids, we then examined KNDy, GPR54, NK3, and KOR expression changes in response to ovariectomy (OVX) and exposure to 17beta-estradiol (E(2)). Short-term (7 months) OVX (with or without 1 month of estrogen replacement) failed to modulate the expression of any of the KNDy-related genes. In contrast, long-term ( approximately 4 yr) OVX significantly increased KiSS-1 and NKB expression, and this was reversed by E(2) administration. Finally, we examined the expression of KNDy-related genes in young adult females during the early follicular, late follicular, or midluteal phases of their menstrual cycle but found no difference. Together, the results suggest that short-term alterations in circulating E(2) levels, such as those occurring during the menstrual cycle, may have little effect on the ARC-ME expression of KNDy and associated receptors. Nevertheless, they clearly demonstrate that loss of ovarian steroid negative feedback that occurs during perimenopause plays a major role in modulating the activity of KNDy circuits of the aging primate ARC-ME.
MeSH Terms
- Age Factors
- Aging
- Animals
- Arcuate Nucleus of Hypothalamus
- Enkephalins
- Estradiol
- Female
- Gene Expression
- Genes, Tumor Suppressor
- Macaca mulatta
- Median Eminence
- Neurokinin B
- Ovariectomy
- Protein Precursors
- Receptors, G-Protein-Coupled
- Time Factors
An in situ hybridization method was used to estimate the proenkephalin (PENK) and prodynorphin (PDYN) mRNA levels in the brain of epileptic 6-month-old WAG/Rij rats in comparison with non-epileptic: 3-month-old WAG/Rij rats, 3-month-old ACI rats and 6-month-old ACI rats. The epileptic rats had a significantly higher level of PENK mRNA in the striatum as compared to non-epileptic controls. The PDYN mRNA level was significantly elevated only in the hippocampus of epileptic rats, whereas age- or strain-related changes in the striatal and cortical PDYN mRNA levels were found in both epileptic and non-epileptic rats. The changes in the biosynthetic activity of endogenous opioid peptide systems may be important for the occurrence of epileptic discharges in these animals.
MeSH Terms
- Aging
- Animals
- Brain
- Cerebral Cortex
- Corpus Striatum
- Enkephalins
- Epilepsy, Absence
- Hippocampus
- In Situ Hybridization
- Male
- Protein Precursors
- RNA, Messenger
- Rats