title: Neural systems mediating seasonal breeding in the ewe.
abstract: Seasonal reproduction in ewes is caused by a dramatic increase in response to oestradiol (E(2)) negative feedback during the nonbreeding (anoestrous) season. Considerable evidence supports the hypothesis that A15 dopaminergic neurones in the retrochiasmatic area (RCh) play a key role in these seasonal changes. These A15 neurones are stimulated by E(2) and inhibit gonadotrophin-releasing hormone (GnRH) secretion in anoestrus, but not the breeding season. Because A15 neurones do not contain oestrogen receptors-alpha (ER alpha), it is likely that E(2)-responsive afferents stimulate their activity when circulating E(2) levels increase during anoestrus. Retrograde tract tracing studies identified a limited set of ER alpha-containing afferents primarily found in four areas [ventromedial preoptic area, RCh, ventromedial and arcuate (ARC) nuclei]. Pharmacological and anatomical data are consistent with GABA- and glutamate-containing afferents controlling A15 activity in anoestrus, with E(2) inhibiting GABA and stimulating glutamate release at this time of year. Tract tracing demonstrated that A15 efferents project posteriorly to the median eminence and the ARC, suggesting possible direct actions on GnRH terminals or indirect actions via kisspeptin neurones in the ARC to inhibit GnRH in anoestrus. Identification of this neural circuitry sets the stage for the development of specific hypotheses for morphological or transmitter/receptor expression changes that would account for seasonal breeding in ewes.
authors.affiliation: Department of Physiology & Pharmacology, West Virginia University, Morgantown, WV, USA. bgoodman@hsc.wvu.edu
authors.forename: R L
authors.initials: RL
authors.lastname: Goodman
authors.forename: H T
authors.initials: HT
authors.lastname: Jansen
authors.forename: H J
authors.initials: HJ
authors.lastname: Billings
authors.forename: L M
authors.initials: LM
authors.lastname: Coolen
authors.forename: M N
authors.initials: MN
authors.lastname: Lehman
mesh_terms: D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism; D001947:Breeding; D004298:Dopamine / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism; D005260:Female; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D012098:Reproduction / Q000502:physiology*; D012621:Seasons; D012756:Sheep / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D004958:Estradiol; D005680:gamma-Aminobutyric Acid; D004298:Dopamine
references.citation: Endocrinology. 2000 Nov;141(11):4218-25
references.pmid: 11089556
references.citation: Endocrinology. 1977 Sep;101(3):818-24
references.pmid: 560960
references.citation: Biol Reprod. 1982 Oct;27(3):580-9
references.pmid: 6753958
references.citation: Endocrinology. 1980 Nov;107(5):1286-90
references.pmid: 7000489
references.citation: Endocrinology. 1989 Mar;124(3):1579-81
references.pmid: 2563684
references.citation: Biol Reprod. 2000 Nov;63(5):1352-7
references.pmid: 11058538
references.citation: Endocrinology. 2008 Jun;149(6):2762-72
references.pmid: 18325998
references.citation: J Neuroendocrinol. 1998 Jul;10(7):551-8
references.pmid: 9700682
references.citation: Endocrinology. 2010 Aug;151(8):3836-46
references.pmid: 20519368
references.citation: Endocrinology. 2003 Aug;144(8):3663-76
references.pmid: 12865349
references.citation: Histochemistry. 1990;93(3):327-33
references.pmid: 2312361
references.citation: Biol Reprod. 2002 Sep;67(3):829-36
references.pmid: 12193391
references.citation: J Endocrinol. 2005 Aug;186(2):397-409
references.pmid: 16079265
