Bm. Alexander et al., SEASONAL EFFECTS OF ANTIHISTAMINE ON MEAN SERUM CONCENTRATIONS OF LUTEINIZING-HORMONE, GROWTH-HORMONE AND PROLACTIN IN OVARIECTOMIZED EWES, Animal reproduction science, 37(1), 1994, pp. 15-24
Ovariectomized ewes (n = 5) were treated with a histamine H-1-receptor
antagonist, diphenhydramine, once each month to determine if: (1) his
tamine affects serum concentrations of luteinizing hormone (LH), growt
h hormone (GH) and prolactin (PRL) during the breeding and anestrous s
easons and (2) if histamine regulates the release of pituitary hormone
s through common or discrete mechanisms. Effects of diphenhydramine (2
00 mg) on serum concentrations of LH, GH and PRL were analyzed during
the breeding season, anestrous season and periods of transition into,
or out of, the breeding season. Treatment suppressed (P < 0.05) serum
concentrations of LH (by 0.81 +/- 0.25 ng ml-1) during the breeding se
ason. Consistent effects were not noted during the anestrous season or
periods of transition. Diphenhydramine suppressed (P < 0.05) serum co
ncentrations of GH (by 1.11 +/- 0.45 ng ml-1) during the anestrous sea
son, but had no effect during the breeding season. Serum concentration
s of PRL were not affected (P > 0.05) by diphenhydramine. The possibil
ity that histamine may function as a general modulator of overall hypo
thalamic function is unlikely because diphenhydramine differentially a
ffected release of LH, GH and PRL. The absence of consistent effects o
f diphenhydramine on secretion of LH throughout the year do not suppor
t the premise that histamine is a direct modulator of release of gonad
otropin-releasing hormone.