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Summary1. A study has been made of the effects of a number of drugs which have as a common property the ability to inhibit RNA or protein synthesis, on the development of tolerance to the analgesic effects of morphine, given by intravenous infusion, in rats. 2. Measurements were also made of the effects of the drugs on the incorporation of "4C-lysine into rat brain protein, and "4C-orotic acid into rat brain RNA. 3. Actinomycin D, 6-mercaptopurine and 5-fluorouracil reduced the acquisition of tolerance to morphine at doses which also produced significant inhibition of incorporation of orotic acid into brain RNA. Tolerance development was only affected by 6-mercaptopurine and 5-fluorouracil after intracerebral administration. 4. 6-Mercaptopurine and 5-fluorouracil did not significantly affect the incorporation of lysine into protein, although a small but significant reduction in lysine incorporation was produced by infusion of actinomycin D at 20 ug/kg per hr. 5. Development of tolerance to the analgesic effects of morphine was also reduced by cycloheximide and puromycin. These drugs markedly reduced the incorporation of lysine into brain protein. Puromycin and low doses of cycloheximide (50 ,ug/kg per hr) did not significantly affect RNA synthesis as measured by orotic acid incorporation, but RNA synthesis was clearly reduced by administration of cycloheximide at 200 ,ug/kg per hr.6. These results support the hypothesis that the synthesis of new RNA and protein in the brain is an essential feature of the development of tolerance to morphine in rats.

Endorphin (END) levels in rat pituitary were assessed with the opiate receptor binding assay. Procedures reported to alter hormone secretion from END-rich intermediate or anterior lobes were examined for their effect on END content. Lesions of the paraventricular nucleus (PVN) had no significant effect on END content. Ingestion of 2% NaCl reduced END levels in a significant majority of the animals. Suckling, a natural physiological stimulus, significantly elevated neurointermediate lobe END. Footshock and immobilization each evoked 40–50% reductions in anterior lobe END content. Pituitary ENDs are thus affected by many of the same stimuli that also promote release of a number of peptide hormones derived from the same biosynthetic precursor. However, separate mechanisms likely exist for control of secretion of these peptides from anterior and neurointermediate lobe.

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H UMAN health may depend on the environment and its compartments, which may include climatic factors. These climatic factors and their changes might impact on human health particularly the outbreak of pandemics like COVID-19. The combined stress resulted from climate changes and COVID-19 could be noticed in several countries especially in the developing countries. Malnutrition is considered one of the most important problems in the developing countries in particular under the droughts, flooding, and other climatic events. Malnutrition was aggravated under COVID-19 outbreak in these countries due to the closure of borders between countries, the crisis of global trade, and the global food insecurity. The biofortification process is the sustainable solution to overcome malnutrition, which included very recently using nano-nutrients as called nano-biofortification. The approach of nanobiofortification is a promising tool in producing biofortified edible plants, otherwise this tool still needs more studies to answer the open questions like which nano-nutrients can be used in nano-biofortification? Which recommended doses and crops are considered suitable candidates?