references.citation: Endocrinology. 1994 Apr;134(4):1905-14
references.pmid: 7907976
references.citation: J Chem Neuroanat. 2000 May;19(1):47-67
references.pmid: 10882837
references.citation: J Neurosci Methods. 1999 Sep 15;91(1-2):1-8
references.pmid: 10522819
references.citation: Neurosci Lett. 2006 Jul 3;401(3):225-30
references.pmid: 16621281
references.citation: Mol Cell Endocrinol. 2006 Jun 27;252(1-2):69-73
references.pmid: 16647195
references.citation: J Neuroendocrinol. 2008 Jun;20(6):732-42
references.pmid: 18601696
references.citation: Biol Reprod. 2003 Mar;68(3):846-52
references.pmid: 12604634
references.citation: Endocrinology. 1999 Dec;140(12):5929-36
references.pmid: 10579360
references.citation: Physiologist. 1980 Dec;23(6):29-38
references.pmid: 7208642
references.citation: Biol Reprod. 1997 Jun;56(6):1544-9
references.pmid: 9166708
references.citation: Neuroendocrinology. 1989 Jan;49(1):80-7
references.pmid: 2497396
references.citation: Cell Tissue Res. 1995 Sep;281(3):561-7
references.pmid: 7553775
references.citation: Biol Reprod. 1992 Jun;46(6):1130-5
references.pmid: 1391310
references.citation: Biol Reprod. 1991 Mar;44(3):476-82
references.pmid: 1673066
references.citation: Endocrinology. 1996 Oct;137(10):4443-50
references.pmid: 8828506
references.citation: J Neuroendocrinol. 1991 Aug 1;3(4):387-91
references.pmid: 19215481
references.citation: Biol Reprod. 1994 May;50(5):1168-77
references.pmid: 7912958
references.citation: Recent Prog Horm Res. 1984;40:185-232
references.pmid: 6385166
references.citation: J Comp Neurol. 2003 Oct 6;465(1):136-44
references.pmid: 12926021
references.citation: Endocrinology. 2004 Jun;145(6):2959-67
references.pmid: 14988383
references.citation: Mol Endocrinol. 2003 Jun;17(6):1039-53
references.pmid: 12624116
references.citation: Reprod Sci. 2007 Feb;14(2):101-16
references.pmid: 17636222
references.citation: Endocrinology. 2006 Oct;147(10):4843-51
references.pmid: 16857749
references.citation: Endocrinology. 1998 Apr;139(4):1508-16
references.pmid: 9528928
references.citation: Neuroendocrinology. 1993 Apr;57(4):751-9
references.pmid: 8367037
references.citation: Endocrinology. 1994 Apr;134(4):1806-11
references.pmid: 8137746
references.citation: Biol Reprod. 1986 Oct;35(3):562-71
references.pmid: 2878692
references.citation: Endocrinology. 1997 Jun;138(6):2585-95
references.pmid: 9165052
references.citation: J Reprod Fertil Suppl. 1995;49:285-96
references.pmid: 7623320
references.citation: Endocrinology. 1985 May;116(5):2054-61
references.pmid: 2859194
references.citation: J Endocrinol. 1983 Feb;96(2):181-93
references.pmid: 6827203
references.citation: Endocrinology. 2008 Nov;149(11):5770-82
references.pmid: 18617612
references.citation: Biol Reprod. 1985 May;32(4):779-87
references.pmid: 4005347
references.citation: Reprod Suppl. 2002;59:149-65
references.pmid: 12698979
references.citation: Biol Reprod. 1984 Mar;30(2):374-81
references.pmid: 6538445
references.citation: Endocrinology. 2000 Jan;141(1):190-6
references.pmid: 10614639
references.citation: Endocrinology. 2004 Sep;145(9):4264-7
references.pmid: 15178649
references.citation: Biol Reprod. 1994 Apr;50(4):965-76
references.pmid: 8199277
references.citation: Endocrinology. 1993 Aug;133(2):887-95
references.pmid: 8102098
references.citation: Endocrinology. 2009 Oct;150(10):4663-71
references.pmid: 19589862
references.citation: Endocrinology. 2007 Dec;148(12):5752-60
references.pmid: 17823266
references.citation: Biol Reprod. 1997 Mar;56(3):655-62
references.pmid: 9047010
references.citation: J Neuroendocrinol. 2001 Dec;13(12):1051-8
references.pmid: 11722701