Pattern of Luteinizing Hormone Secretion During Delayed Implantation in the Spotted Skunk (Spilogale putorius latifrons)12

Since insufficient secretion of gonadotropins has been implicated as a possible cause of delayed implantation in mustelids the pattern of luteinizing hormone (LH) secretion and changes in plasma levels of this hormone during pregnancy in the western spotted skunk were studied. 30 pregnant and 17 nonpregnant sexually mature females were bled twice monthly by cardiac puncture beginning in the middle of the 7-month preimplantation period and continuing until just prior to nidation. The jugular vein of 7 pregnant and 4 nonpregnant skunks was cannulated prior to implantation and blood drawn every 2 hours until nidation. 3 additional pregnant animals were sampled at 2-hour intervals during middelay (January). LH levels were determined by double antibody radioimmunoassay. Peripheral plasma levels of LH in pregnant skunks were low at 120 days prior to nidation (4.9 ng/m1). Thereafter mean LH levels gradually increased until nidation at which time they fluctuated about a mean of 7.9 ng/m1. Plasma levels of LH in nonpregnant skunks were generally higher throughout the same period. The pattern of LH secretion in pregnant skunks did not appear to differ between mid preimplantation (January) and the week preceding nidation (late April) as determined by 2-hour serial samples. No surge in LH was observed prior to nidation although peak and basal levels of LH were somewhat higher than in January. The gradual rise in in LH secretion was paralleled by a similar rise in progesterone thus suggesting that LH might have a direct and/or indirect role in initiating resumption of full luteal function and embryonic development.(AUTHORS MODIFIED)