Differences in prolactin levels between three alternative male reproductive tactics in striped mice (Rhabdomys pumilio)

In male fishes, birds and mammals, increased prolactin secretion is thought to play a role in species showing paternal behaviours. This hypothesis was investigated in the striped mouse (Rhabdomys pumilio). This paper compares serum prolactin levels in 71 free-living male striped mice following three different reproductive tactics: (i) paternal group-living breeders, (ii) alloparental philopatric group-living males, and (iii) roaming non-paternal solitary males. Prolactin levels of breeding males were significantly higher than that of roamers. Alloparental philopatric males had low prolactin levels, which concur with studies of cooperatively breeding mammals, but contrasts with studies of cooperatively breeding birds. Both breeding males and females showed a decrease in prolactin levels after the breeding season, but not alloparental philopatric males. Prolactin levels were correlated with neither corticosterone levels nor age. These results are in agreement with the hypothesis that prolactin is one proximate mechanism of male reproductive tactics, possibly regulating differences in male parental care

Morphology of the lactotropes and somatotropes of man and rhesus monkeys

Histologic sections of the adenohypophyses of humans and rhesus monkeys were examined by differential staining methods and by an immunofluorescent procedure. In addition, the concentrations of prolactin and growth hormone (GH) in the adenohypophyses of the monkeys were estimated by disc electrophoresis and densitometry, and cell counts were performed on differentially- stained histologic sections. All of the glands examined had numerous somatotropes, which stained with orange G, and the same cells showed affinity for the fluorescent immune serum to hGH. The glands of the pregnant and postpartum women and of all the adult monkeys (lactating or nonlactating) contained prominent erythrosinophils (lactotropes) and these bound the fluorescent antiserum to ovine prolactin. The erythrosinophils did not react with the fluorescent antiserum to hGH and the orangeophils did not localize the fluorescent immune serum to ovine prolactin. The lactotropes were particularly numerous and hypertrophied in the lactating monkeys and in the pregnant and postpartum women. In the hypophyses of the adult "control" humans (i.e. neither pregnant nor postpartum) and of the infant monkeys, erythrosinophils were poorly discernible or not detectable with differential staining. However, all of these showed brightly fluorescent lactotropes with immune serum to ovine prolactin. The fluorescent lactotropes in the "control" human hypophyses were small and sparse. Those of the infant monkey glands were small but numerous. The assays of prolactin and GH concentrations in monkey glands disclosed that all adults had comparable GH levels. The infant glands had a higher GH concentration than those of adults. The prolactin concentration in the infant glands was low and about the same as that in adult males. The adenohypophyses of adult females had a slightly higher prolactin level than those of either adult males or infants. Those of the lactating monkeys had a prolactin concentration about twice as great as that found in the adult females. In most cases, the counts of lactotropes and somatotropes were in agreement with the estimated hormone concentrations. © 1972 by The Endocrine Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe