Adeghate E, Ponery A S, Pallot D J, Singh J
Department of Human Anatomy, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al Ain.
Tissue Cell. 2000 Jun;32(3):266-74. doi: 10.1054/tice.2000.0107.
The distribution of adrenergic, cholinergic and amino acid neurotransmitters and/or their enzymes were examined in both the normal and diabetic pancreatic tissues in rat using immunohistochemistry to determine whether changes in the pattern of distribution of nerves containing these neurotransmitters will occur as a result of diabetes mellitus. In addition to this, the effect of noradrenaline (NA), adrenaline (ADR), acetylcholine (ACh) and gamma-amino butyric acid (GABA) on glucagon secretion from the isolated normal and diabetic pancreatic tissues was also investigated. Pancreatic fragments from the tail end of normal and diabetic rats were removed and incubated with different concentrations (10(-8)-10(-4) M) of these neurotransmitters. Glucagon secretion into the supernatant was later determined by radioimmunoassay. NA at 10(-6) M evoked a three-fold increase in glucagon secretion from normal pancreatic tissue fragments. In diabetic pancreatic tissue, NA at 10(-6) M was able to increase glucagon secretion 1.5 times the value obtained from diabetic basal. ADR (10(-8) M) increased glucagon secretion slightly but not significantly in normal pancreatic tissue. ADR inhibited glucagon secretion from diabetic pancreas at all concentrations. ACh (10(-8) M) induced a five-fold increase in glucagon secretion from normal pancreatic tissue. In a similar way, ACh evoked a two-fold increase in glucagon secretion from diabetic pancreas at 10(-4) M. In normal pancreatic tissue, GABA produced a slight but not significant increase in glucagon secretion at 10(-4) M. In contrast to this it inhibited glucagon secretion from diabetic pancreatic tissue fragments at all concentrations. In summary, tyrosine hydroxylase- and choline acetyltransferase-positive nerves are equally well distributed in both normal and diabetic rat pancreas. There was an increase in the number of glucagon positive cells and a decrease in the number of GABA-positive cells in diabetic pancreas. NA and ACh have a potent stimulatory effect on glucagon secretion from normal pancreatic tissue fragments, whereas ADR and GABA produced a small but not significant increase in glucagon secretion from normal pancreas. NA and GABA stimulated glucagon secretion from diabetic pancreas. In contrast, ADR and ACh inhibited glucagon secretion from diabetic pancreas. Neurotransmitters vary in their ability to provoke glucagon secretion from either normal or diabetic pancreas.
利用免疫组织化学方法，检测正常和糖尿病大鼠胰腺组织中肾上腺素能、胆碱能和氨基酸神经递质及/或其酶的分布，以确定糖尿病是否会导致含有这些神经递质的神经分布模式发生变化。除此之外，还研究了去甲肾上腺素（NA）、肾上腺素（ADR）、乙酰胆碱（ACh）和γ-氨基丁酸（GABA）对分离的正常和糖尿病胰腺组织胰高血糖素分泌的影响。从正常和糖尿病大鼠的尾端取出胰腺片段，与不同浓度（10^(-8)-10^(-4) M）的这些神经递质一起孵育。随后通过放射免疫测定法测定上清液中胰高血糖素的分泌量。10^(-6) M的NA可使正常胰腺组织片段的胰高血糖素分泌增加三倍。在糖尿病胰腺组织中，10^(-6) M的NA能够使胰高血糖素分泌增加至糖尿病基础值的1.5倍。10^(-8) M的ADR在正常胰腺组织中使胰高血糖素分泌略有增加，但不显著。ADR在所有浓度下均抑制糖尿病胰腺的胰高血糖素分泌。10^(-8) M的ACh使正常胰腺组织的胰高血糖素分泌增加五倍。同样，10^(-4) M的ACh使糖尿病胰腺的胰高血糖素分泌增加两倍。在正常胰腺组织中，10^(-4) M的GABA使胰高血糖素分泌略有增加，但不显著。与此相反，它在所有浓度下均抑制糖尿病胰腺组织片段的胰高血糖素分泌。总之，酪氨酸羟化酶和胆碱乙酰转移酶阳性神经在正常和糖尿病大鼠胰腺中的分布相同。糖尿病胰腺中胰高血糖素阳性细胞数量增加，GABA阳性细胞数量减少。NA和ACh对正常胰腺组织片段的胰高血糖素分泌有强烈的刺激作用，而ADR和GABA在正常胰腺中使胰高血糖素分泌有少量增加，但不显著。NA和GABA刺激糖尿病胰腺的胰高血糖素分泌。相反，ADR和ACh抑制糖尿病胰腺的胰高血糖素分泌。神经递质从正常或糖尿病胰腺中激发胰高血糖素分泌的能力各不相同。
