title: Photoperiodic time measurement is maintained in undernourished lambs with delayed puberty.
abstract: Beginning at 42 weeks of age undernourished females that had been maintained outdoors were exposed to long days (15L:9D) or short days (9L:15D). After 6 weeks, both groups were placed on short days, and ad-libitum feeding was begun. Rapid 'catch-up' growth occurred similarly in both groups. However, the response to oestradiol negative feedback regulation of LH secretion differed greatly. Short-day lambs remained hyperresponsive to oestradiol inhibition, and circulating LH remained low, a condition that typifies immaturity of the system governing LH secretion. In the females exposed to the long-day-short-day sequence, circulating LH began to increase 10 weeks after the end of long days; this change is characteristic of the neuroendocrine alteration that occurs during puberty. These findings indicate that the growth-retarded lamb can differentiate long days from short days, and can therefore continue to accumulate photoperiod information during prolonged periods of undernutrition.
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D008027:Light; D007986:Luteinizing Hormone / Q000097:blood; D009748:Nutrition Disorders / Q000097:blood*; D012741:Sexual Maturation; D012756:Sheep; D013997:Time Factors
chemical_list: D004958:Estradiol; D007986:Luteinizing Hormone