Abstract
Abstract in English, Malay (macrolanguage) Environmental temperature rises are powerful stimuli that can alter both the sympathetic nervous system and the hypothalamic-pituitary-adrenocortical axis (HPA). Heat stress has been shown to harm pregnancy outcomes such as causing spontaneous abortion, low birth weight, growth retardation and stillbirth. Supplementation of bee bread in pregnant rats under heat stress exposure has been shown to improve the pregnancy outcomes. However, whether supplementation of bee bread during heat stress exposure may also reduce the level of the stress hormone, corticosterone has yet been reported. Therefore, this study aims to determine the effect of bee bread on corticosterone level, progesterone level, oestradiol level and zonation of the adrenal cortex of pregnant rats under heat stress exposure. Pregnant rats were randomly categorised into four groups (n = 6): Control (C: standard feeding), Treatment 1 (T1: 0.5 g bee bread/kg body weight/day), Treatment 2 (T2: standard feeding with heat exposure), and Treatment 3 (T3: 0.5 g bee bread/kg body weight/day with heat exposure). Bee bread (0.5 g/kg body weight/day) was force-fed to pregnant rats through oral gavage beginning on day 0 of pregnancy and continuing until delivery. Heat stress was generated experimentally by putting both T2 and T3 rats in an egg incubator for 45 min daily at a temperature of 43°C till delivery. On a postnatal Day 21, dams were euthanised to assess serum corticosterone, progesterone, oestradiol levels and adrenal gland histology. Rats in the T2 group had a significantly (P < 0.05) increase in the zona fasciculata thickness (94.95 ± 1.55 μm) and higher corticosterone levels (49.57 ± 1.57 ng/mL) compared with control. However, supplementation of bee bread during heat stress was able to show an improvement in adrenal zona fasciculata thickness by decreasing to 79.89 ± 3.08 μm and corticosterone level reduced to 35.31 ± 1.73 ng/mL significantly (P < 0.05). Therefore, these findings may imply that bee bread is effective as a neutralizer in lowering the production of stress hormone. Peningkatan suhu persekitaran adalah rangsangan kuat yang boleh mengubah kedua-dua sistem saraf simpatetik dan paksi hipotalamus-pituitari-adrenokortikal (HPA). Tekanan haba telah terbukti membahayakan hasil kehamilan seperti pengguguran spontan, berat lahir rendah, terencat pertumbuhan dan kelahiran mati. Suplemen roti lebah pada tikus hamil di bawah pendedahan tekanan haba telah menunjukkan pemulihan dalam hasil kehamilan. Walau bagaimanapun, sama ada suplemen roti lebah semasa pendedahan tekanan haba juga boleh mengurangkan tahap hormon tekanan, kortikosteron masih belum dilaporkan. Oleh itu kajian ini bertujuan untuk menentukan kesan roti lebah terhadap paras kortikosteron, paras progesteron, paras estradiol dan pengezonan korteks adrenal tikus hamil di bawah pendedahan tekanan haba. Tikus hamil secara rawak dikategorikan kepada empat kumpulan (n = 6): Kawalan (C: pemakanan standard), Rawatan 1 (T1: 0.5 g roti lebah/kg berat badan/hari), Rawatan 2 (T2: pemakanan standard dengan pendedahan haba), dan Rawatan 3 (T3: 0.5 g roti lebah/kg berat badan/hari dengan pendedahan haba). Roti lebah (0.5 g/kg berat badan/hari) telah diberi makan secara paksa kepada tikus hamil melalui gavaj oral bermula pada hari 0 kehamilan dan berterusan sehingga bersalin. Tekanan haba dijana secara eksperimen dengan memasukkan kedua-dua tikus T2 dan T3 ke dalam inkubator telur selama 45 minit setiap hari pada suhu 43°C sehingga kelahiran. Pada hari ke-21 selepas kelahiran, ibu tikus telah dikorbankan untuk menilai paras kortikosteron, progesteron, estradiol dan histologi kelenjar adrenal. Tikus dalam kumpulan T2 mempunyai peningkatan ketara (P < 0.05) dalam ketebalan zona fasciculata (94.95 ± 1.55 μm) dan tahap kortikosteron yang lebih tinggi (49.57 ± 1.57 ng/mL) berbanding dengan kawalan. Walau bagaimanapun, suplemen roti lebah semasa tekanan haba telah menunjukan kesan positif dengan pengurangan ketebalan zona fasciculata (79.89 ± 3.08 μm) dan hormon kortikosteron (35.31 ± 1.73 ng/mL) secara ketara (P < 0.05). Oleh itu, penemuan ini mungkin membayangkan bahawa roti lebah berkesan sebagai peneutral dalam menurunkan pengeluaran hormon tekanan.