**3.2. Electron microscopy**

Detailed study on electron microscope revealed marked morphological changes of the neuronal dendrites, which were prominent mostly in the secondary and tertiary dendritic branches of a considerable neuronal population of the suprachiasmatic (SCN), supraoptic (SON) and paraventricular nuclei (PVN) of the hypothalamus of patients who suffered from AD. Marked decrease in spine density was noticed in the dendritic branches of the neuronal networks of the hypothalamic nuclei, a phenomenon, which was particularly prominent in the suprachiasmatic nucleus. Small spines and giant spines were also observed in a considerable number of neurons of the suprachiasmatic nucleus. Many large and giant dendritic spines were observed, which included multivesicular bodies.

Mitochondrial pathology was observed in many dendritic profiles in the suprachiasmatic and the paraventricular hypothalamic nuclei, of AD brains. The most frequent findings were the disruption of the cristae and the accumulation either fibrillary or osmiophilic material in the

**Figure 2.** Neuron of SCN of the hypothalamus in a case of AD. The loss of the dendritic branches is obvious. Golgi

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**Figure 1.** Neuron of the SCN nucleus in AD brain. Golgi staining 1200X.

staining, magnification 1200×.

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**Figure 1.** Neuron of the SCN nucleus in AD brain. Golgi staining 1200X.

We estimated also the mean nuclear area, the dendritic profiles of the neurons [72], the spinal density per dendritic segment, the areas of the pre- and postsynaptic terminals [73–75] and

The statistical evaluation of the data was based on the Student t tests. P-values below 0.05

From the anatomical point of view the human hypothalamus is extended from the level of lamina terminalis anteriorly to a level through the posterior commissure and the posterior edge of the mammillary bodies, posteriorly. Using the silver impregnation techniques, including Golgi-Nissl method, we could clearly visualize the neuronal population of the hypothalamic nuclei. We studied all the hypothalamic nuclei extensively; however we focused our description particularly on the suprachiasmatic (SCN), the supraoptic (SON) and the paraventricular

In rapid Golgi method, the morphological and morphometric study of the neurons, demonstrated a considerable decrease of the number of neurons, and a substantial loss of dendritic branches in the patients who suffered from AD (**Figures 1** and **2**), as compared with normal controls (**Figures 3** and **4**). Abbreviation of the dendritic arborization was prominent mostly in the neurons of suprachiasmatic nucleus (SCN) which was associated with marked decrease in the number of dendritic spines (**Figures 5** and **6**), in comparison with the normal control brains (**Figure 7**). The same morphological alterations concerning the dendritic branches and the spines were also observed in the supraoptic (SON) and paraventricular nuclei (PVN) of

The morphometric estimation of the dendritic spines of the neurons of the SCN and SON revealed a dramatic decrease of their number in AD brains in comparison with normal con-

Detailed study on electron microscope revealed marked morphological changes of the neuronal dendrites, which were prominent mostly in the secondary and tertiary dendritic branches of a considerable neuronal population of the suprachiasmatic (SCN), supraoptic (SON) and paraventricular nuclei (PVN) of the hypothalamus of patients who suffered from AD. Marked decrease in spine density was noticed in the dendritic branches of the neuronal networks of the hypothalamic nuclei, a phenomenon, which was particularly prominent in the suprachiasmatic nucleus. Small spines and giant spines were also observed in a considerable number of neurons of the suprachiasmatic nucleus. Many large and giant dendritic spines were observed,

were considered statistically significant, and those bellow 0.01, highly significant.

the number of synaptic vesicles per presynaptic component [54, 75].

**3. Results**

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nuclei (PVN).

trols (**Figure 9**)

**3.2. Electron microscopy**

**3.1. Silver impregnation technique**

the hypothalamus in AD (**Figure 8**).

which included multivesicular bodies.

**Figure 2.** Neuron of SCN of the hypothalamus in a case of AD. The loss of the dendritic branches is obvious. Golgi staining, magnification 1200×.

