[The prolactin level in the cerebrospinal fluid and blood plasma of cattle at different stages of ontogeny].

The prolactine level in the CSF was shown to be higher than in the blood plasma in 5-8-month-old and 1-2-month-old calf. On the 9th month, the prolactine level in the blood becomes higher than in the CSF. No sexual difference was found in the prolactine levels.

[Lactogenic receptors on cow granulosa cells].

Bovine prolactin (BPRL) binding to cow granulosa cells depending on the antral follicular diameter has been studied. The data obtained point to the existence of one type of low affinity PRL-binding sites on granulosa cells. No reliable differences in the parameters of BPRL interaction with lactogenic receptors in the dynamics of folliculogenesis have been found.

[Hydrolysis of prolactin by a serine proteinase from mammary gland secretory cell mitochondria].

Mitochondrial proteinase isolated from secretory cells of the mammary gland of lactating rats able to hydrolyze 125I-labeled and native prolactin (PRL) has been studied. The enzyme represents a serine proteinase and is localized in the inner mitochondrial membrane. The molecular mass of the enzyme is 17-18 kDa, pH optimum is at 8.

[Two types of prolactin-binding sites on membranes of cow milk fat globules].

Prolactin (PRL) binding to specific receptors of cow milk fat globular membranes (MFGM) has been studied. The data obtained point to the existence of two PRL-binding sites on cow MFGM. The parameters of PRL binding to lactogenic receptors have been estimated for a two-binding-site model.

[Prolactin levels in the blood of ruminants].

The contents of prolactin in the blood of male ruminants and dry-period, pregnant, and lactating female ruminants was studied by a radioimmunological method. The prolactin was found to take part not only in the lactation processes but in some other functions too. The utmost changes of the prolactin contents were observed during milking: the release of prolactin from the adenohypophysis is the unconditioned reflex action.