1. Department of Biology, School of Education, Waseda University, Nishiwaseda, Tokyo 169-50, Japan.
2. Department of Physiology, Nara Medical University, Kashihara 634, Japan.
3. Research Development Corporation, Riken, Wako 351 -01, Japan.
4. Department of Pharmacology, Nippon Medical School, Tokyo 1 13, Japan.
5. Institute of Endocrinology, Gunma University, Maebashi 371, Japan.
6. Gunma Prefectural College of Health Science, Maebashi 371, Japan.