Mitochondrial pathology was observed in many dendritic profiles in the suprachiasmatic and the paraventricular hypothalamic nuclei, of AD brains. The most frequent findings were the disruption of the cristae and the accumulation either fibrillary or osmiophilic material in the

**Figure 4.** Neuron of the SON of the hypothalamus of a normal brain aged 80 years. The dendritic branches have

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**Figure 5.** Abbreviation of the dendritic arborization is prominent in the neurons of suprachiasmatic nucleus (SCN) which is associated with marked decrease in the number of dendritic spines. Golgi staining, magnification 1200×.

numerous spines. Golgi staining, magnification 1200×.

**Figure 3.** Neuron of the SCN of the hypothalamus of a normal brain aged 75 years.

mitochondria (**Figure 8**). The polymorphism of the mitochondria was also impressive, some of them being giant and very elongated and some being small and round.

The morphometric estimation of the mitochondria in the soma, the dendrites and the dendritic spines of a substantial number of neurons of the suprachiasmatic nucleus in AD brains The Hypothalamus in Alzheimer's Disease: A Golgi and Electron and Microscope Study http://dx.doi.org/10.5772/intechopen.75887 175

**Figure 4.** Neuron of the SON of the hypothalamus of a normal brain aged 80 years. The dendritic branches have numerous spines. Golgi staining, magnification 1200×.

**Figure 5.** Abbreviation of the dendritic arborization is prominent in the neurons of suprachiasmatic nucleus (SCN) which is associated with marked decrease in the number of dendritic spines. Golgi staining, magnification 1200×.

mitochondria (**Figure 8**). The polymorphism of the mitochondria was also impressive, some

The morphometric estimation of the mitochondria in the soma, the dendrites and the dendritic spines of a substantial number of neurons of the suprachiasmatic nucleus in AD brains

of them being giant and very elongated and some being small and round.

**Figure 3.** Neuron of the SCN of the hypothalamus of a normal brain aged 75 years.

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**Figure 8.** Mitochondrial alterations of a dendritic profile of a neuron of SCN of the hypothalamus of a case of AD. Electron

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**Figure 9.** Average dendritic spines per dendritic arbor in SCN and SO neurons, based on measurements of 100 neurons (p < 0.005). AD: Alzheimer's disease, NC: normal control, SCN: suprachiasmatic nucleus, SO: supraoptic nucleus.

**Figure 10.** Mean diameter (in nm) of mitochondria in neurons of suprachiasmatic nucleus, based on estimation of 500

mitochondria (p < 0.05). AD, Alzheimer's disease; NC, normal control.

micrograph, magnification 124,000×.

**Figure 6.** Neuron of the SCN of the hypothalamus of a case of AD. The abbreviation of the dendritic arborization and the poverty of dendritic spines is obvious. Golgi-Nissl staining, magnification 1200×.

**Figure 7.** Neuron of the SCN of the hypothalamus of a normal brain 80 years. The dendritic branches are covered by spines. Golgi staining, magnification 1200×.

revealed that they have an average diameter of 440 ± 250 nm and a mean axial ratio of 1.7 ± 0.2. (**Figure 10**). In the same area the ellipsoid mitochondria of the dendritic spines of normal control brains have an average diameter of 650 ± 250 nm and a mean axial ratio of 1.9 ± 0.2., though the round mitochondria have a mean diameter of 350 nm. The mitochondrial cristae in The Hypothalamus in Alzheimer's Disease: A Golgi and Electron and Microscope Study http://dx.doi.org/10.5772/intechopen.75887 177

**Figure 8.** Mitochondrial alterations of a dendritic profile of a neuron of SCN of the hypothalamus of a case of AD. Electron micrograph, magnification 124,000×.

**Figure 6.** Neuron of the SCN of the hypothalamus of a case of AD. The abbreviation of the dendritic arborization and the

**Figure 7.** Neuron of the SCN of the hypothalamus of a normal brain 80 years. The dendritic branches are covered by

revealed that they have an average diameter of 440 ± 250 nm and a mean axial ratio of 1.7 ± 0.2. (**Figure 10**). In the same area the ellipsoid mitochondria of the dendritic spines of normal control brains have an average diameter of 650 ± 250 nm and a mean axial ratio of 1.9 ± 0.2., though the round mitochondria have a mean diameter of 350 nm. The mitochondrial cristae in

poverty of dendritic spines is obvious. Golgi-Nissl staining, magnification 1200×.

spines. Golgi staining, magnification 1200×.

