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Biomedical subjects

V Strbák

Publications and source records attributed to V Strbák.

89 records · Page 5Linked to original sources
PubMed1975

Response of the adrenals to stress in animals from litters with different numbers of young.

Undernutrition and overnutrition during the suckling period -- achieved by adjusting the number of infant rats per litter to 4, 8 and 14 -- resulted in a decrease in the plasma corticosterone level and in corticosterone production by the adrenals in vitro in overfed animals at the age of 30, 180 and 300--360 days. An enhanced response to ether anaesthesia or immobilization stress was found in overfed animals from the smallest litters. The results show that a change in postnatal nutrition and in social relationships in the litter influences maturation of the hypoathalamo-hypophysio-adrenal regulatory system; in adulthood this is manifested in changes in production of the adrenal hormones and in the reaction of the adrenals to stress.

Adrenal Glands↗
PubMedDate not supplied

Thyrotropin-releasing hormone in rat heart: effect of swelling, angiotensin II and renin gene.

AIM: This study was performed to examine thyrotropin-releasing hormone (TRH) secretion and regulation in rat heart. METHODS: Expression of prepro-TRH gene in left atrium and left ventricle was studied by RT-PCR. TRH secretion from slices of left auricle and left ventricle in response to cell swelling (induced by hypotonic medium or ethanol in isosmotic medium), angiotensin II and losartan and their combinations was studied. RESULTS: RT-PCR revealed two times higher prepro-TRH expression in left auricle than left ventricle. In transgenic rats with extra copy of mouse renin gene a marked increase of prepro-TRH expression in the heart was noted but the relative difference between left atrium and left ventricle persisted. The swelling stimulated TRH release from both left auricle and left ventricle and this stimulation could not be inhibited by bumetanide. Angiotensin II (10 nmol L-1) added into medium significantly decreased basal secretion of TRH. The inhibiting effect of Angiotensin II was prevented by 1 micromol L-1 losartan, an angiotensin II AT1 receptor blocker. When angiotensin II and hypotonicity were applied simultaneously, swelling-induced secretion persisted. CONCLUSION: TRH secretion from heart slices has attributes of regulated secretion--depending on the stimulus it could be either stimulated or inhibited. Renin positively affects prepro-TRH expression in the heart. Angiotensin II inhibits TRH secretion from heart tissue by a mechanism involving AT1 receptors. Swelling-induced TRH secretion overrides inhibitory effect of angiotensin II. Swelling could be a useful tool when natural or pharmacological secretagogue is unknown. Peptides and proteins released by swelling could be mediators of local and remote ischaemic preconditioning protecting from subsequent ischaemia.

Angiotensin II↗
PubMedDate not supplied

Hormones and bioactive substances in milk: a rudiment or a message?

The composition of milk is the result of an evolutionary process with both positive and negative natural selection mechanisms where variants with components supporting offspring development from birth to reproduction (but not later) are preferred. Almost all known hormones and many other bioactive substances are present in milk of various species. Some of them are synthesized by the mammary gland, the others are passively or selectively transported (and eventually modified) from blood into milk. Hormones in milk are of importance for the regulation of the functions of the mammary gland itself. There are indications that they affect (sometimes permanently) both functions of suckling GIT and other functions after their resorption during the defined developmental periods. The definite role of these messages for further offspring development remains to be established.

Animals↗
PubMedDate not supplied

TRH analogs with 4-nitro- and 4-N-butyloxycarbonylamino-1-methyl-2-pyrolylcarboxylic acid in position 1. Synthesis and biological properties.

Two new analogs of thyrotropin-releasing hormone (TRH), obtained by the replacement of the L-pyroglutamic acid residue with 4-nitro- or 4-N-butyloxycarbonylamino-1-methyl-2-pyrolylcarboxylic acid (analogs 1, 3), and three related derivatives, in which also the L-histidine residue was replaced with L-norvaline (analogs 2, 4) or L-norleucine (analog 5), were synthesized and tested for endocrine and central nervous system (CNS) activity. The replacement of the L-pyroglutamic acid residue with 4-nitro-1-methyl-2-pyrolylcarboxylic acid (analogs 1 and 2) resulted in the separation of the endocrine from the direct CNS activity. The effect of these analogs on the sleeping time, rectal temperature and breathing frequency, was either the same or greater than that of TRH. However, neither the correlation between the binding of analogs to TRH receptors in the brain nor their activity on the CNS parameters measured was found. Analogs 3, 4 and 5, containing 4-N-butyloxycarbonylamino-1-methyl-2-pyrolylcarboxylic acid in place of L-pyroglutamic acid, were inactive.

Animals↗