Environmental, age, and sex effects on cotton rat (Sigmodon hispidus) hematology.

We determined the effects of sex, age, and environment (inbred, captive-wild, and wild animals) on selected blood parameters of the cotton rat (Sigmodon hispidus) in central Oklahoma (USA) from 1990 to 1994. Male and female cotton rats had similar blood profiles. Age-related differences were confined to differential white blood cell counts where adults possessed greater numbers of neutrophils and lower numbers of lymphocytes compared to juveniles.

Impairment of glucose tolerance in yellow (Avy/A) (BALB/c X VY) F-1 hybrid mice by hyperglycemic peptide(s) from human pituitary glands.

A fraction of human pituitary extract containing low molecular weight peptide(s) was found to impair glucose tolerance in obese yellow (Avy/A) (BALB/c X VY) F-1 hybrid female mice. In these mice, purified human GH was not hyperglycemic. Glucose tolerance of untreated yellow mice was somewhat less impaired than that of untreated ob/ob mice, and priming with dexamethasone was not required to elicit impairment of glucose tolerance.

Absence of lipolytic activity from purified human growth hormone in cultured 3T3-L1 adipocytes.

Although standard preparations of growth hormone activated hormone-sensitive lipase in differentiated 3T3-L1 adipocytes, more highly purified preparations of human and bovine hormones were not lipolytic in this system. We found that the standard preparations were contaminated with a lipolytic substance which was removed during purification of the growth hormone. The purified growth hormone likewise did not stimulate lipolysis in adipose tissue from fasted rats.