PMID- 19114045
OWN - NLM
STAT- MEDLINE
DCOM- 20090929
LR  - 20131121
IS  - 1095-6840 (Electronic)
IS  - 0016-6480 (Linking)
VI  - 163
IP  - 1-2
DP  - 2009 Sep 1
TI  - Dopamine-melatonin neurons in the avian hypothalamus and their role as 
      photoperiodic clocks.
PG  - 123-7
LID - 10.1016/j.ygcen.2008.11.030 [doi]
AB  - A timing mechanism in the brain governs reproduction in seasonally breeding 
      temperate zone birds by triggering gonad development in response to long days in 
      the spring. The neural mechanism(s) responsible for the timing and induction of 
      reproductive activity by this clock are unknown. Utilizing in situ hybridization, 
      immunocytochemistry and reverse transcriptase-polymerase chain reaction 
      techniques, a group of dopamine (DA) neurons in the premammillary nucleus (PMM) 
      of the caudal turkey hypothalamus that synthesize and colocalize both DA and 
      melatonin (MEL) were identified. In addition, these neurons are found to express 
      clock genes and the circadian photoreceptor melanopsin. DA-MEL neurons reach 
      threshold activation (c-fos expression) when a light pulse is given during the 
      photosensitive phase. This is associated with increases in the number of 
      gonadotropin releasing hormone-I (GnRH-I) neurones activated, as well as an 
      up-regulation of GnRH-I mRNA expression. The expression of tyrosine hydroxylase 
      (TH; the rate limiting enzyme in DA biosynthesis) and tryptophan hydroxylase 1, 
      (TPH1; the first enzyme in MEL biosynthesis) and consequently DAergic-MELergic 
      activities are associated with the daily light-dark cycle. TPH1 mRNA expression 
      shows low levels during the light phase and high levels during the dark phase of 
      the light/dark illumination cycle and is 180 degrees out of phase with the rhythm 
      of TH mRNA expression. Hypothalamic DA-MEL neurons may constitute a critical 
      cellular process involved in the generation and expression of seasonal 
      reproductive rhythms and suggests a previously undescribed mechanism(s) by which 
      light signals gain access to neural targets.
FAU - El Halawani, Mohamed E
AU  - El Halawani ME
AD  - Department of Animal Science, University of Minnesota, 495 Animal 
      Science/Veterinary Medicine, 1988 Fitch Avenue, St. Paul, MN 55108, USA. 
      elhal001@tc.umn.edu
FAU - Kang, Seong W
AU  - Kang SW
FAU - Leclerc, Benoit
AU  - Leclerc B
FAU - Kosonsiriluk, Sunantha
AU  - Kosonsiriluk S
FAU - Chaiseha, Yupaporn
AU  - Chaiseha Y
LA  - eng
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
DEP - 20081211
PL  - United States
TA  - Gen Comp Endocrinol
JT  - General and comparative endocrinology
JID - 0370735
RN  - 33515-09-2 (Gonadotropin-Releasing Hormone)
RN  - EC 1.14.16.2 (Tyrosine 3-Monooxygenase)
RN  - EC 1.14.16.4 (Tryptophan Hydroxylase)
RN  - JL5DK93RCL (Melatonin)
RN  - VTD58H1Z2X (Dopamine)
SB  - IM
MH  - Animals
MH  - Biological Clocks/*physiology
MH  - Dopamine/*metabolism
MH  - Female
MH  - Gonadotropin-Releasing Hormone/metabolism
MH  - Hypothalamus/*metabolism
MH  - Immunohistochemistry
MH  - In Situ Hybridization
MH  - Light
MH  - Melatonin/*metabolism
MH  - Neurons/*metabolism/radiation effects
MH  - *Photoperiod
MH  - Reverse Transcriptase Polymerase Chain Reaction
MH  - Tryptophan Hydroxylase/genetics
MH  - Turkeys/*physiology
MH  - Tyrosine 3-Monooxygenase/genetics
EDAT- 2008/12/31 09:00
MHDA- 2009/09/30 06:00
CRDT- 2008/12/31 09:00
PHST- 2008/10/24 00:00 [received]
PHST- 2008/11/26 00:00 [revised]
PHST- 2008/11/27 00:00 [accepted]
PHST- 2008/12/31 09:00 [entrez]
PHST- 2008/12/31 09:00 [pubmed]
PHST- 2009/09/30 06:00 [medline]
AID - S0016-6480(08)00429-2 [pii]
AID - 10.1016/j.ygcen.2008.11.030 [doi]
PST - ppublish
SO  - Gen Comp Endocrinol. 2009 Sep 1;163(1-2):123-7. doi: 10.1016/j.ygcen.2008.11.030. 
      Epub 2008 Dec 11.