Neuronal responses in the brainstem and hypothalamic nuclei following insulin treatment during the late follicular phase in the ewe.
The aim of this study was to determine the neuronal responses following insulin administration during the late follicular phase. Intact ewes were given either saline or insulin (5 IU/kg, i.v.) at 35 h after progesterone withdrawal and killed 3 h later. There was a marked increase in the number of Fos-positive noradrenergic neurones in the caudal brainstem of insulin-treated ewes. In the hypothalamic paraventricular nucleus, insulin treatment increased the presence of Fos-positive corticotrophin-releasing hormone neurones (from 2% to 98%) and Fos-positive arginine vasopressin parvocellular neurones (from 2% to 46%). Interestingly, after insulin treatment, despite a general increase in Fos-positive neurones in the arcuate nucleus (ARC), there was a marked reduction (from 47% to 1%) in Fos-positive β-endorphin neurones. Similarly, colocalized Fos and oestradiol receptor (ER) α-positive neurones decreased in the ARC after insulin (from 7% to 3%). Conversely, in the ventromedial nucleus, ERα-positive neurones with Fos increased (from 7% to 22%) alongside a general increase in Fos-positive neurones. Overall, a complex system of neurones in brainstem and hypothalamus is activated following insulin administration during the late follicular phase.
Ghuman
S P S
SP
Reproduction Research Group, Department of Veterinary Clinical Science, University of Liverpool, Leahurst, Neston, Wirral, CH64 7TE, UK. ghuman_s@yahoo.co.in
Morris
R
R
Scherzer
J
J
Routly
J E
JE
Mobasheri
A
A
Smith
R F
RF
Dobson
H
H
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology / Q000187:drug effects; D001127:Arginine Vasopressin / Q000032:analysis; D001933:Brain Stem / Q000166:cytology* / Q000187:drug effects; D002452:Cell Count; D003346:Corticotropin-Releasing Hormone / Q000032:analysis; D047628:Estrogen Receptor alpha / Q000032:analysis; D005260:Female; D005498:Follicular Phase; D007031:Hypothalamus / Q000166:cytology* / Q000187:drug effects; D007328:Insulin / Q000494:pharmacology*; D009474:Neurons / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000187:drug effects; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis; D012756:Sheep / Q000502:physiology*; D001615:beta-Endorphin / Q000032:analysis
D047628:Estrogen Receptor alpha; D007328:Insulin; D016760:Proto-Oncogene Proteins c-fos; D001127:Arginine Vasopressin; D001615:beta-Endorphin; D003346:Corticotropin-Releasing Hormone