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**Figure 9.** Average dendritic spines per dendritic arbor in SCN and SO neurons, based on measurements of 100 neurons (p < 0.005). AD: Alzheimer's disease, NC: normal control, SCN: suprachiasmatic nucleus, SO: supraoptic nucleus.

**Figure 10.** Mean diameter (in nm) of mitochondria in neurons of suprachiasmatic nucleus, based on estimation of 500 mitochondria (p < 0.05). AD, Alzheimer's disease; NC, normal control.

AD brains demonstrated serious changes such as disorientation, fragmentation and globular deformation. Mitochondrial alteration was also a frequent phenomenon in numerous astrocytes and pericytes in AD brains.

**4. Discussion**

Hypothalamus is a crucial brain region for the regulation of substantial homeostatic functions, including the circadian rhythms and the sleep–wake cycle. In Alzheimer's disease and other neurodegenerative disorders [76–78] several hypothalamic nuclei are affected. It seems that the hypothalamic nuclei are not involved simultaneously at the early stages of AD. The suprachiasmatic nucleus seems to be more seriously affected than the others in aging [76]. In previous studies, it was clearly revealed that the total cell population in the suprachiasmatic nucleus is substantially decreased in aging and dramatically in AD [78] in which the hypotha-

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The hypothalamic nuclei seem to be involved with various severities in the neurodegenerative process, which progressively results in AD. In addition, the correlation of the alterations of the neuronal dendrites in the hypothalamic nuclei with those seen in the neocortex and the cerebellum, results in concluding that the hypothalamic alterations are modest in comparison with those, which are established in the acoustic area of the cortex, the visual cortex, the pre-

The fact that the hypothalamus is the essential subcortical center of the homeostatic and autonomic processes, may explain the reason why some nuclei such as the supraoptic and the periventricular ones reserve substantial synaptic density, even in the advanced stages of AD,

However, the suprachiasmatic nucleus demonstrated more severe dendritic alterations and synaptic loss than the supraoptic and paraventricular nuclei, a fact which might explain the phenomenon of desynchronization of circadian rhythms in the majority of the patients, who suffer from AD [84] or cognitive decline [85] in the spectrum of other degenerative conditions of the brain [86], given that suprachiasmatic nucleus is of crucial importance for the generation and synchronization of circadian rhythms in man [86, 87]. It is reported that changes of the circadian rhythm (CR), arterial blood pressure and circadian temperature may occur in AD patients [88], especially during the night time [89–91]. Changes also of the melatonin levels are not an unusual phenomenon in advanced senility and AD [92–94]. Sundown syndrome on the other hand, frequently associated with increased motor activity is a rather common

In a large number of neurons of the hypothalamic nuclei mitochondrial alterations were seen mostly in the soma and the dendrites. Mitochondria play an essential role in the energy supply of the cell, which is crucial in the alteration of reduction-oxidation potential of the cell, in the formation of free radicals, in scavenging activity, as well as in the intracellular calcium control and the activation of apoptotic cascade [96–98]. Normally the mitochondria are numerous in the dendritic profiles and the axons, which have a continuous increased activity during the neuronal interactions. Mitochondrial density is also substantially high in the synaptic components, since mitochondria are the main energy generators for the ceaseless

Mitochondrial dysfunction may play an important role for enhancing the neurotoxicity of the Aβ peptide, though increased mitochondrial proteostasis may reduce amyloid-β

lamic dysfunction is closely related to sleep disturbances [79].

in correlation with other subcortical and neocortical neurons,.

frontal areas and the cerebellar cortex [80–83].

condition in advanced AD cases [95].

activity of the synapses.

In a substantial number of neurons of the suprachiasmatic and paraventricular nuclei of the hypothalamus the Golgi apparatus appeared to be fragmented and atrophic (**Figure 11**). It was noticed that the atrophy or the fragmentation of Golgi apparatus (**Figure 12**) and the mitochondrial alterations coexisted with dendritic and spinal pathology in the majority of neurons.

**Figure 11.** Alteration of Golgi apparatus of a neuron of the SCN nucleus of the hypothalamus of a case of AD. Electron micrograph, magnification 124,000×.

**Figure 12.** The volume of Golgi apparatus in nm3 . Based on measurements of 100 neurons of SCN (P < 0.005). AD, Alzheimer's disease; NC: normal control, SCN, suprachiasmatic nucleus.
