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Response to selection for photoperiod responsiveness on the density and location of mature GnRH-releasing neurons.
- Source :
-
American journal of physiology. Regulatory, integrative and comparative physiology [Am J Physiol Regul Integr Comp Physiol] 2005 May; Vol. 288 (5), pp. R1226-36. Date of Electronic Publication: 2005 Jan 13. - Publication Year :
- 2005
-
Abstract
- Natural variation in neuroendocrine traits is poorly understood, despite the importance of variation in brain function and evolution. Most rodents in the temperate zones inhibit reproduction and other nonessential functions in short winter photoperiods, but some have little or no reproductive response. We tested whether genetic variability in reproductive seasonality is related to individual differences in the neuronal function of the gonadotropin-releasing hormone network, as assessed by the number and location of mature gonadotropin-releasing hormone-secreting neurons under inhibitory and excitatory photoperiods. The experiments used lines of Peromyscus leucopus previously developed by selection from a wild population. One line contained individuals reproductively inhibited by short photoperiod, and the other line contained individuals nonresponsive to short photoperiod. Expression of mature gonadotropin-releasing hormone (GnRH) immunoreactivity in the brain was detected using SMI-41 antibody in the single-labeled avidin-biotin-peroxidase-complex method. Nonresponsive mice had 50% more immunoreactive GnRH neurons than reproductively inhibited mice in both short- and long-day photoperiods. The greatest differences were in the anterior hypothalamus and preoptic areas. In contrast, we detected no significant within-lines differences in the number or location of immunoreactive GnRH neurons between photoperiod treatments. Our data indicate that high levels of genetic variation in a single wild population for a specific neuronal trait are related to phenotypic variation in a life history trait, i.e., winter reproduction. Variation in GnRH neuronal activity may underlie some of the natural reproductive and life history variation observed in wild populations of P. leucopus. Similar genetic variation in neuronal traits may be present in humans and other species.
- Subjects :
- Animals
Cell Count
Female
Genetic Variation
Male
Neurons cytology
Peromyscus anatomy & histology
Peromyscus genetics
Peromyscus metabolism
Reproduction genetics
Reproduction physiology
Brain cytology
Gene Expression Regulation physiology
Gonadotropin-Releasing Hormone biosynthesis
Neurons metabolism
Peromyscus physiology
Photoperiod
Subjects
Details
- Language :
- English
- ISSN :
- 0363-6119
- Volume :
- 288
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- American journal of physiology. Regulatory, integrative and comparative physiology
- Publication Type :
- Academic Journal
- Accession number :
- 15650126
- Full Text :
- https://doi.org/10.1152/ajpregu.00562.2004