Stuber D C, Johnson C L, Green C A, McLaren D G, Bahr J M, Easter R A
Department of Animal Sciences, University of Illinois, Urbana 61801.
Domest Anim Endocrinol. 1990 Jul;7(3):291-7. doi: 10.1016/0739-7240(90)90035-x.
Our objective was to examine the ability of thyroid releasing hormone (TRH) to stimulate not only the release of the thyroid hormones, but also prolactin (PRL) in the female pig. An experiment was conducted to determine the effect of dose and route of administration of TRH on the concentration of PRL and thyroxine (T4) in cyclic gilts. Six gilts were injected with 0, 5, 25, 125, and 625 micrograms TRH and fed 0, 5, 2.5, 12.5 and 62.5 mg TRH. Gilts received TRH once daily. During the 10-day treatment period, route of TRH administration alternated between i.v. injection and feeding. The dose of TRH progressed from the lowest to the highest. Blood samples were taken prior to TRH injection and thereafter at 15-min intervals for 3 hr. Sampling continued for an additional 3 hr at 30-min intervals when TRH was fed. Concentrations of PRL and T4 were determined by radioimmunoassay. Intravenous injection of gilts with 125 and 625 micrograms TRH resulted in an increase in PRL from 0 to 15 min (P less than .05). All doses of TRH given i.v. elevated T4 over a 2-hr period (P less than .01). TRH failed to increase PRL when TRH was fed (P greater than .5). The feeding of 62.5 mg TRH elevated T4 from 0 to 6 hr (P less than .01). Thus, TRH injection increased PRL rapidly and T4 gradually. When TRH was fed, only a gradual elevation in T4 was observed. We conclude that TRH can elicit the release of both PRL and T4 in the cyclic gilt, but magnitude and duration of the PRL and T4 response depends on the dose and route of TRH administration.
我们的目标是研究促甲状腺激素释放激素（TRH）不仅刺激甲状腺激素释放，还刺激雌性猪催乳素（PRL）释放的能力。进行了一项实验，以确定TRH的剂量和给药途径对发情后备母猪PRL和甲状腺素（T4）浓度的影响。给6头后备母猪分别注射0、5、25、125和625微克TRH，并投喂0、5、2.5、12.5和62.5毫克TRH。后备母猪每天接受一次TRH。在10天的治疗期内，TRH的给药途径在静脉注射和投喂之间交替。TRH的剂量从最低逐渐增加到最高。在注射TRH之前采集血样，此后每隔15分钟采集一次，持续3小时。当投喂TRH时，以30分钟的间隔再持续采集3小时血样。通过放射免疫测定法测定PRL和T4的浓度。给后备母猪静脉注射125和625微克TRH导致PRL在0至15分钟内升高（P<0.05）。静脉注射所有剂量的TRH在2小时内使T4升高（P<0.01）。当投喂TRH时，TRH未能增加PRL（P>0.5）。投喂62.5毫克TRH使T4在0至6小时内升高（P<0.01）。因此，注射TRH可迅速增加PRL并逐渐增加T4。当投喂TRH时，仅观察到T4逐渐升高。我们得出结论，TRH可引发发情后备母猪PRL和T4的释放，但PRL和T4反应的幅度和持续时间取决于TRH的剂量和给药途径。
