Temperature effects on serum prolactin concentrations and activity of dopaminergic neurons in the infundibulum/pituitary stalk of calves.
The effects of ambient temperature on serum concentrations of prolactin and neurochemical estimates of activity of dopaminergic neurons projecting to the infundibulum/pituitary stalk were investigated in Holstein bull calves. Accumulation of 3,4-dihydroxyphenylalanine (DOPA) in the infundibulum/pituitary stalk after intravenous injection of a decarboxylase inhibitor was used to estimate activity of these dopaminergic neurons. Increasing ambient temperature from 21 to 33 degrees C for 22 hr increased serum concentrations of prolactin and decreased activity of the dopaminergic neurons. Conversely, reducing ambient temperature from 22 degrees C to 11 degrees C decreased serum concentrations of prolactin and increased activity of these dopaminergic neurons. It is suggested that alterations in activity of dopaminergic neurons terminating in the infundibulum/pituitary stalk of bull calves may mediate acute temperature-induced changes in secretion of prolactin.
Tucker
H A
HA
Department of Animal Science, Michigan State University, East Lansing 48824.
Chapin
L T
LT
Lookingland
K J
KJ
Moore
K E
KE
Dahl
G E
GE
Evers
J M
JM
D000064:Acclimatization; D000818:Animals; D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D002417:Cattle; D004295:Dihydroxyphenylalanine / Q000378:metabolism; D004298:Dopamine / Q000097:blood / Q000502:physiology*; D006834:Hydrazines / Q000494:pharmacology; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000502:physiology*; D011388:Prolactin / Q000097:blood*; D013696:Temperature
D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D006834:Hydrazines; D004295:Dihydroxyphenylalanine; D011388:Prolactin; C004297:3-hydroxybenzylhydrazine; D004298:Dopamine