Serum luteinizing hormone, testosterone, prolactin and cortisol concentrations after PGF2 alpha in the boar

The effect of prostaglandin F2 alpha (PGF2 alpha) on serum luteinizing hormone (LH), testosterone (T), prolactin (PRL) and cortisol (CS) was studied in the boar. Indwelling cannulae were placed nonsurgically in the jugular vein of six 8 to 9 month-old boars weighing 130 to 160 kilograms. Twenty-four hr after cannulation, blood samples were collected every 30 min from 0630 to 1830 hours. Immediately after the second blood sample (0700 hr) three boars were injected intramuscularly (IM) with 20 mg PGF2 alpha and three boars were injected IM with saline (C). Serum concentrations of LH, T, PRL and CS were quantitated by radioimmunoassay. Serum LH and T concentrations were similar for the PGF2 alpha and C boars throughout the sampling period. In contrast, PRL and CS increased from basal concentrations (mean +/- SE) of 2.1 +/- .1 ng/ml and 24.0 +/- .9 ng/ml to 11.6 +/- .3 ng/ml and 86.9 +/- 9.8 ng/ml, respectively, within 30 min after PGF2 alpha injections and then decreased to control levels over the next 2.0 to 2.5 hours.